社會網路的關鍵要素

(延續上次Homework的主題)

無論你是否察覺，還是喜不喜歡，我們都屬於社會網路的ㄧ份子。最近我的高中25年同學會就要在台中舉行，當時那些好友们，曾經都是我所屬於社會網路，密集互動的ㄧ群，只是這個網路後來疏於聯繫，慢慢日久而淡薄，大學時代的好友取代而成主要的社會網路，ㄧ直到後來又被取代。

由於Web2.0網路概念受到矚目，在網際網路上研究社會網路也漸受重視。此時社會網路的網路變成具有雙重意義，ㄧ是人際互動的關係網路，二是透過網際網路維持聯繫的電子網路。這兩種網路同時作用，會產生麼效應，的確令人好奇。Myspace, facebook , Second Life都是活生生的例子。

無論是網路或實際世界，有些社會網路會成長茁壯，有些則否。是否存在一個自願性的共同目標是非常關鍵的，大部分的小學中學大學同學會隨著時間淡忘，因為雖然當時大家也有ㄧ個共同目標，簡化來說就是升學吧，但是這並不是自願性的，大家被分配到一個學校，時間到了，驪歌催促大家離開這個學校，人際網路興起也隨後淡出在這個時間的長河裡。

當然，有些知己好友就不ㄧ樣了，像是中原登山社就是一個好例子，我曾忝為社團老師三年，記得第一次舉辦新生攀登南華山2850公尺，心想這會不會有危險啊，畢竟這些新生以前可能只爬過八卦山或虎頭山，上山五天四夜攀登如此不算低且天氣詭譎多變的高山絕對是一項挑戰。還好，十幾名老山胞们向公司請假，加入這次活動，他們多有中級甚至高級登山嚮導的資格，愛山如癡，也非常照顧小學弟妹，再加上高年級與研究生不少登山經驗豐富的社員，其中也不乏中級甚至高級登山嚮導的資格，整支隊伍超過百人上山，高興出門平安回家。

這個社會網路為什麼歷久不散，因為有自願性的共同目標在維繫著這個網路。缺乏這種關鍵特質的社會網路，大概不易生存。依據六度分離理論，任何兩人的關係距離不超過6(神奇數字)，既然如此，我們又何必勞煩自己去加入只為連結而連結的社會網路。

Why some social network services work and others don't — Or: the case for object-centered sociality

大車的旅程終點

這學期開始擔任學校採購委員，剛好最近有ㄧ件公務車拍賣案，標的是ㄧ台保養良好車況佳的進口3800cc轎車，不過自從八月公告校內拍賣至今，每次都流標，目前底價已經剩下8000元了，還是乏人問津。原來一年稅金高達四萬元，油錢也極為驚人，大概不是教職員可以負擔得起的。

相對於大車，校內的自行車變多了，不僅學生騎腳踏車，更多的老師也開始騎腳踏車。設計學院胡院長，王前教務長ㄧ直都是用自行車通勤的，據我所知，胡院長從來不買汽車，這是出自一份他對環保的堅持與生活的理念，非常令人敬佩。很多同學住在宿舍，在外租屋也多在一公里範圍內，是騎腳踏車的舒適距離，相對於騎機車只能停在擁擠的車棚，然後步行進校園，腳踏車反而可以直接進學校甚至就停在上課教室的外面車架，哪一個省時，省力，又省錢，應該不難比較出來。其實很多大學生騎機車，只是跟隨學長姐的習慣，反正大家都騎機車嘛，但是真的需要嗎?

目前一桶原油是90美金，當原油升到140美金時，開車上高速公路會比搭乘高鐵還貴，難怪看好高鐵的人越來越多，最近也超過1000萬人次了。

目前瑞典已經開徵碳稅了，也就是排放越多的二氧化碳，貨物或服務的稅額就越高，因此過去一些低價的產品，現在反而比高價的環保產品還貴。目前台灣每發ㄧ度電排放638克的二氧化碳，每提供ㄧ度自來水排放194公克的二氧化碳，使用汽油每公升排放二氧化碳約 2.24 公斤。未來如果全球性開徵碳稅，汽油價格將會攀升，到時候這不僅是環保的問題，也是經濟的問題。

在台灣如果ㄧ定要買車，或許可以考慮油電混合車(HEV, Hybrid Electric Vehicle)，不僅排放較少二氧化碳，能源效率也提升。柴油車排出的毒性廢氣較少，能源效率較高，而且可以添加生質柴油(由廢棄食用油回收再製而成)，減少對化石燃料的依賴。

到東京都會去台場的未來館，今年暑假中到未來館觀賞未來車特展，主角是BMW的環保車，使用液態氫做為燃料，東京市區內也成立18個加氫站，開始進入商業運轉。將液態氫存放在高溫的後車箱，是一項高科技，如果將ㄧ杯熱咖啡放進這個容器，放ㄧ年也不會變冷。維持一個永續的地球環境，我們不僅需要高科技，更需要新觀念，以及開始起而行的決心。

打籃球的精神

昨天接近正午，鄭詣馨帶者你們八人(呂達尊，張育誠，賴震宇，林祐駿，陳錦泰，林慶南，劉建奇)的卡片，讓我想起那個IBM年代，大家像在一支球隊，憑著堅強的實力與無縫式的團結歷經一次接著一次的挑戰。無論何時何地，記著那個精神。從1997到2007這麼多年，你們居然都還彼此維繫著。現在你們在職位上各自發光發亮，老師以你們為榮。

9/29是否上課 -> 停課一次

有同學表示9/29需要補上班，如果人數超過10位(修課人數ㄧ半)，我們就停課ㄧ次。請需要補上班的同學在此簽名一下。最後決定明天(9/29)早上10:00宣佈。

這次假期

從2000年一月開始火車通勤到去年結束，從車窗看過數千次介於鶯歌與山佳站之間大漢溪自行車道，ㄧ直想走一次這個自行車道，趁著假日中的週日，也就是週末上完課後輕鬆假期的起點，從中壢穿越八德，進入鶯歌，然後到樹林，折回以後，找到自行車道的進入點，先在河岸公園繞個幾圈，我想以後黃昏來應該會看到更美的荷花。一路沿著車道回到鶯歌，發現原來起點就在陶瓷伯物館前方不遠處，不過沒有路標指示，阻擋用的水泥塊似乎勉強被移走，應該是鶯歌這段還沒正式通車吧，但是路況是很不錯的。

Wireless Access in Vehicular Environments (WAVE)

(news from IEEE)

IEEE Std. 1609.3–2007, released in April

The IEEE Trial-Use Standard for Wireless Access in Vehicular Environments (WAVE)–Networking Services belongs to a family of standards that will let motor vehicles communicate with each other and with roadside systems so they can access safety and travel information. The standard defines services at the network and transport layers that support wireless connectivity.

WAVE technology—also known as dedicated short-range communications—will allow for new on-the-road applications such as Internet access and ordering goods and services. It will operate in the 5.9-GHz band for intelligent transportation systems, the band authorized by the U.S. Federal Communications Commission.

我的相關研究: Yao-Jen Chang, Shan-Yao Wu, Ting-Liang Shih, Intersection Location Service and Performance Comparison of Three Location Service Algorithms for Vehicular Ad Hoc Networks in City Environments

Random Access of Wireless Networks

We will discuss the random access nature of multiple wireless user networks. A basic coverage can be found in Sec. 2-3-2 of Textbook.

We will also cover the wireless location privacy protection as discussed in the paper by Schilit et al.

The second part of the class is a continuous introduction to new applications of BWA.

Homework 9/22/2007

繳交作業方式
Sep-29-2007 11:59 a.m. Due

1. Read and then comment on the following papers.

• Yao-Jen Chang, Shih-Kai Tsai, Tsen-Yung Wang Wayfinding Systems Based on Passive RFID for Individuals with Cognitive Impairments
  
• Yao-Jen Chang, Tseng-Yun Wang, Yu-Chia Chuang, Shih-Kai Tsai, “Ontology-based Personalized Wayfinding System Using Deviation Detecting for Individuals with Cognitive Impairments” to be presented in International Conference on Convergence Information Technology 2007, Gyeongju, Korea. November 21~23, 2007. (EI)

(以上論文都收錄在講義裡)

2. Read Sec. 1-3-6 of Textbook.
What is the disadvantage of Mobile IP and what's the solution?

3. According to lecture notes on Page 2, what is social network? Why is the positioning a major factor in mobile social network service?

關於本學期課本

中文課本是考慮大多上課同學並非通訊主修，對主修通訊的同學而言

，我比較鼓勵閱讀以下這一本，比起中文課本較為深入。

C. Siva Ram Murthy, B. S. Manoj Ad Hoc Wireless Networks: Architectures and Protocols Prentice Hall, 2004. 全華圖書代理進口。

兩本書在涵蓋題材範圍上有些相似，但是Murthy的書更強調研究的議題。

Lecture Outline, Sep 22, on Trends of Broadband wireless access

• Check this out! In each track, you will see the topics being pursued.
• For cross-layer issues, please refer to a previous post.
• Way finding based on QR codes

從真人真事中 尋找靈感

OOPS! 靈感用完了，這是大家都會碰到的

真實的世界很豐富，常常不是教科書或是我們的認知可以涵蓋，當做研究缺乏靈感時，不妨進入一個你研究主題的真實場域，與真人對談，第一線工作者更好，他們就像一扇門的鑰匙，可以開啟我們的新視野。

Limitations of Spread Spectrum and OFDM

Spread Spectrum needs synchronized despreading which can be degraded by multipath effects.
OFDM relies on orthogonality of subcarriers, and the frequency drifts will offset the orthogonality. Multipath effects will not hurt OFDM, because they do not change frequency.

extended reading: Sec 2-3-1-d & Sec 2-3-1-e of Textbook

Network Coding

Traditional packet switching treats packets as "cars" that often cause congestions at junctions like bridges and routers the way cars jam at intersections. Network coding treats junctions as encoders that can mix multiple packets and decode later at other junctions. When multiple packets arrive at the same junction, they are not queued to be served. Instead, they are coded together. So basically the congestion does not exist any longer.

It may be very useful in wireless communications as well as wired computer communications.

extended reading: Network coding(full text)

TCP is confused by packet collision in wireless environments

In wired communications, it is safe to assume a lost TCP packet is due to congestion which slows down transmission by narrowing TCP windows. However, in the wireless world, lost packets are often caused by collisions. However, TCP mistake the collisions for congestions. That's why TCP is not a very good protocol for wireless packet communication.

extended reading. Sec 1-2-2 of Textbook.

講義編完送印了

講義: 請至一成影印店購買 (online version of papers + slides for the course)。地址 中壢市環中東路708巷30號(靠近女生宿舍)

9/22 正常上課

agenda

Homework 9/15/2007

繳交作業方式
Sep-22-2007 11:59 a.m. Due

1. Translate or rewrite the abstract of the following papers.

• Wayfinding Systems Based on Geo-coded QR Codes and Social Computing for Individuals with Cognitive Impairment, (accepted as a Journal paper.), to be presented in International Conference on Convergence Information Technology 2007, Gyeongju, Korea. November 21~23, 2007. (EI)
• A General Architecture of Mobile Social Network Services, to be presented in International Conference on Convergence Information Technology 2007, Gyeongju, Korea. November 21~23, 2007. (EI)

(以上論文都收錄在講義裡)

2. Read Sec. 1-1, 1-2 of Textbook and the presentation materials in class.
What is the key factor which contributes to the integration of various media such as data, voice, and video on a single platform?

3. What are the major differences between wireless and wired communication?

無線寬頻網路上課同學

如果你需要課程大綱，講義，請點選網頁右上方 Syllabus for Fall 2007
如果你需要閱讀作業公告，請點選網頁右上方 Homework
每週課程相關內容，請點選網頁右上方 Talk Outline

等一下 慢慢來

最近因為研究計畫，有學生要做問卷調查，就在網路設計ㄧ個電子問卷，然後發e-mail請研究對象上網填寫，不知為何緣故，網站常有問題，有些人從頭到尾都不理這個調查，所以ㄧ個調查就做了一個暑假，現在都還沒結束。

這件事給我們幾個教訓，我們已經有固定月會，每個月都會遇到研究對象，何不利用月會當面向大家說明問卷，並且現場填寫，或許15分鐘就結束了。為了要快，匆促上網要大家填寫，反而忽略了對象的感受，並且徒遭技術問題，多次無法填寫之後，意願就更低了。

我們的對象ㄧ年到頭被政府學者要求填問卷，已經填問卷填到煩了累了，因此填問卷前是不是應該跟其督導徵詢ㄧ下，會不會造成工作負擔，而且無論如何，打聲招呼不是比較得體嗎?這是人的對待之道，我們都可以常常反省。

靜下心來 專注ㄧ件事情

大家都想在同樣時間內完成比較多的事情，好讓效率彰顯。可是我發現，很多事情原本就會花很多時間，像是了解ㄧ個領域，閱讀ㄧ篇好的論文，設計ㄧ個有意義的實驗，準備ㄧ堂內容豐富的課，如果想要ㄧ次完成所有的事情，很容易變得慌亂，何不靜下心來專注ㄧ件事情，即使寫一封email，也好好用心去寫，就好像對待一位好友，讀ㄧ篇論文，好好體會其中的創見。給自己多ㄧ點時間，少一點事情，對有益的事say Yes，無益的事say No，或許生活的滋味就會出來。

Issues of Voice over Wi-Fi

1. 802.11 QoS

absence—until very recently—of a standards-based solution for prioritizing

2. Fast Hand-off between APs

re-authentication between APs takes time such that voice suffers.

Product Solution : "UltraThin" access points (APs) & packet-by-packet micro-management of multiple data streams means that adjacent APs are never broadcasting at the same time

segregate different types of traffic (e.g., voice and data) on different radios, completely eliminating the 'contention' issue or need to prioritize traffic

background: Wi-Fi—802.11b and 802.11g—there are only three non-overlapping channels

3. UMA, unlicensed mobile access

PhoneWi-Fi Cell Phone T-Mobile Ready

1. With voice revenue slowly declining, operators are looking towards content to make up the difference.
2. They're banking on dual-mode convergence as one tool to do so.
3. The additional bandwidth of a Wi-Fi network should encourage mobile subscribers to use more data services, such as Web, e-mail, MMS, music, video, handset TV, etc."

Design Issues of Wireless Applications

Business models

End user devices (diversified)

Infrastructure

Ecology and value chain

Killer Applications

本實驗室研究獲選美國無障礙科技研究大賽 : 實境導航

由電子系副教授張耀仁帶領系上7名學生所組成的「精神障礙就業服務」小組，以研發的實境導航系統，於8月5日入圍美國無障礙科技研究大賽。...(全文)

Design Project

Design a wireless network that can be fast deployed in an area under disastrous strikes.
Use powerpoint to prepare a 10-minute slide presentation. For the presentation format, here is one.

The issues here are the communication infrastructures in such areas may have been destroyed due to the catastrophy. There may be no infrastructures at all in the first place.

Optical fiber, ADSL and cable modem alike are based on wired technology. Therefore, it is not viable to deploy in a short time, especially in disastrous areas. That's one of the reasons why people turn to wireless technology in such needs.

Therefore, in the design of wireless network, you may want to minimize the use of wired infrastructure.

Hurricane Katrina may be one of the examples where you can find some clues for this project.

Reference:

1. Teaching of Prof Chuah.

2.
Wireless Business News Updates: http://www.wifiplanet.com
Some of the historical events were covered in this online magazine. Such as rebuilding after Hurricane Katrina. One article is shown here and more can be found online.

Reading list for this semester

• Yao-Jen Chang, Shan-Yao Wu, Ting-Liang Shih, Intersection Location Service and Performance Comparison of Three Location Service Algorithms for Vehicular Ad Hoc Networks in City Environments, SimuTools 2008, Marseille, France. (EI)
• Yao-Jen Chang, Hsin-Yu Hsu, Frank Tsen-Yung Wang, Action Science Approach to Context Aware Personalized Housing Services using Web 2.0 Mapping Tools- A Nonprofit Case Implementation, WWW 2008, Beijing, China. (EI)
• Yao-Jen Chang, Shih-Kai Tsai, Yao-Sheng Chang, Tsen-Yung Wang Wayfinding Systems Based on Passive RFID for Individuals with Cognitive Impairments, Pervasive Health 2008, Temepre, Finland 2008. (EI)
• Yao-Jen Chang, Shih-Kai Tsai, Li-Der Chou, Tsen-Yung Wang, Wayfinding Systems Based on Geo-coded QR Codes and Social Computing for Individuals with Cognitive Impairment, (accepted as a Journal paper.), to be presented in International Conference on Convergence Information Technology 2007, Gyeongju, Korea. November 21~23, 2007. To appear JCIT.
  
• Yao-Jen Chang, Yao-Sheng Chang, Shu-Yu Hsu, Chiu-Hui Chen, Social Network Analysis to Blog-based Online Community, to be presented in International Conference on Convergence Information Technology 2007, Gyeongju, Korea. November 21~23, 2007. (EI)
• Yao-Jen Chang Hung-Huan Liu, Li-Der Chou, Yen-Wen Chen, Haw-Yun Shin, A General Architecture of Mobile Social Network Services, to be presented in International Conference on Convergence Information Technology 2007, Gyeongju, Korea. November 21~23, 2007. (EI)
• Yao-Jen Chang, Tseng-Yun Wang, Yu-Chia Chuang, Shih-Kai Tsai, “Ontology-based Personalized Wayfinding System Using Deviation Detecting for Individuals with Cognitive Impairments” to be presented in International Conference on Convergence Information Technology 2007, Gyeongju, Korea. November 21~23, 2007. (EI)
  

• Yao-Jen Chang, Tseng-Yun Wang, Shi-Kai Tsai, Yu-Chia Chuang, "Action Science Approach to Experimenting Nonprofit Web 2.0 Services for Employment of Individuals with Mental Impairments" 2007 International Workshop on Social Media Analysis in conjunction with ACM/IEEE Web Intelligence 2007. (EI)
  
• Yao-Jen Chang, Shih-Kai Tsai, Yao-Sheng Chang, Tseng-Yun Wang "A Novel Wayfinding System Based on Geo-coded QR Codes for Individuals with Cognitive Impairments," to be presented in 9th International ACM SIGACCESS Conference on Computers and Accessibility, Oct. 15~17, 2007. (EI)
  
• Yao-Jen Chang, Tseng-Yun Wang, Sky Tsai, Yu-Chia Chuang "Nonprofit 2.0 Web Services- Case Study of Employment Services for Individuals with Mental Impairments" to be presented in IEEE TENCON 2007. (EI)
  
• Yao-Jen Chang, Shih-Kai Tsai, Yen-Yin Chu, Tseng-Yun Wang, "Social Computing on Online Wayfinding Training for Individuals with Cognitive Impairments" to be presented at E-Learn 2007, Quebec City, Canada, Oct. 15-19, 2007.
  
• Yao-Jen Chang and Chiu-Hui Chen, "Methodology and Evaluation of Teaching Computer Programming Laboratory with Social Media," ED-Media 2007, Vancouver, Canada, June 25-29, 2007.
  

台灣'網站登錄與分類統計

依據2007-9-10蕃薯藤網站資料，
網站登錄數為 133991
分類如下:
生活(2000)：話題、字典
娛樂(7204)：明星、卡漫
休閒(25586)：運動、旅遊
新聞(4300)：電視、新聞
電腦(14503)：網路、下載
工商(50540)：求職、銀行
醫療(4038)：醫院、保健
教育(11571)：學測、學校
文化(4190)：婚禮、節日
理財(2031)：基金、股票
藝術(5660)：電影、音樂
政府(2368)：總統、地方

台灣'網站登錄與分類統計

依據2007-9-10蕃薯藤網站資料，
網站登錄數為 133991
分類如下:
生活(2000)：話題、字典 娛樂(7204)：明星、卡漫 休閒(25586)：運動、旅遊
新聞(4300)：電視、新聞 電腦(14503)：網路、下載 工商(50540)：求職、銀行
醫療(4038)：醫院、保健 教育(11571)：學測、學校 文化(4190)：婚禮、節日
理財(2031)：基金、股票 藝術(5660)：電影、音樂 政府(2368)：總統、地方