• 대한전기학회논문지:전력기술부문A
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• 제50권7호
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• pp.303-308
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• 2001

This paper presents algorithm to plan construction and expanding of substation considering contingency accidents by proposing utilization factor according to configuration of substation bank system. In this paper, firstly, proper sphere of supply area by each district which could be standardized with respect to its supply capacity is established under assumption of long term load forecasting. Secondly, goal of utilization ratio based on configuration of substation bank was set to keep reliability by remaining sound bank when it happen to one bank accidents. Finally, it is set up for optimal construction and expanding of substation considering economy and reliability simultaneously about substation to exceed these ratio. To verify proposed algorithm, at first, after adopting a part of Kangnam area in Seoul as area for testing, it is divided into several regions for this area according to power branches of power utility. Secondly, by deriving correlation factor between load demand and economic indicators in these region respectively, the regional load forecasting was performed with economic growth and city plan scenario. Finally, based on the predicted load demand by region and land use data which is identified from air-photographic, the load demand by district was predicted. Also, planning for substation considering contingency is formulated to expand taking into account computing utilization factor which is based on configuration of substation bank respectively.

• 한국환경생태학회지
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• 제28권5호
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• pp.566-573
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• 2014

국가장기생태 연구사업의 일환으로 낙엽활엽수인 신갈나무와 상록침엽수인 소나무 낙엽의 분해율 및 분해과정에 따른 영양염류 함량 변화를 파악하였다. 이를 위해 2005년 12월 월악산의 신갈나무림과 소나무림에 낙엽주머니를 설치하고 2006년 3월부터 2011년 9월까지 69개월간 3개월 간격으로 낙엽주머니를 수거하여 분해율, 분해상수(k), 그리고 분해과정에 따른 C/N비, C/P비의 변화와 영양염류의 동태를 조사하였다. 분해 69개월경과 후 신갈나무와 소나무 낙엽의 잔존률은 각각 $35.4{\pm}2.3%$와 $16.1{\pm}1.3%$로 소나무 낙엽의 분해가 신갈나무 낙엽의 분해보다 빠르게 진행되는 것으로 나타났다. 분해 69개월경과 후 신갈나무 낙엽과 소나무 낙엽의 분해상수(k)는 각각 5.97과 10.50으로 소나무 낙엽의 분해상수가 높게 나타났다. 신갈나무 낙엽의 분해과정에 따른 C/N, C/P 비율은 초기에 각각 43.1, 543.9이었으나 69개월경과 후에는 각각 8.7과 141.2로 점차 감소하였으며, 소나무 낙엽의 경우 초기 C/N, C/P 비율은 각각 151.2와 391.4로 나타났고, 분해 69개월경과 후에는 각각 22.9와 136.5로 나타났다. 낙엽의 초기 N, P, K, Ca, Mg의 함량은 신갈나무 낙엽에서 각각 9.30, 0.23, 2.36, 3.14, 1.11mg/g, 소나무 낙엽에서 각각 3.02, 0.09, 1.00, 3.84, 0.62mg/g으로 신갈나무 낙엽에서 질소와 인의 함량이 현저히 높았다. 분해 69개월경과 후 N, P, K, Ca, Mg의 잔존률은 신갈나무 낙엽에서 각각 73.8, 60.9, 17.2, 20.3, 35.1%, 소나무 낙엽에서 각각 69.5, 75.3, 12.3, 10.9, 10.8%로 나타났다.

• 정보처리학회논문지C
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• 제12C권5호
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• pp.665-672
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• 2005

본 논문에서는 웨이블릿 변환과 보간법을 이용하여 OFDM(Orthogonal Frequency Division Multiplexing)시스템을 위한 새로운 파일럿 지원 채널 추정 기법을 소개한다. 웨이블릿 변환의 AWGN(Additive White Gaussian Noise) 감쇄능력이 뛰어남으로 인해 파일럿 채널은 아주 정확하게 추정될 수 있고, 이렇게 추정된 파일럿 데이터는 남아있는 다른 데이터 심볼 채널에 대해 2차 다항식 보간법을 하는데 사용된다. Short WATM(Wireless Asynchronous Transfer Mode)채널에 대한 모의실험 결과를 통해, 이 추정기를 쓴 OFDM 시스템의 성능은 완벽한 CSI(Channel State Information)에서 발생하는 BER(Bit Error Ratio) 성능과 거의 비슷한 것을 확인할 수 있다.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2008년도 춘계학술대회논문집
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• pp.393-396
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• 2008

Propellant consumption control for space launch vehicle can be achieved by propellant utilization system (PUS) and tank depletion system (TDS). In the course of developing new space launch vehicles, the main target of design is on reducing of space launch vehicle weight, which results in increasing both specific impulse and payload weight. The weights of space launch vehicles are generally allocated to structure, propulsion system, and propellants loaded. The quantity of propellants filled in propellant tanks may be estimated with the propellants actually consumed by propulsion system to complete its mission and the propellants left on-board at the time of engine shut-off. To minimize the remaining quantity of propellants on-board the supplying propellants' O/F ratio should be controlled from the certain time before engine shutdown. To control an O/F ratio, a control system, which accurately measures and compares the remainder of propellants in tanks and pipes, should be needed. This paper solely dedicates its contents to explore the merits and demerits of various level sensor, which is one of the important elements for PUS and TDS, and the transmission and control of signals within space launch vehicle.

• The Journal of Korean Physical Therapy
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• 제27권6호
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• pp.419-424
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• 2015

Purpose: This study aimed to evaluate the effects of lumbar stabilization exercise on the abdominal muscle-back muscle ratio in white-collar workers. Methods: Forty white-collar workers without any pain who worked at an information technology (IT) company located in the Gyeonggi province were included in this study. Of these, 20 subjects were randomly allocated to the lumbar stabilization exercise group, whereas the remaining 20 were randomly allocated to the control group. The lumbar stabilization exercise group performed a 40-minute-long exercise once a week for 8 weeks. The strength of the abdominal and back muscles was measured using the CENTAUR 3-D Spatial Rotation Device (BFMC, Germany). Data analysis was conducted using SPSS 18.0 for Windows. The Paired t-test was performed to compare the values measured before and after exercise within each group. The independent sample t-test was performed to analyze the differences between the 2 groups. The statistical significance for all the analyses was set at .05. Results: The strength of the abdominal muscles after the exercise significantly differed between the lumbar stabilization exercise group and the control group (p<0.05). However, the increase in the abdominal muscle-back muscle ratio was significant in only the lumbar stabilization exercise group (p<0.05), but not in the control group (p>0.05). Conclusion: The improvement of the abdominal muscle-back muscle ratio through lumbar stabilization exercise may have positive effects on lumbar stabilization. Moreover, lumbar stabilization exercise is considered beneficial for the prevention of back pain and musculoskeletal diseases.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2004년도 Asia Display / IMID 04
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• pp.26-29
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• 2004

S-PVA is a new technology which enables screen quality advantages over S-IPS and MVA, including high transmittance, >1000:1 contrast ratio, sub-10ms response time, and wide angle of view with no off-axis image inversion and undetectable gamma distortion. This new technology will be described in detail. This paper also addresses the other remaining performance issues facing LCD-TV, including Samsung's plans for addressing these challenges. For example, until recently, inter-gray response time and associated motion blur were significant issues for achieving LCD-TV images quality. Samsung has invented DCC-II technology to achieve sub-10ms response time, and this achievement is described herein. Other technology advancements, including next-generation color performance and ultra-low black performance and improvement of off axis image quality are also discussed in this paper.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2000년도 제1회 학술대회 논문집
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• pp.223-224
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• 2000

As technology level of TFT-LCD advances, application to TV becomes an emerging important area for LCD makers. In this paper, we review current LCD technology level to be used in TV such as liquid crystal response behavior, color accuracy, contrast ratio, brightness and panel size. Based on the understanding of current limitations in LCD compared with CRT, the improvement plan to render 'near perfect motion picture' reproduction with LCD is proposed. Digital TV is a great opportunity for digital LCD panels, but we have to solve remaining technical and cost issue in order to be competitive with other large size TV technologies such as PDP, CRT or projection type. In preparing the upcoming digital TV era with advanced TFT-LCD, the hurdles and prospect of larger size LCD-TV panels will be discussed.

• 천문학논총
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• 제11권1호
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• pp.263-277
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• 1996

We have intensively carried out numerical calculations on flare predictions from the solar activity data for photospheric sunspots, chromospheric flare and plages, coronal X-ray intensities and 2800MHz radio fluxes, by using multilinear regression method. Intensities of solar flares for the next day have been predicted from the solar data between 1977-1982 and 1993-1996. Firstly, we have calculated flare predictions with the multilinear regression method, by using separate solar data in growth and decay phase of sunspot area and magnetic field strength from the whole data on solar activities. Secondly, the same operations as above have been made for the remaining data after removal of the data with large deviation from the mean calculated by the above prediction method. we have reached a conclusion that average hit ratio of correct predictions to total predictions of flares with class of M5 over has been as high as 70% for the first case and that of correct prediction number to total observation number has been shown as 61%.

• Steel and Composite Structures
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• 제29권1호
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• pp.23-37
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• 2018

In this paper, seismic provisions related to built-up special concentrically braced frames (BSCBFs) are investigated under cyclic loading using non-linear finite element analysis of a single-bay single-story frame. These braces, which contain double angle and double channel brace sections, are considered in two types of single diagonal and X-braced frames. The results of this study show that current seismic provisions such as observing the 0.4 ratio for slenderness ratio of individual elements between stitch connectors are conservative in BSCBFs, and can be increased according to the type of braces. Furthermore, such increments will lead to decreasing or remaining the current middle protected zone requirements of each BSCBFs. Failure results of BSCBFs, which are related to the plastic equivalent strain growth of members and ductility capacity of the models, show that the behaviors of double channel back-to-back diagonal braces are more desirable than those of similar face-to-face ones. Also, for double angle diagonal braces, results show that the failure of back-to-back BSCBFs occurs faster in comparison with face-to-face similar braces. In X-braced frames, cyclic and failure behaviors of built-up face-to-face models are more desirable than similar back-to-back braces in general.

• 한국염색가공학회지
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• 제31권3호
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• pp.177-186
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• 2019

In this study, we investigated for synthetic hydrotalcite in chloroprene rubber foam. Experiments were carried out to find the optimum content ratio by controlling the contents of MgO and Hydrotalcite. Swelling test in toluene immersion was made to measure the crosslinking density of CR foams, and the cure properties were investigated with flat die rheometer and Mooney viscosity. The difference of hardness, tensile strength and elongation at break were observed after immersing in 7% NaCl or 21% NaCl solutions for a day and four days. In addition, the volume change and water content remaining in CR foam were measured after immersing NaCl solution. As content of MgO increased, the value of the cure torque tended to increase, but it was almost constant above 2phr of MgO. However, the Mooney viscosity decreased with increasing MgO content. The crosslinking density, determined by the swelling ratio, showed that the CR compound without MgO showed a higher degree of swelling. When the content of hydrotalcite/MgO was 3:2, it was the lowest volume change of CR form. Also, As the content of hydrotalcite decreased, the difference of mechanical properties before and after immersion NaCl solution increased.