• Journal of Positioning, Navigation, and Timing
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• v.5 no.1
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• pp.11-20
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• 2016

In this paper, a system that can collect GPS L1 C/A, GLONASS G1, and BDS B1I signals with single front-end receiver was implemented using a universal software radio peripheral (USRP) and its performance was verified. To acquire the global navigation satellite system signals, hardware was configured using USRP, antenna, external low-noise amplifier, and external oscillator. In addition, a value of optimum local oscillator frequency was selected to sample signals from three systems with L1-band with a low sampling rate as much as possible. The comparison result of C/N0 between the signal collection system using the proposed method and commercial receiver using double front-end showed that the proposed system had 0.7 ~ 0.8dB higher than that of commercial receiver for GPS L1 C/A signals and 1 ~ 2 dB lower than that of commercial receiver for GLONASS G1 and BDS B1I. Through the above results, it was verified that signals collected using the three systems with a single USRP had no significant error with that of commercial receiver. In the future, it is expected that the proposed system will be combined with software-defined radio (SDR) and advanced to a receiver that has a re-configuration channel.

• Proceedings of the KIPE Conference
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• 2012.11a
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• pp.251-252
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• 2012

ITER(국제핵융합실험로) 제어시스템은 중앙제어와 Plant System으로 구성되며 CODAC, Central Interlock, Central Safety System으로 구분된다. 초전도자석에 전류를 공급하는 AC/DC 컨버터 시스템은 2상한, 4상한 구조의 전원 장치, 초기 플라즈마 발생에 필요한 Switching Network Unit, 코일에 저장된 에너지의 급속 방전을 위한 Fast Discharge Unit 및 무효 전력 보상장치로 구성된다. 4상한 전원장치는 1, 2, 4, 6대의 전원 장치가 직렬 접속되어 무효전력 발생이 최소로 하도록 제어된다. 대용량의 무효전력이 급격히 변화는 환경에서 계통 전압을 유지하기위해 무효전력보상장치는 각 전원 장치가 예측한 무효전력 값을 이용하여 제어한다. 본 논문은 ITER 전원 장치를 운전하기 위한 제어시스템의 개요와 예비설계 결과이다.

• Journal of Nutrition and Health
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• v.24 no.3
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• pp.230-242
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• 1991

This research was conducted on the 10 take-out boxed-lunches commercially prepared in the department stores. chain stores. and the public railroad trains in Korea. Sampling was conducted from February 1990 to March 1990. Nutritive values and sodium contents of the 10 boxed-lunch samples are summarized as follows : 1) The average weight(percentage) of the cooked rice and the side dishes were 304.6g(49.4) and 312.4(506%), respectively. The weight of these samples were significantly heavier than that of Japanese style boxed-lunches. 2) The average number of the side dishes was 12. The average numbers of food items classified by the five food groups were 6.1 in protein food group, 0.3 in calcium food group. 6.0 in vitamin and mineral food group. 1.5 in carbohydrate food group, and 1.5 in oil and fat food group. 3) They contained on the average 840.7kcal of energy, 38.9g of protein, 22.7g of fat, 120.4g of carbohydrate. 300.8mg of calcium. 410.8mg of phosphours, 6.61 mg of iron. 219.8 R.E. of vitamin A, 0.46mg of thiamin, 0.67mg of riboflavin, 10.5mg of niacin, 27.5mg of ascorbic acid. Thus. except vitamin t the content of all the nutrients were higher than the value of 1/3 of the RDA for adults. 4) The high priced group(group 2) had more protein, calcuim. iron and niacin contents than the cheaper group(group 1). Probably, it's because the group 2 had more animal foods than the group 1. 5) The average energy content per unit price(100 won) was 37.3kcal and the average protein content per unit price(100 won) was 1.64g. Korena style boxed-lunches had higher energy and protein contents per unit price than Japanese style, and the group 1 higher than the group 2. 6) The average energy Proportions of Protein, carbohydrate. and fat were 18.3%, 57.4%, and 24.3%, respectively. These proportions are good enough. 7) Frequency of cooking methods for the side dishes were found in the decreasing order : pan-frying, frying, braising, seasoning, kimchi, grilling, pickling, stir-frying, steaming and fermenting. Generally simple cooking methods were used, thus the menus were lack or varieties. 8) Frequency of colors for the side dishes were found in the decreasing order : red, brown. yellow, green, black, white. Too much red pepper was used. 9) The average capacity of the containers for the staples and the side dishes were 468.1ml and 590.6ml, respectively. And the containers could not keep the food items well seperated. 10) The average contensts of sodium and salt were 2.287mg and 5.76g, in the range of 1, 398mg to 3, 489mg and 3.53g to 8.80g, respectively. These are much higher values than the recommended amount of salt.

• Transactions of the Society of Information Storage Systems
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• v.2 no.3
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• pp.178-183
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• 2006

A Blu-ray disc, which has a more than 25GB optical capacity, has been known as a promising next-generation optical disc format. It commonly has a 1.1 mm thick substrate and a 0.1 mm thick cover layer for beam transmitting and the protection of the reflecting surface. The cover layer is generally formed by the spin coating process. However, in conventional spin coating, small bumps are formed along the rim of the disc, which results in the fatal reading error. Numerical simulation of the thin film flow behaviors during spin coating with the commercial solver and optimal spinning conditions was obtained. Thickness distribution of the cover layer according to the variation of substrate's edge shape could be calculated as well. By modifying the shape of the substrate edge shape, the bumps along the disc rim could be minimized, and it was proved that the chamfered edge, around $5{\sim}10$ degree, is the simplest and most effective way to minimize the bumps.

• Transactions of the Korean Society of Automotive Engineers
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• v.13 no.2
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• pp.72-82
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• 2005

The objective of this paper is to describe the optimization of design parameters in a large-sized commercial bus heater system by using CFD(computational fluid dynamics) analysis and Taguchi method. In order to obtain the best combination of each control factor which results in a desired performance of heater system, the parameter design of the Taguchi method is adopted for the robust design considering the dynamic characteristic. The research activity may be divided into four phases. The first one is analyzing the problem, i.e., ascertaining the influential factors. In the second phase the levels were set in such a way that their variation would significantly influence the response. In the third phase the experimental runs were designed. In the final phase the planned runs were carried out numerically to evaluate the optimal combination of factors which is able to provide the best response. In this study, eight factors were considered for the analysis: one with two level and seven with three level combinations comprising the $L_{18}(2^1{\times}3^7)$ orthogonal array. The results of this study can be summarized as follows ; (i)The optimum condition of control factor is a set of <$A_2\;B_1\;C_3\;D_3\;E_1\;F_2\;G_3\;H_2$> where A is shape of the outer fin, B is pitch of the outer fin, C is height of the outer fin, D is the inner fin number, E is the inner fin height, F is length of the flame guide, G is diameter of the heating element and H is clearance between air guide and heating element. (ii)The heat capacity of heated discharge air under the optimum condition satisfies the equation y=0.6M w here M is a signal factor. (iii)The warm-up rate improves about three times, more largely as com pared with the current condition, which results in about 9.2minutes reduction.

• Journal of the Korean BIBLIA Society for library and Information Science
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• v.6 no.1
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• pp.133-160
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• 1984

The main purpose of the present study is to survey the major abstracting bulletins of national nature in Korea, to define such problem areas as lacunae, duplicates and limitation in coverage in the abstracting services currently available in Korea, and to make some suggestions for action for improving the abstracting services in the light of general principles and the tradition and situations unique to Korea. The major conclusions reached at this study are summarised as follows: (A) A new abstracting bulletin of general nature covering the whole field needs to be created in each of the following fields where no established abstracting service is available for the outcome of research and development activities in Korea. (1) Language (2) Religion (3) Art (4) Language (5) Literature (6) History (B) A new specialised abstracting bulletin needs to be created in each of the following fields of science where abstracting services limited in coverage are partially available. (a) Statistics (b) Sociology (c) political science (d) Public administration (e) Law (f) Folk lore (g) Military science (2) Pure sciences (a) Mathematics (b) Chemistry (c) Astronomy (d) Geology (e) Mineralogy (f) Life sciences (g) Botany (h) Zoology (3) Applied sciences (a) Agriculture (b) Architectural engineering (c) Mechanical engineering (d) Electrical engineering (e) Chemical engineering (f) Manufacturing industry (g) Domestic science (C) Publication of the abstracting bulletins suggested in (A) and (B) above may be ideally carried on by a qualified learned society established in the respective field. and should be financially supported by the public fund under the provisions of Art. 27 of the Research Promotion Act of 1979. (D) The current practice of adding the author's abstract and keywords to each of the records of the "Doctoral Theses in Humanities and Social Sciences" part of the" Catalogue of Doctoral and Master's Theses Submitted to the Universities in Korea" published by the National Assembly Library should be applied to all the other parts, i. e. to the parts of the "Master's Theses in Humanities and Social Sciences" and of the "Doctoral and Master's Theses in Natural Sciences': which will not only increase the Catalogue's use value but also discourage appearance of various theses abstracts of individual academic institutions such as the" Abstracts of the Doctoral and Master's Theses Submitted to Korea Advanced Institute of Science and Technology" which will in turn reduce inefficiency involved in the abstracting services at national level. (E) A general abstracting bulletin covering most part of the outcome of research and development activities in Korea other than that covered by the existing abstracts needs to be created to be temporarily. used till the abstracting journals suggested in this study will be fully available. A realistic way of having such a bulletin may be to expand the present coverage of "The Abstracts of the Reports of the Government-sponsored Projects" currently published by Korean Research Foundation.

• Transactions of the Korean Society of Mechanical Engineers
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• v.11 no.6
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• pp.1036-1043
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• 1987

The objective of this paper is to improve the transient response characteristics of hydraulic servosystem via a reduced-order observer which is modelled based upon the nonlinear hydraulic servosystem. The observer is a second order linear model and implemented using a 8 bit micro-computer. The performance of the observer-based hydraulic servosystem was investigated through the hybrid computer simulations and experiments. The result shows that the reduced-order observer can effectively improve the transient response characteristics of hydraulic servosystem.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.9 no.2
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• pp.91-99
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• 2001

오늘날 위성항법, 위성통신을 이용한 항공항법감시의 새로운 변화 가운데 국제민간항공기구(ICAO)에서 VDL(VHF Digital Link) Mode 4로 채택된 STDMA (Self-organized Time Division Multiple Access)에 관심이 증대되고 있다. 해양분야에서는 선박위치 자동인식시스템(AIS) 및 선박운행관리시스템(VTS)에서 2002년부터 적용될 예정이고, 항공분야에서는 향후 몇 년후에는 ADS-B, SMGCS에서 응용될 가능성이 높다. 본 연구에서는 STDMA를 이용한 SMGCS구현을 위한 기술개발로서 사전에 측지된 기준국으로부터 실시간으로 GPS 보정값을 생성, 전송하도록 하는 실시간 DGPS기술과 동기신호에 따라 시분할 다중접속을 구현한 소프트웨어 기반의 TDMA기술을 구현하였으며 이를 연구원내에서 차량이동 실험을 수행하여 다수의 이동국간에 측위값을 상호전송함으로써 각각의 위치를 실기간으로 파악할 수 있음을 보였다.

• Electronics and Telecommunications Trends
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• v.19 no.3 s.87
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• pp.1-11
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• 2004

본 고에서는 차세대 이동통신 중 특히 무선전송과 관련한 표준화 및 국내외 기술개발 동향을 살펴보고자 한다. 이를 위해 IMT-2000 규격 표준화를 위해 설립된 3GPP와 3GPP2의 동향을 먼저 살펴보고, 다음으로 북미의 LAN/MAN 표준화 단체인 IEEE 802와, IMT-2000 진화 시스템 및 B3G 시스템 연구를 진행중인 ITU-R WP8F의 활동을 소개한다. 또한 차세대 이동통신 관련 기술에 대한 연구와 표준화 준비를 위해 설립된 포럼들, 즉 유럽 중심의 WWRF, 일본의 mITF, 한국의 GMC 포럼 등의 현황을 살펴보고, 마지막으로 북미, 유럽, 일본 및 중국 등 외국과 국내의 차세대 이동통신 기술개발 동향을 소개한다.

• Journal of computational fluids engineering
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• v.14 no.2
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• pp.39-45
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• 2009

In engine room, proper enclosure system is preferable for reducing noise level but the enclosure system in the engine room causes bad influence on cooling performance due to poor ventilation. Cooling efficiency of the enclosure system can be improved by varying fan speed and proper flow path for ventilation. In this study, numerical analysis is performed to assess cooling effect of the enclosure system using finite volume method. The RNG k-$\varepsilon$ model is adopted for turbulence model along with heat exchanger model and porous media model for heat exchanger analysis, and moving reference frame model for rotational fan. Verification result shows reasonable agreement with experimental data. Analysis results show direct effect of velocity and temperature distribution on cooling ability in the enclosure system. Enclosure system of case B shows high heat transfer coefficient and has the smallest area ratio of opened flow passages which is good for noise level reduction.