Be careful when using Instant Message application


These days smartphone has come into wide use in the world. Naturally, they are not only conducting a lot of business on their smartphone but also are able to use the internet anytime anywhere on their smartphone. Although the people are more convenient than in the past by using the smartphone, their personal information is more dangerous than in the past. In some country, instant message application is more popular than traditional text message because the smartphone distribute widely in the world.

Advantage of Instant Message

Instant message application gives many advantages to the users.

  • The users of instant message application can send and receive instant message in real time.
  • While the communication between the users of instant message application, the users can share the files such as pictures, voice message, video and etc.
  • Although the users do not sign up for the telecommunication company, they can send and receive instant message anywhere if they can use wireless internet on their smartphone.
  • The instant message allows real-time group chatting.

Disadvantage of Instant Message

  • There is a security issue.

The hackers can attack the users’ smartphone by sending some files, such as virus, trojan horse and etc., to general users.

There is another shocking example about the security issue of instant message. Last month, there is an issue about the instant message application, Kakaotalk in South Korea. Surprisingly, Korea government and prosecutors eavesdropped and monitored from conversation content of criminals to conversation content of innocent people through instant message application server. This means that Korea government and prosecutors can get access to online conversation through server. Of course, some Koreans are worrying about online privacy. More than two million Korean users of the Kakaotalk move to secure instant message application. After the issue, Kakaotalk CEO said that we will create message security system during conversation between the users until the end of year and will shorten the store time about the conversation contents in server.

However, fortunately, there is an alternative method to avoid the security issue when the users use the instant message. The mass media introduces an alternative application, ‘Telegram’, instead of Kakaotalk due to following reasons.

  • The user sends encrypted messages. When the user receive encrypted message, they  decrypt received message to check the message.
  • The South Korea users can avoid surveillance from government and prosecutors because Telegram application servers are not in South Korea.
  • All faculties including Telegram CEO cannot see the messages of the users because instant messages between the users do not save in the server.

I am using the instant message application on my smartphone because it is more convenient than traditional text message. Although instant message makes the users more convenient, they should be careful what they use the instant message. When I write the message on instant message application, I take care my personal information as well.

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Do you know about 3D printer?


3D printer is defined by one word ‘Innovation.’ This is a huge innovation for any industrial categories.
Now, many countries has invested 3D printing indurstry. Do you know how much it is? Well, prices are vary between starting price at $1300 up to $36,000. This printer price is really expensive.

What is 3D printer?

3D printer refers to any of the various processes for printing a three-dimensional object. Primarily additive processes are used, in which successive layers of material are laid down under computer control.These objects can be of almost any shape or geometry, and are produced from a 3D model or other electronic data source. A 3D printer is a type of industrial robot(Wiki pedia). Some people really want to make prototype quickly when they start to produce something. Idea of 3D print  is from this concept that people want to see right away. This picture is from 3D printer.

This is a kind of robot machanism for three dimentional printing. Let me introduce its advantages.

  • Time saving:Before inventing 3d printer, Engineer made prototypes with photopolymers(material), and changed their shapes using cutting machine that photopolymers transfer to plastic material. This process was taking about 6 to 8 weeks. But now, we can print out with CAD file through a 3D printer, and make prototype right away as perfect shape. .
  • Reduce production cost: Most manufactor factory depends on cheap labor.  Most factories are located in developed country. But, as 3D printer goes to developed well, we don’t have to depend on labor cost in near future. Without labor cost, we can construct factory in everywhere. That means that we can save production cost to shorten process of distribution.

Howerver, these advanatages come with disadvantages too.

  • Cheap cost worker will lost their job: If 3D printer works properly in basic manufactoring process, no more needs human labor. 3D printer will take over their simple labor job.
  • Economical and Political unrest effect: Too many manufacturing process can be skipped because of 3D printer. It will make  huge problems on economical and political areas.

I just brifely explained about 3D printer. It has a lot of advantages as I mentioned above. That is why many countries and company research to improve 3D printers. But, we have to approach more carefully because 3D printer has not only benefit, but also a lot of risk toward our life. Does anyone have good idea to adjust these advantages and disadvantage

Here is youtube video!




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Introduce new Android 5.0 Lollipop here!


You may concern what O/S system is better for your future cell phone. I am going to show new Android opertation system. Name is Android 5.0 Lollipop..! We have to know how to use for my cellphone O/S. Sometime we don’t know exactly what function is available for my cellphone. Actually, most cellphone box doesn’t have manual properly. Just it is written like ‘go to the website.’ Surely, every devices has different look, layout, or design. But, important fact is that operations of cellphone are very very similar likely same to use it. If you know about new Andoid system well, you can practical use new fuctions. This is a new update for 2 years. Yes, people has been waiting during 2 years! What do you think that new version is going to flow which direction?

Big Change of Design

Big change is that new Android 5.0 has been changed their look. It is more designerble and simple design.Especially, they have added animation when user move to other section. Its looking is more simple than previous version. Google have added more animation function when user move to the ohter screen. This is only I concern to affect with system speed when I heard . But they also upgrade their system bits as 64 bits. We don’t have to worry about this thing.

New function

  • Hide basic application:  They have added new functions. New function is that user can hide basic applications. Sometimes, we are tired about basic application such as Tmobile shop, samsung store and so on. It was very annoying, but now we can hide these kind of basic application finally.
  • More longer battery life: User’s most unsatisfied thing was short battery life, even user doesn’t use anything like standing times android battery goes down, but now they have improved this bad thing! more longer battery life!
  • Multiple user: Sometimes, Friends or family want to use my phone, but we have personal information inside! Now, on Android 5.0 has multiple log in function. Each person can log in their account.Nobody look up your personal stuff!

64bits Memory

This is a first version of 64bit memory using. Probably, some people doesn’t understand about 64bits meomory stuff. As shortyly briefing, We can use over 4GB memory on 64-bits memory system. That means that system will be more faster and more memory spaces when we run heavy program or multi-tasking in same time. but unfortunately, Android market doesn’t have heavy program so far. As time goes by, I expect to get more benefits after developing application program.


Does anyone have any ideas to know more about Android 5.0? Hopefully, you guys get informations from this technical commucation.Also I attached more site links. you guys can get more detail things.

Here is video, it will explain how its look.

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Pros and Cons of VoLTE



Last month, Verizon wireless released VoLTE, Voice over LTE. Generally, when we try to call on a smartphone, the smartphone changes 4G to 3G. This indicates the smartphone call using 3G, not 4G or LTE. However, VoLTE means that the smartphone use LTE when calling.

The Advantage of VoLTE

The Verizon wireless customers have advantages if they use VoLTE.

  1. The customers can use high quality voice call and high quality video call.
  2. The customers can connect their calls much faster than service provider using traditional GSM technology (e.g. T-Mobile) or CDMA technology (e.g. Verizon).

Let’s watch the video about Verizon VoLTE demo.

Like the picture and video, the VoLTE users can use HD video call and HD voice call as I wrote above. I think this is really amazing technology in the telecommunication industry.

The Disadvantage of VoLTE

However, there are disadvantages in order to use VoLTE.

  1. A smartphone which you are using may not support VoLTE because the bandwidth between LTE and VoLTE is different. Thus, the customers have to change your smartphone to the smartphone that supports VoLTE.
  2. Although you have the smartphone that supports VoLTE, you may not use VoLTE because callee’s phone doesn’t support VoLTE. In other words, both callee and caller need to use a VoLTE-enabled phone.
  3. One more thing!  VoLTE-enabled smartphone is more expensive that LTE smartphone.

Therefore, when we buy the smartphone, we should think whether VoLTE really need for us or not.

My Opinion

In my opinion, the LTE smartphone is enough to use. We can hear callee’s voice well when the users are talking on the phone. Thus, I will keep using my smartphone because it is working very well. However, if I should change my smartphone, I will consider VoLTE smartphone.  I personally believe that development of telecommunication technology will yield better improvement of telecommunication technology in the future. Although there are technologies that do not need for us right now, the technologies will make us convenient in the future.

My professor who works in telecommunication industry said that other carriers, such as T-Mobile, Sprint, AT&T and etc., have plan to start VoLTE until the end of year.

Do you think that you need VoLTE when using the smartphone?

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Developer Resigns After Threat


Recently, a video game director named Michael Maulbeck resigned from his company, Code Avarice. A video game they were working on called Paranautical Activity was removed from the Steam video game service right after its release. Supposedly, Valve, the company that runs Steam, removed their game after Michael tweeted out saying that he was going to kill Gabe Newell, the head of Valve. Valve went on to state that they have zero tolerance for that kind of behavior. Michael stated that he left the company because he felt that he should take the blame for what occurred and believes Valve should harbor no ill will towards the others that worked on the game.

This article relates back to our discussion about social media management and how people carry themselves on the internet. Obviously, there were big consequences to what the developer did. In my opinion, the entire team that worked on the game should not have been punished for what happened. It was right for Michael to have resigned and hopefully Valve will change their mind about keeping the game off Steam. Even so, the damage has been done and the game’s sales have probably suffered because of this. It just goes to show that one should be careful about what you post online, especially something as public as this.

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Proposal for Optional Linux OS on Campus Computers


In a school with such heavy focus on Engineering and Computer Science, it makes sense to offer a linux based operating system as an option on select computers. A linux based system would offer a couple pros over our current computer lab setup.


  • Linux utilities

    The default GNU/Linux environment offers a wealth of commandline utilities. Any of the shells available to linux are also ideal for scripting and handling plain text.

  • Development environment

    Most major IDEs on windows are also available on linux, perhaps with even more integration. Most of the dependencies (gcc, make, ..) of these software are already native to linux. Even without IDEs, a linux based OS is already an excellent development environment. Extensible editors like Vim and Emacs both run natively in linux.

    These editors are available to Windows as well, however, linux’s text manipulation utilities makes these editors even more powerful.

  • Content authoring tools

    Traditional word processing software like Libreoffice exist. There is even the option to use cloud based solutions like Google Docs. These should meet the needs of most students. On the flip side, linux offers a plethora of texlive and markdown tools to render beautiful documents.

  • Software Repositories

    Many of the most used software in linux are packaged and hosted in the official repositories of the linux vendor. This means that all software will be downloaded from the same source, and all software will be kept up-to-date using only the system’s package manager.

    There is also the added benefit of using software that has gone through quality assurance within the linux distribution.

  • Free

    Linux distributions are normally free to use. All the software in the repositories are free as well.


  • Limited access to proprietary software

    Some proprietary software, such as those from Microsoft will not run natively on Linux. These programs might run under compatibility layers such as WINE, but the solution is less than ideal. Another software company that does not provide linux software is Adobe. They have authored many crucial programs such as Photoshop that do not run natively in linux.

Why Linux?

In addition to the listed pros, there are yet more reasons to enable the use of linux in the school computer labs. * Many cs courses require or recommend linux environment * Vim or Emacs is the preferred editor for many professors * Remote access to an off-site linux server is no longer needed to complete homework

The addition of linux systems in the labs will greatly improve the working conditions of our Computer Science students.

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Unique Instructions to Use an iPhone 6/6 plus Due to Terrible Designs


Apple recently launches the new iPhones, which are iPhone 6 and iPhone 6 plus. Everybody admits that iPhone 6 series is expensive and powerful. However, the terrible designs make it necessary to pay attention to. Here are some unique instructions as the cost of the terrible design.

  1. Suit Up for Your iPhone.

Find a beautiful case for your iPhone. Do you think the new iPhone is beautiful? The cheap plastic strips are so ugly.  The strips are for better signals, but, I want to know why the designers cannot make it more reasonable. So, suit your iPhone up.

  1. Don’t Put It in Your Jeans Pocket.

The new iPhone 6/6 plus is so easy to bend. Many tests have been published on  to show how delicate the new iPhone is. The terrible structure design cannot promise your iPhone 6 well in years. The stretch force of your Jeans Pocket may bend it especially when you sit down. Or maybe, you just broke it when it hit the chair.

  1. Hold It Carefully Like a Glass.

The screen is not strong enough from failing on the ground. We were all expecting the sapphire screen, but it became a dream. iPhone’s competitor, Lumia series phone, has a very powerful screen without worrying about breaking failing from your hand. And the screen can resist key’s scratches. That is masterpiece. What a terrible design of iPhone’s screen!

So, for the cost of the terrible designs of what Apple has done to iPhone 6/6 plus, you should probably following these instructions. Nobody wants to have a garbage just after he paid an expensive price. If it’s still in one piece, iPhone 6/6 plus is still a great phone.

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How tech giants deal with government information requests


The United States’ government’s surveillance is no longer a secret after the NSA Warrantless Surveillance Controversy. It is unfavored by everyone living in USA. But the real wars are between the government and tech industry giants, because tech giants claims to protect users’ privacy. This article summarizes what they do.


Facebook asks users to use real information, and it didn’t give the Drug Enforcement Administration (DEA) any exception. Facebook insisted that the DEA follow Facebook’s terms of service even in investigations, which prevented the private information from leaking to DEA in unusual way.


After Google found out that the NSA had been sniffing  on the connections between their data centers, it hardened the internal security against the surveillance.


Apple uses a different solution. Apple doesn’t keep users’ private information. Instead, all the information is in users’ hand. In order to help users protect their privacy, Apple is trying to provide them with the best anti-surveillance tool.

Even though government’s surveillance is terrifying, those big companies refuse to comprise users’ interest and use technology to protect users. The two sides of the war show both the downside and power of technology.

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Why Should Windows NT Be a Hybrid Kernel?


There are two main kinds of kernels for commercial operating systems to be, which are Hybrid Kernel and Monolithic Kernel. As the largest commercial operating system, Windows NT choose to be a Hybrid Kernel. But why?

The definitions for these two kinds of kernels are described as:

Hybrid Kernel: A similar kernel to micro kernel. But it includes more codes than micro kernel to increase the performance. Most device drivers and higher level services reside in user mode.
Monolithic Kernel: All operating system services resides in the kernel including all device drivers and file system. It is like a huge file.

From the definition, it shows that Monolithic Kernel is much bigger than Hybrid Kernel but more efficient for running. While Windows NT is a Hybrid Kernel, Linux is a Monolithic Kernel. Then, three possible situations can be the reason for Windows NT to be a Hybrid Kernel.

  • Commercial Operating System Needs to Be Very Stable
  • Commercial Companies Has a Tighter Schedule
  • Save Time for Developers Means Winning

Thus, I am going to expand these reasons for Windows NT to be a Hybrid Kernel but not a Monolithic Kernel.

  • Commercial Operating System Needs to Be Very Stable

For commercial operating system, running stably is the most important feature.

Monolithic Kernel is hard to be coded right without bugs. Hybrid Kernel doesn’t have too many codes so it’s more stable. Thus Monolithic Kernel becomes much more unstable than Hybrid Kernel. Hybrid Kernel is a better choice for Windows NT.

  • Commercial Companies Has a Tighter Schedule

Windows NT, as one of most important products of Microsoft, needs changes frequently. Thus the programmers don’t have plenty of time to change codes. Linux based systems are almost not commercial systems. No schedules for Linux based systems.

Hybrid Kernel is  easier to code right. So the programmers can focus more on the other useful features. Monolithic Kernel needs very long time to code correctly to achieve a certain feature. If programmers need to add a new feature in Monolithic Kernel, they probably need to recode the kernel. Windows NT smartly chooses Hybrid Kernel.

  • Save Time for Developers Means Winning

A commercial company must expand quickly to gain more customers against their competitors. A commercial developer also regard time as money, so they prefer to read light kernels to save time.

Due to the light feature of Hybrid Kernel, it’s faster to read. Monolithic Kernel apparently needs developers to spend more time on it. Windows NT is surely to choose the economic one, Hybrid Kernel.

Thus, Windows NT should choose Hybrid Kernel rather than Monolithic Kernel. It’s the decision of the whole company and it’s a smart one. Choosing a good structure of kernel is a very hard job at first, as almost nobody is willing to change the kernel structure to another which will cost lots of time and money, even customers.

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Which sorting algorithm to choose?


Assuming you are given a bunch of data, how to find an appropriate algorithm for sorting them in some  order? There are many sorting algorithms each with advantages and constraints. If you already know some features of that data, which sorting algorithm you want to choose?

Insertion Sort:

Insertion sort looks at the data one by one in the given order. Each element will be inserted in the array before it so this array is sorted correctly. Insertion sorting takes quadratic time in average case (the data are distributed randomly). It performs very well if the data are nearly sorted and it is very applicable if the data size is small.

Heap Sort:

Heap sort takes the whole bunch of data and apply max-heapify (or min-heapify) multiple times and for the ith time it find the ith maximum (or minimum) element. This sorting algorithm always takes O(nlgn) time whatever the data looks like.

Quick Sort:

Quick sort takes a random element from the data, put all smaller elements in its left side, put all bigger elements in its right side (assuming the data should be sorted from smallest to largest), and applies quick sort on the two separated arrays. This sorting algorithm takes O(nlgn) in average case but it might take quadratic time if you get very bad luck.

Merge Sort:

Merge sort takes the array and break them equally into two until each array has one or two elements. Then it sort each array and merge each two of them until the array is complete. This algorithm takes O(nlgn) time basically  in every case.

Counting Sort:

Counting sort takes the array and count the number of each element. Then it inserts each element into its correct position in the reversed given order according to the number of elements that are less than it. This algorithm performs very well if the range of the data are small and the data have some duplicates. It only takes linear time in suitable cases. But it’s not applicable if the data range are large.

Radix Sort:

Radix sort sorts the numbers based on their last digits, then sort them based on the second last digits, and so on… This algorithm can also take linear time in appropriate cases where  the number of digits of each element is small. But it’s not good to use it if one or more numbers have a lot of digits.

Bucket Sort:

Bucket sort looks at the most significant digit of each number and put it into the corresponding bucket labeled with that digit. And it applies insertion sort for elements in each bucket. This algorithm must take numbers whose most significant digits are in same digit place (or it could take an array of strings and sort them alphabetically). In this case, the algorithm takes linear time to run.

Bubble Sort:

Bubble sort looks up the whole array and put the maximum number at the top, shift all the elements previously before it 1 element back, and repeat. This sort only performs well if the data are nearly sorted. In other cases it takes quadratic time and is much slower than insertion sort.

Selection Sort:

Selection sort looks up the whole array, switch the maximum number with the first number, and repeat. This algorithm is really easy to implement but it performs bad in every case. It takes quadratic time to run and is much slower than insertion sort.

There are still more sorting algorithms to choose. And all of them have their advantages and disadvantages. Even selection sort has a good side since it takes only a little memory to run. Choosing algorithm should depend on the features of the data, like the data size, range, and so on.

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