• Journal of the Institute of Electronics Engineers of Korea TC
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• v.38 no.8
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• pp.19-29
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• 2001

The recent explosion in the Internet applications, Internet. host number and the traffic in the IP backbone network is posing new challenges for transport network. This requires a high-speed IP backbone network that has a substantially higher bandwidth than the one offered by current networks, which prompts the development of all-optical network. To obtain optical network utilization gains, we need a software which establishs logical topology to make possible the efficient use or physical topology, and control the optical network in combination with the IP layer routing protocols. Finally, the logical topology is required higher efficient than physical topology. For this an efficient algorithm for the routing and wavelength assignment(RWA) in the WDM all-optical network is necessary. In this paper, two kinds of heuristic algorithms to establish logical topology for WDM networks and arc applied to the design of logical topology of domestic backbone network. These algorithms are found to work quite well and they arc compared with each other in terms of blocking rate, etc.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.18 no.11
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• pp.2651-2657
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• 2014

It can be organized with PVRs and FC-AL for a high-quality TV content-sharing architecture. It is, however, not easy to configure a large community network with the FC-AL since it has a 7-bit address space with supporting up to 127 users. We, therefore, propose a novel scalable FC-AL multiple-loop architecture using shared disks, which does not need to use expensive and load-concentrated switches. In this article, our suggested architecture shows a superb startup delay, such as less than 20msec. In addition, it demonstrates outstanding scalability, such that the number of accomodable users increases almost linearly according to adding loops. Lastly, it reveals exceptional time-shifting hours, that is, which supports more than 140 hours with 1000 users.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.8 no.2
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• pp.265-275
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• 2004

In this paper, an OFDM-CDMA broadband system is considered for a possible candidate of fixed wireless broadband access network applications. With an emphasis on a preamble design for multi-channel separation, we address a channel estimation based on the time-domain windowing and its imperfectness in OFDM-based multiple-antenna transmission systems. By properly designing each preamble for multiple antennas to be orthogonal in the time domain, the channel estimation can be applied to the ETSI HlPERLAN/2 and IEEE-802.11a standards in the case of more than two transmit antennas. Also, an effect of diversity techniques on the performance of OFDM-CDMA based broadband wireless access networks is investigated and the maximum achievable diversity gain for a two-path Rayleigh fading environment is evaluated Simulation results show that the OFDM-CDMA system applying a space-time-frequency diversity with a full-rate full diversity code can give the diversity of D = 4 and D = 8 for both multi-user cases of maximum user and half user capacities, respectively.

• Journal of Korea Water Resources Association
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• v.44 no.1
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• pp.1-8
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• 2011

This paper addresses the correlation between the flood damage cost and recovery cost. National data (15 regions) for 20 years, panel data, has been analyzed for this test. Model specification of panel data analysis depends on the characteristics of data set and "fixed" or "random" effects model can be used. The results are represented in both models. As we expected all independent variables show positive relationship with recovery cost, except for the number of death and suffers. The damage of public facilities, such as rivers and road are the major factors on the damage and recovery cost, which means that flood damage can not be decreased without decreasing damages of public facilities from floods. Especially, the recovery cost is always higher than the damage cost and investment for flood control. Unlikely, government investment for flood control is the highest and recovery cost is the always lower than da mage cost andinvestment in Japan. Which means that proper investment can reduce economic damage cost of flood and recovery cost.

• Journal of Korean Society of Transportation
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• v.21 no.4
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• pp.103-111
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• 2003

This study proposes methodology deterimining a basic pedestrian crossing capacity that plays a critical role in the installation of pedestrian signal at the crosswalks. The methodology is based on the pattern of vehicle arrived at the crosswalks. Erlang distribuion is used as headway distribution that can cover the various levels of flow rate. Models using Erlang distribution are represented by Erlang parameter (K) of 1, 2, or 3 at 2-, 4-, or 6-lane roadway in both directions. In addition, this study considered the only type of road with a pedestrian refuge area in the median that is used to wait for the allowable gap provided by the flow of another direction. As a result, the pedestrian capacity decreases as flow rate increases and Erlang parameter increases for the road with the pedestrian refuge. This study develops the models to determine the pedestrian capacity under a variety of flow rates and the outcomes of this study could be used as the criteria for the determination of the installation of pedestrian signal or for the provision of pedestrian refuge in the median of road.

• Proceedings of the Korea Water Resources Association Conference
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• 2019.05a
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• pp.417-417
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• 2019

하천의 기능은 공학적 관점에서의 이수, 치수, 환경 기능 외에도 사회적 관점에서 역사 문화 기능을 포함할 수 있다(우효섭, 2009). 1990년대 말부터 하천복원사업이 본격화 되면서 최근에는 하천환경 기능 외에도 친수를 포함한 역사 문화 기능이 하천관리의 주요 축으로 고려되거나 포함되고 있다. 이 과정에서 하천의 역사 문화 기능을 주문하는 요구가 증가한 이유로는 하천복원사업의 지역적 획일화, 친수(심미) 요구 증대, 지역 경제성 제고, 환경(생태, 문화 등) 가치 증대 등 사회경제적 정책적 환경 변화가 기인한 부분이 크다고 할 수 있다. 이러한 측면에서 볼 때 하천의 지속가능하고 효과적인 관리와 보전을 위한 방안으로 하천의 역사 문화적 요소를 사회 경제적, 생태 환경적 요소와 연계하는 접근방식은 유용할 수 있다. 이를 위해서는 우선적으로 지역공동체가 형성해온 물 문화의 특수성을 감안하여 하천유역의 역사 문화적 소재 및 자원을 발굴할 필요가 있다. 그리고 조사 수집된 다양한 역사 문화적 소재 및 자원은 하천사업 및 관리의 주요 콘텐츠로 활용되기 위한 창출과정을 진행함으로써 사회 경제적, 생태 환경적 요소와 연계할 수 있다. 본 연구에서는 하천유역을 대상으로 문헌조사 기반의 사전조사와 심도 있는 현장조사(탐문조사 등) 수행결과를 토대로 향후 하천복원사업에 활용될 수 있는 다양한 역사 문화적 소재와 자원 등에 관한 콘텐츠를 도출하였다. 또한 콘텐츠 활용방안은 하천 역사 문화 자원의 세부적인 콘텐츠를 아우를 수 있는 테마설정을 통하여 대상지 및 지역특성(치수 안전, 지역요구, 물 문화 가치 등) 등을 고려한 방안을 제시하였다. 특히, 친수 측면에서 현재 수변공간을 이용하는 방문자수, 목적(산책, 스포츠, 낚시, 물놀이, 레저 등) 등에 대한 패턴과 지역 인구 현황, 접근 인프라(교통, 이동로, 편의시설 등), 주민 요구도 등 잠재적 친수도는 물 문화 형성이라는 측면에서 볼 때 주요한 고려사항이라 할 수 있다.

• Korea Real Estate Review
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• v.28 no.3
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• pp.79-94
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• 2018

This study analyzed the factors associated with residential mobility based on the data from the 11th to the 19th wave of the Korean Labor & Income Panel Study (KLIPS). After grouping low-income households within the first to the fourth income bracket into households that exhibited no income bracket change and those with income bracket changes during the research period, this study examined the effects of the income situation of each group on residential mobility. According to the results of the analysis, in the group of households that showed no low-income bracket change, significant effects were found only in the age of the head of the household, housing cost, and rental deposit (Jeonse) and monthly rental of the household. In the group of households that showed low-income bracket changes, findings were generally in line with those of the whole household, where total income and the number of full-time employees in the household were the same as those of the whole household, indicating that it would be necessary to improve the employment stability of low-income households. Based on the findings of this study, housing inequality is intensifying within low-income households, and, thus, housing policies, based on continuing surveys, must be implemented to enhance income opportunities and stabilize the housing needs of low-income households.

• Journal of the Korea Institute of Construction Safety
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• v.2 no.1
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• pp.9-15
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• 2019

Despite the efforts for enhancing the safety record, construction industry has been suffered from higher fatalities than other industries. The poor record of safety in construction industry means that there is a clear need for an effective countermeasure. As mentioned in previous studies, it is important to identify the type of activities or risks that are likely to cause accidents and to develop appropriate safety measures. Considering the large number of accident cases on the temporary installations including work platforms and work passages, the temporary installations should be managed first. To support it, this study aims to analyze falling accident cases on construction working platforms and passages which can lead to develop proper safety measures. Through the analysis of 1663 accident cases in the perspective of cost, progress, activity, and type of workers, this study identifies how the recent accidents occur and what is the cause of the accident occurrence. The identified causes of accident occurrence will help us to improve current construction safety.

• Journal of radiological science and technology
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• v.41 no.6
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• pp.533-538
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• 2018

As the use of digital radiographic system has been expanded, there are some concerns an increase about in patient of radiation dose. Therefore, International Electro-technical Commission (IEC) has been proposed a standard foe exposure index (EI). In this study, the EI was measured on human chest model using computed radiography (CR). Radiation quality used RQA5 of IEC62494-1. After acquiring the chest anterior posterior image (Chest AP) by using the phantom, the EI was obtained by applying the system response. In this study, we have analyzed the images with the detector size (Full filed ROI) and the optimized image (Fit filed ROI). The EI increased proportionally with radiation dose increase. Due to the discrete increase in pixel value, the EI showed an exponential increase. The discrete increase in noise equivalent quanta (NEQ) resulted in a discrete increase in the EI. The EI of the two images used in this study increased with increasing NEQ but showed different increments. For the measurement of the EI, IEC standards must be followed. The EI should be used as an index to evaluate the image quality for quality control of X-ray image rather than as an indicator of exposure dose. When calculating the EI, the system response should be applied depending on whether or not the grid is used. The size of the field should be obtained by including only the necessary parts.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2014.10a
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• pp.917-920
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• 2014

In Korea mobile phone subscribers exceeded 1 million people in 1995, and ten million people in 1998. Prevalence of the mobile phone increased dramatically over 110% compared to the population. And all family members including children and students use one or two mobile terminal. Mobile phone is obviously necessary good more than washer, vacuum cleaner, passenger car. Our daily life with mobile communication are conveniently positioned, but communication related costs including the price of the device has become a big burden on the household. But the government does not seem to do the right role at the right time to prevent the failure of the market to further maximize consumer welfare and social welfare through fair competition. This principal-agent problems exist especially in perspective of joint use of the mobile communication network, number portability, separation of phone distribution and phone service and network neutrality among in mobile communication policies since the early 1990s up to now.