• Journal of the Korean Society of Safety
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• v.18 no.3
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• pp.88-93
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• 2003

The Process Safety Management (PSM) by the Law of Industry, Safety and Health has been performed for preventing major accidents of chemical plants since 1996. In terms of preventing chemical accidents more precisely, it is essential to develop a tool for quantitative risk assessment. For this, KOSHA (Korea Occupational Safety and Health Agency) developed an Integrated Risk Management System (IRMS). The system is designed to assimilate data on chemical plant hazards from external database, to integrate these data with location information(topographic and demographic), and to make them user-friendly accessible. The system consists of several main functions: display of five major Korean petrochemical complex layout display of equipment layout with its information utilizing the external database, zonation of the hazard effected area with consequence analyses, the most probable accident scenario generation, accident/incident database and calculation of frequency of accident using equipment reliability database, etc. The highlight of IRMS is to provide the risk contours using GIS(Geographical Information System) technology. IRMS is intended to manage hazardous installation more systematically and effectively, to reduce the number of accident remarkably, further minimizing production loss in the plant. The system is now under application to about 500 PSM sites as well as and emergency authorities in Korea by KOSHA (Korea Occupational Safety and Health Agency)

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2017.10a
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• pp.543-545
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• 2017

This paper describes the SAO hardware architecture design for high performance in-loop filters. SAO is an inner module of in-loop filter, which compensates for information loss caused by block-based image compression and quantization. However, HEVC's SAO requires a high computation time because it performs pixel-unit operations. Therefore, the SAO hardware architecture proposed in this paper is based on a $4{\times}4$ block operation and a 2-stage pipeline structure for high-speed operation. The information generation and offset computation structure for SAO computation is designed in a parallel structure to minimize computation time. The proposed hardware architecture was designed with Verilog HDL and synthesized with TSMC chip process 130nm and 65nm cell library. The proposed hardware design achieved a maximum frequency of 476MHz yielding 163k gates and 312.5MHz yielding 193.6k gates on the 130nm and 65nm processes respectively.

• The Transactions of the Korean Institute of Power Electronics
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• v.9 no.5
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• pp.457-466
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• 2004

In this paper, a modified converter is presented and analyzed to use as a photovoltaic converter. And also a new parallel driving scheme is proposed to increase output power and to reduce the output voltage ripple. The ratio of the output to the input voltage of the modified converter is equal to that of the boost converter. The difference between both converters is the composition of output terminal. Owing to the discrepancy, a working voltage of the output capacitor of the modified converter becomes lower, thus the capacitance value of the capacitor can be smaller than that of the boost converter. The proposed parallel driving is based on the modified converter and a current-mode-control method. It gives a good solution for alleviating the current sharing unbalance problem of conventional parallel operations. It reduces the output voltage ripple by means of increasing the equivalent switching frequency without additional switching losses. The validity of the proposed parallel driving strategy is verified through computer-aided simulations and experimental results.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.11a
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• pp.459-459
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• 2007

VHF ICP (Very High Frequency Inductively Coupled Plasma) 반응기에서 반응기 압력, 수증기 유량, 플라즈마 출력, 반응기온도 등의 공정변수에 따른 수증기 분해특성과 수소생성거동을 실험하였다. 플라즈마 분해 특성은 OES(Optical Emission Spectroscopy)를 사용하여 분석하였으며, QMS(Quadrapole Mass Spectroscopy)를 이용하여 배기가스 성분을 분석하여, 수증기 분해거동 및 수소생성 효율을 조사하였다. 본 연구실에서 설계한 초고주파 유도결합 플라즈마는 고밀도 플라즈마 생성과 낮은 압력에서도 안정된 플라즈마 발생 특징을 나타내었다. 플라즈마 출력의 증가에 따른 수증기의 분해와 수소생성 거동은 개시영역, 선형증가영역, 포화영역의 세 영역으로 구분되는 특징을 나타내었다. 유량 및 압력의 증가에 따라 포화에 필요한 플라즈마의 출력이 증가되는 경향을 나타내었다. 본 실험의 온도범위에서는 온도 증가에 따른 수증기 분해 및 수소생성 증가효과는 플라즈마 출력의 영향에 비하여 매우 미미한 정도로 플라즈마의 높은 에너지 전달효과를 확인할 수 있었다. 따라서, 낮은 반응기 온도에서도, 유량 및 압력에 따른 포화 플라즈마조건을 설정할 경우, 높은 에너지 효율의 수소 제조가 가능함을 알 수 있었으며, 물분해 플라즈마를 이용한 저온 산화물 박막증착에의 적용도 기대된다.

• Journal of Korean Society of Rural Planning
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• v.11 no.3 s.28
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• pp.19-27
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• 2005

Rural Korea has been becoming heavily aged societies from the end of 20th century due to the massive depopulation of young generation and extension of the average span of human beings. Although rural communities in Korea had been traditionally based on closely webbed social relations, almost all of community self-help organizations disappeared in recent time with very strong urbanization trend. However, almost all rural villages in Korea have the village seniors' union -'NO-IN-HOE' in Korean speaking- of which members usually use, operate and maintain community facilities in terms of voluntary base. Using these facilities, most of public/common/private services and community activities have been being served or provided. So, the purpose of this study is to investigate the usage tendency of community facilities and needs of the rural elderly and to propose the improvement strategies for their optimum usage. For this purpose, data was gathered both from community (107 villages) and individual level surveys(881 older people). The statistical method used for data analysis was descriptive statistics. The major findings were as follows : It was found that the dominant family type of the rural elderly was elderly-only household (75%) with very limited economic capability. There are 2$\sim$3 common community facilities with village including the seniors' center -'KYOUNG-RO-DANG' in Korean speaking. Many of the elderly (74%) use the center once or twice per week. There are several rooms in the center, like as kitchen bathroom and health room, of which usage frequency differs respectively. Many rural elderly want assistance from out-of-village for good maintenance and free use of these facilities.

• Journal of Advanced Navigation Technology
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• v.8 no.2
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• pp.144-154
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• 2004

In this paper we apply the space-time block codes (STBCs), the key technologies for the 4th generation mobile communication systems, to the OFDM system and analyze their performances. First, we derive the signal models for representative STBC schemes and demodulation procedures for each scheme. We also select the parameters for OFDM system considering mobile cellular environments and assign adequate modulation schemes to STBC-OFDM schemes according to the transmission rate from 2bps/Hz to 4bps/Hz. We finally compare and analyze the performances of STBC-OFDM schemes for the selected transmission rates through computer simulations, together with performance comparison when the same modulation scheme being adopted.

• Journal of Advanced Navigation Technology
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• v.14 no.6
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• pp.808-816
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• 2010

Spectrum sharing between wireless systems becomes a critical issue due to emerging new technologies and spectrum shortage. Since WRC-07 allocated 3400-3600MHz band for the coming fourth generation (4G) or IMT-Advanced on a co-primary basis along with existing Fixed Wireless Access (FWA), it requires spectrum sharing studies to solve the interference problems between two systems. In this paper, I propose the separation distance between service coverages as a sharing fundamental criterion based on the interference to noise power ratio (I/N) received in a FWA base station from several IMT-Advanced base stations on the cellular systems. Especially, some results imply that I/N values compared to the worst case can be greatly reduced with MIMO SDMA interference mitigation technique of IMT-Advanced base stations so that these two systems can co-exist in the same frequency with appropriate separation distance.

• KIPS Transactions on Software and Data Engineering
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• v.1 no.2
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• pp.91-102
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• 2012

Computer aided language learning has become popular. But the level of automation of constructing a Korean learning assistant system is not so high because a practical language learning system needs large scale knowledge resources, which is very hard to acquire. In this paper, we propose a Korean learning assistant system that utilizes easily obtainable knowledge resources like a corpus, web documents and a lexicon. Our system has three modules - problem solving, pronunciation marker and writing assistant. Automatic problem generator uses a corpus and a lexicon to make problems with one correct answer and three distracters, then verifies their suitability by utilizing frequency information from web documents. We analyze pronunciation rules for a pronunciation marker and recommend appropriate words and sentences in real-time by using data extracted from a corpus. In experiment, we evaluate 400 automatically generated problems, which show 89.9% problem suitability and 64.9% example suitability.

• KIPS Transactions on Computer and Communication Systems
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• v.3 no.10
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• pp.377-382
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• 2014

Analysis techniques of the data over time from the mobile environment and IoT, is mainly used for extracting patterns from the collected data, to find meaningful information. However, analytical methods existing, is based to be analyzed in a state where the data collection is complete, to reflect changes in time series data associated with the passage of time is difficult. In this paper, we introduce a method for analyzing multi-block streaming data(AM-MBSD: Analysis Method for Multi-Block Stream Data) for the analysis of the data stream with multiple properties, such as variability of pattern and large capacitive and continuity of data. The multi-block streaming data, define a plurality of blocks of data to be continuously generated, each block, by using the analysis method of the proposed method of analysis to extract meaningful patterns. The patterns that are extracted, generation time, frequency, were collected and consideration of such errors. Through analysis experiments using time series data.

• Current Optics and Photonics
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• v.1 no.1
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• pp.23-28
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• 2017

The laser has been regarded as the potential illumination source for the next generation of projectors. However, currently the major issues in applying the laser as an illumination source for projectors are beam shaping and laser speckle. We present a compact solution for both issues by using a vibrating diffractive optical element (DOE). The DOE is designed and fabricated, and it successfully transforms the circular Gaussian laser beam to a low speckle contrast uniform rectangular pattern. Under a vibration frequency of 150 Hz and amplitude of $200{\mu}m$, the speckle contrast value is reduced from 67.67% to 13.78%, and the ANSI uniformity is improved from 24.36% to 85.54%. The experimental results demonstrate the feasibility and potential of the proposed scheme, and the proposed method is a feasible approach to the miniaturization of laser projection display illumination systems.