• 한국정보통신학회논문지
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• 제5권5호
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• pp.941-950
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• 2001

본 논문에서는 3세대 이동통신망이 Mobile IP를 지원하기 위한 통합망 구조를 제시하고, 통 합망에서 DiffServ에 의한 종단간 QoS를 제공할 경우 망을 구성하는 각 요소가 가져야 할 QoS 제어기능 및 메카니즘을 제안한다. 이를 위해 현재 IMT-2000의 QoS 제광 구조를 살펴보고, 통합망의 필요성 및 구조를 제시한 다음, DiffServ 클래스와 무선채널과의 매핑관계 및 종단간 QoS 제공 메카니즘을 제안한다. 또한 CDMA 이동인터넷망에서 QoS지원을 위한 무선접속 링크레벨의 성능을 분석한다. 데이터 트래픽의 경우 SREJ ARQ방식과 Type-1 Hybrid ARQ방식을 비교 분석하고, 음성 트래픽의 경우 BCH 코딩을 사용하여 데이터 트래픽 부하변화에 따른 음성 패킷의 에러율을 분석한다 분석 결과 구현상의 복잡도는 높으나 QoS를 만족시키는 적응적 ARQ와 적응적 FEC 코딩을 이용하는 방식이 보다 효율적임을 알 수 있다.

• 대한전자공학회논문지SD
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• 제38권12호
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• pp.66-74
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• 2001

IMT-2000의 무선접속 기술 요소 중 multirate을 위한 Multi-Code(MC) CDMA 시스템의 이동국 Rake 수신기는 다수의 채널로 전송된 신호들을 동시에 복조해야 하므로 Rake Finger에서 트래픽 채널을 복조하는 데이터 상관기의 수가 왈쉬 코드 채널의 수만큼 증가하게 되어 신호처리의 복잡도가 증가되는 단점을 갖게 된다. 본 논문에서는 데이터 상관기들의 증가로 인한 데이터 처리시간 지연을 감소시키기 위해 Walsh Switch, 공유 accumulator, 그리고 파이프라인 FWHT(Fast Walsh Hadamard Transform) 알고리즘을 적용한 새로운 Rake Finger 구조를 제안했다. 컴퓨터 시뮬레이션 결과 왈쉬 코드 채널의 수 에 대한 데이터 상관기의 연산 동작 수는 512 additions에서 160 additions로 약 3.2배 감소하였고, Rake Finger의 데이터 처리시간은 110,696[ns]에서 90,496[ns]로 18.3% 감소하였음을 확인하였다.

• 대한전자공학회논문지TC
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• 제37권4호
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• pp.9-16
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• 2000

이 논문에서는 코드분할다중접속 시스템에서 다중접속간섭을 제거하는 방법 중 하나인 병렬형 간섭 제거기에(PIC) 초기단 성능 개선을 위해 전단에 순차적 간섭 제거기를(SIC) 사용한 혼합형 간섭 제거기의 구조를 제안하고, 병렬형 간섭 제거기와 순차적 간섭 제거기 그리고 비슷한 구조의 혼합형 간섭 제거기와의 성능을 비교 분석한 것이다. 성능 비교를 위해 채널 환경은 Rayleigh-fading (Jake's model)과 가산성 백색정규잡음환경에서 모의 실험을 하였고, 시스템의 복잡도, 지연시간 그리고 오류율에 대해 비교하였다. 모의 실험을 통하여 제안된 혼합형 간섭 제거기가 순차적 간섭제거기의 오류율에 근접하면서 지연시간을 절반정도 줄였고, 제안한 혼합형 간섭제거기 후단의 병렬형 간섭제거기를 1단을 사용함으로서 복잡도면에서 1단을 사용한 일반 병렬형 간섭제거기에 비해 1/4정도 줄였다.

• 제어로봇시스템학회논문지
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• 제21권7호
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• pp.669-676
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• 2015

In this paper, we described the simulation results of the phase offset performance of a clock in holdover mode which was normally operated in GPS Disciplined Oscillator (GPSDO). In the TIE model, we included the time error term caused by environmental temperature variation because one of the most important parameters of clock phase error is the frequency offset and drift caused by the variation of temperature. For the simulation, we employed Maximum Time Interval Error (MTIE) for the performance evaluation when the frequency offset and drift are estimated by using an Unbiased Finite Impulse Response (UFIR) filter with ladder algorithm. We assumed that the noise in the GPS measurement is white Gaussian with zero mean and 1 ns standard deviation, and temperature linearly varies with a slope of $1{^{\circ}C}$ per hour. From the simulation results, the followings were observed. First, with the estimation error of temperature of less than 3 % and the temperature compensation period of less than 900 seconds, the requirement of CDMA2000 phase synchronization under 10 us could be achieved for more than 40,000 seconds holdover time if we employ an OCXO (Oven Controlled Crystal Oscillator) clock. Second, in order to achieve the requirement of LTE-TDD under 1.5 us for more than 10,000 seconds holdover time, below 3 % estimation error and 500 seconds should be retained if a Rubidium clock is adopted.

• 디자인학연구
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• 제15권3호
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• pp.29-38
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• 2002

최근 모바일 휴대폰을 이용한 서비스 종류는 기하급수적으로 증가하고 있다. 또한 잦은 휴대폰 기기의 교체와 통신 서비스 회선의 변경으로 인하여 사용자들은 그 어느 때보다도 모바일 서비스 이용에 어려움을 겪고 있다고 할 수 있다. 그러나 정작 도움을 주어야 하는 매뉴얼은 휴대폰 사용 상황의 특성상 큰 도움을 주지 못하고 있는 실정이다. 모바일 휴대폰에는 1) 휴대폰 기기 자체기능, 2) 인터넷 서비스 기능, 및 3) 통신회선 자체 서비스 기능 등이 혼재되어 있고, 주로 이동 중에 사용되므로, 매뉴얼 이용 공간과 사용자 기능습득의 공간이 일치하기 힘들다는 점이 두드러진다. 따라서 바람직한 모바일 휴대폰의 사용자 매뉴얼은 모바일 휴대폰 시스템 자체 내에서 포괄적으로 포함하는 것이 바람직한 모델이다. 본 연구는 이러한 시스템 자체 내에서 활용될 수 있는 사용자 매뉴얼의 가능성에 주목하고, 1) 전자 매뉴얼의 정보 표현 방식과 그에 대한 사용자의 반응을 조사하고, 2) 사용자의 정보습득 패턴을 분석하여 3) 시각적 단서(Visual Cue)의 제공이 사용자 매뉴얼 사용의 편의성을 향상시킴을 발견하여 이를 모바일 핸드폰에 활용하기 위한 가이드라인을 개발함을 그 목적으로 하였다.

• 마케팅과학연구
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• 제19권4호
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• pp.11-23
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• 2009

HSDPA（高速下行分组接入）是在第三代的W－CDMA技术基础上的3.5代移动通信异步服务. 在韩国, 它主要是通过提供可视电话服务. 由于更强大和多元化的服务扩散, 随着移动通信技术迅速的进步, 消费者需要更多的选择. 然而, 由于各种技术, 不论消费者偏好往往会溢出市场, 消费者感到越来越迷惑. 因此, 我们不应该采取只注重发展假设是下一代新技术项目的战略相反, 我们应该了解消费者接受新的形式和技术的过程, 通过制定战略, 使开发人员能够理解并提供消费者真正想要的, 从而降低进入市场的障碍. 在技术接受模型（TAM）中, 感知到的有用性和使用的简单性被认为是影响人们接受新技术的态度的最重要因素(Davis, 1989; Taylor and Todd, 1995; Venkatesh, 2000; Lee et al., 2004). 感知到的有用性是一个人相信某种特定的技术能提高他或她工作绩效的程度. 感知易用性是主观认为使用某种特定技术不需要太多体力和精力的付出的程度(Davis, 1989; Morris and Dillon, 1997; Venkatesh, 2000). 感知的愉悦性和感知的有用性已经被清楚的证明对接受技术的态度有影响(Davis et al., 1992). 比如, 网上购物的愉悦性已经表现出对消费者对网上商家的态度有积极的影响(Eighmey and McCord, 1998; Mathwick, 2002; Jarvenpaa and Todd, 1997). 消费者的感知风险是一种主观风险. 这种风险和客观可能的风险是有显著区别的. 感知风险包括心理上的风险, 这是当消费者为某一特定物品而选择品牌, 商店和购买方式时所感知到的. 企业革新产品的能力取决于有效的获得有关新产品的知识(Bierly and Chakrabarti, 1996; Rothwell and Dodgson, 1991). 知识获取是公司感知外界新事物和技术的价值的能力(Cohen and Levinthal, 1990); 是公司评估外界最新的技术的能力(Arora and Gambaradella, 1994); 是公司正确预测这项科技对未来革新的能力(Cohen and Levinthal, 1990). 消费者创新是一种在社会体系中比其他人更早接受创新的程度(Lee, Ahn, and Ha, 2001; Gatignon and Robertson, 1985). 也就是说, 它显示了消费者如何快速、方便地接受新的思路. 创新被认为是重要的, 因为它对消费者是否接受新产品和他们多快接受新产品有显著的影响(Midgley and Dowling, 1978; Foxall, 1988; Hirschman, 1980). 我们用技术接受模型来进行跨国家的研究比较, 此模型实证验证了影响态度的因素-感知有用性, 易用性, 感知愉悦, 感知风险, 创新和感知的知识管理水平-和对ＨＳＤＰＡ服务的态度之间的关系. 我们为HSDPA服务提供商开发更有效的管理方法还验证了态度和使用意图之间的关系. 在本研究中, 我们在韩国350名学生中分发了346份问卷调查. 由于其中26份收回的问卷时不完整的或者有缺失数据, 所以在假设检验时320份问卷被使用. 在英国, 200份问卷收回了192份, 舍弃了两份不完整的之后, 总共有190份问卷用于统计分析中. 整体模型的分析结果如下: 韩国, x2=333.27(p=0.0), NFI=0.88, NNFI=0.88, CFI=0.91, IFI=0.91, RMR=0.054, GFI=0.90, AGFI=0.84; 英国, x2=176.57(p=0.0), NFI=0.88, NNFI=0.90, CFI=0.93, IFI=0.93, RMR=0.062, GFI=0.90, AGFI=0.84. 在韩国消费者中, 从有关影响HSDPA服务的使用意图和态度之间的关系的假设检验的结果中, 感知的有用性, 易用性, 乐趣, 知识管理的高水平和促进创新对HSDPA移动手机的态度有积极的影响. 然后, 易用性和感知的乐趣对HSDPA服务的使用意图没有直接的影响. 这可能是因为在日常生活中使用视频电话还不是必需的这一现实. 而且消费者对ＨＳＤＰＡ视频电话的态度和使用意图有直接的关系, 这些态度包括感知的有用性, 易用性, 乐趣, 知识管理的高水平和创新. 这些关系构成了购买意图的基础, 并造成消费者决定谨慎购买的情况. 对欧洲消费者的假设检验结果揭示了感知的有用性, 乐趣, 风险和知识管理水平是影响态度形成的因素, 而易用性和创新则对态度没有影响. 特别是效果价值和感知有用性, 在快乐和知识管理之后对态度有最大的影响. 相反, 认为感知风险对态度影响较小. 在亚洲模型中易用性和感知的乐趣没有发现对使用意图有直接影响. 然而, 因为态度广泛的影响使用意图, 感知有用性, 乐趣, 风险和知识管理可被视为从使用意图中的态度发展的关键因素. 总之, 感知的有用性, 愉悦和知识管理水平在亚洲和欧洲消费者中对态度形成都有影响, 这些梯度形成了消费者的使用意图. 而且, 易用性和感知的乐趣对使用意图的假设被拒绝. 然而, 易用性, 感知风险和创新有不同的结果. 在亚洲消费者中, 感知风险对态度形成没有影响, 而在欧洲消费者中, 易用性和创新对态度都没有影响.

• 무역상무연구
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• 제13권
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• pp.869-895
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• 2000

The US supports the Information and Communication (IC) industry as a strategic one to wield a complete power over the World Market. However, several other countries are also eager to have the support for the IC industry because the industry produces a high added value and has a significant effect on other industries. Korea is not an exception. Korea recently succeeded in the commercialization of CDMA for the first time in the world, after the successful development of TDX. Hence, it is highly likely to get tracked by the US. Although the IC industry is a specific sector of IT, there is a concern that there might be a trade friction between the US and Korea due to a possible competition. It will be very important to prepare a solution in advance so that Korea could prevent the friction and at the same time increase its share domestically and globally. It will be our important task to solve the problem with the minimum cost if the conflict arises unfortunately in the IT area. The parties that have a strong influence on the US trade policy are the think tank group and the IT-related interest group. Therefore, it would be important to have a close relationship with them. We found some implications by analyzing the case of Japan, which has experienced trade frictions with the US over the long period of time in the high tech industry. In order to get rid of those conflicts with the US, the Japanese did the following things : (1) The Japanese government developed supporting theories and also resorted to international support so that the world could support the Japanese theories. (2) Through continual dialogue with the US business people, the Japanese business people sought after solutions to share profits among the Japanese and the US both in the domestic and in the worldwide markets. They focused on lobbying activities to influence the US public opinion to support the Japanese. The specific implementation plan was first to open culture lobby toward opinion leaders who were leaders about the US opinion. The institution, Japan Society, were formed to deliver a high quality lobbying activities. The second plan is economic lobby. They have established Japanese Economic Institute at Washington. They provide information about Japan regularly or irregularly to the US government, research institution, universities, etc., that are interested in Japan. The main objective behind these activities though is to advertise the validity of Japanese policy. Japanese top executives, practical interest groups on international trade, are trying to justify their position by direct contact with the US policy makers. The third one is political lobby. Japan is very careful about this political lobby. It is doing its best not to give impression that Japan is trying to shape the US policy making. It is collecting a vast amount of information to make a correct judgment on situation. It is not tilted toward one political party or the other, and is rather developing a long-term network of people who understand and support the Japanese policy. The following implications were drawn from the experience of Japan. First, the Korean government should develop a long-term plan and execute it to improve the Korean image perceived by American people. Second, the Korean government should begin public relation activities toward the US elite group. It is inevitable to make an effort to advertise Korea to this elite group because this group leads public opinion in the USA. Third, the Korean government needs the development of a relevant policy to elevate the positive atmosphere for advertising toward the US. For example, we need information about to whom and how to about lobbying activities, personnel network who immediately respond to wrong articles about Korea in the US press, and lastly the most recent data bank of Korean support group inside the USA. Fourth, the Korean government should create an atmosphere to facilitate the advertising toward the US. Examples include provision of incentives in tax on the expenses for the advertising toward the US and provision of rewards to those who significantly contribute to the advertising activities. Fifth, the Korean government should perform the role of a bridge between Korean and the US business people. Sixth, the government should promptly analyze the policy of IT industry, a strategic area, and timely distribute information to industries in Korea. Since the Korean government is the only institution that has formal contact with the US government, it is highly likely to provide information of a high quality. The followings are some implications for business institutions. First, Korean business organization should carefully analyze and observe the business policy and managerial conditions of US companies. It is very important to do so because all the trade frictions arise at the business level. Second, it is also very important that the top management of Korean firms contact the opinion leaders of the US. Third, it is critically needed that Korean business people sent to the USA do their part for PR activities. Fourth, it is very important to advertise to American employees in Korean companies. If we cannot convince our American employees, it would be a lot harder to convince regular American. Therefore, it is very important to make the American employees the support group for Korean ways. Fifth, it should try to get much information as early as possible about the US firms policy in the IT area. It should give an enormous effort on early collection of information because by doing so it has more time to respond. Sixth, it should research on the PR cases of foreign enterprise or non-American companies inside the USA. The research needs to identify the success factors and the failure factors. Finally, the business firm will get more valuable information if it analyzes and responds to, according to each medium.