합성고분자첨가제의 난류마찰저항 감소효과 연구

김남수,김종보,김인석,최형진,Kim, N.S.,Kim, C.B.,Kim, I.S.,Choi, H.J. 대한설비공학회 1993 설비공학 논문집 Vol.5 No.3

Experimental investigations have been carried out to find the effect of drag reduction caused by effective polymer additives in turbulent flows. The experiments were undertaken with a test section of 9.8mm pipe diameter and 3500 mm pipe length(L/D=357) in a closed loop, and Copolymer-X and Polyacrylamide(PAAM) were used as polymer additives for comparisons. The tests were carried out under different polymer concentrations, and the temperatures of the flow considered were $26^{\circ}C$, $60^{\circ}C$ at the flow velocity of 5.3 m/s. The rate of drag reduction obtained by Copolymer-X is found to be considerably higher than that of PAAM in turbulent flows. Copolymer-X is also found to be very reliable for mechanical degradation, which has not been the case in any other additives. It is concluded that Copolymer-X is considered to be one of the most effective agents as an additive especially for long time hydraulic transports. It is also found that polymer degradation in more likely at lower polymer concentrations in the turbulent flows.

Dual Gate Emitter Switched Thyristor의 전기적 특성

김남수,이응래,최지원,김영석,김경원,주변권,Kim, Nam-Soo,Lee, Eung-Rae,Cui, Zhi-Yuan,Kim, Yeong-Seuk,Kim, Kyoung-Won,Ju, Byeong-Kwon 한국전기전자재료학회 2005 전기전자재료학회논문지 Vol.18 No.5

Two dimensional MEDICI simulator is used to study the electrical characteristics of Dual Gate Emitter Switched Thyristor. The simulation is done in terms of the current-voltage characteristics with the variations of p-base impurity concentrations and current flow. Compared with the other power devices such as MOS Controlled Cascade Thyristor(MCCT), Conventional Emitter Switched Thyristor(C-EST) and Dual Channel Emitter Switched Thyristor(DC-EST), Dual Gate Emitter Switched Thyristor(DG-EST) shows to have tile better electrical characteristics, which is the high latch-up current density and low forward voltage-drop. The proposed DG-EST which has a non-planer u-base structure under the floating N+ emitter indicates to have the better characteristics of latch-up current and breakover voltage in spite of the same turn-off characteristics.

우리나라와 세계의 SPF 돼지 보급실태 및 향후전망

김남수,Kim, Nam-Su 대한양돈협회 1989 養豚 Vol.11 No.2

Cordierite 의 기공 특성 연구

김남수,이두찬,양진 ( Nam Soo Kim,Doo Chan Lee,Jin Yang ) 한국화학공학회 1996 화학공학의이론과응용 Vol.2 No.2

Electrical Characteristics of CMOS Circuit Due toChannel Region Parameters in LDMOSFET

김남수,이형규,Zhi-Yuan Cui,Kyoung-Won Kim 한국전기전자재료학회 2006 Transactions on Electrical and Electronic Material Vol.7 No.3

The electrical characteristics of CMOS inverter with LDMOSFET are studied for high power and digital circuit application by using two dimensional MEDICI simulator. The simulation is done in terms of voltage transfer characteristic and on-off switching properties of CMOS inverter with variation of channel length and channel doping levels. The channel which surrounds a junction-type source in LDMOSFET is considered to be an important parameter to decide a circuit operation of CMOS inverter. The digital logic levels of input voltage show to increase with increase of n-channel length and doping levels while the logic output levels show to the almost constant.

양자점 표지 형광미세비드의 합성 및 응용

김남수,Kim, Nam-Soo 한국식품연구원 2009 食品技術 Vol.22 No.3

성내천 복원 후 지역주민의 커뮤니티 의식에 대한 연구

김남수,이인환,김용근,Kim, Nam-Su,Lee, In-Hwan,Kim, Yong-Geun 한국조경학회 2011 韓國造景學會誌 Vol.39 No.4

도시하천은 산업혁명 이후 산업화 도시화가 진행되면서 무분별하게 복개 개발되어 지역주민들의 일상적 삶의 공간에서 멀어졌다. 최근 도시하천 복원사업이 진행되면서 접근성이 개선되고 쾌적한 환경으로 변모하여 사람들의 유입과 이용이 크게 늘면서 복원된 하천 주변 지역주민들의 커뮤니티 의식에 일정부분 영향을 미치고 있는 것으로 보인다. 본 연구는 도시하천의 복원이 지역주민들의 커뮤니티 의식에 어떠한 영향을 미치는지 규명하고자 수행되었으며, 이를 위해 최근 복원된 서울시 송파구 성내천을 방문한 방문객을 대상으로 설문조사를 시행하였다. 설문분석의 인자는 크게 성내천의 이용현황, 커뮤니티 의식(소속감, 연대의식, 정주의식), 복원사업 전후 비교(커뮤니티 의식변화, 지역효과 변화)등의 항목으로 구성되었다. 분석결과에 따르면 성내천 복원사업 후 일주일에 1~2회 이상 이용하는 방문객이 가장 많았다. 이들의 주된 방문목적은 '휴식 및 운동'이었고, '이웃이나 타인을 만나는 장소'로 이용하는 비율은 낮게 나타났으며, 성내천을 이용하는 주민들의 커뮤니티 의식은 대체로 높은 수준이었다. 방문빈도에 따라 세 집단으로 나누어 집단 간 커뮤니티 의식 차이를 분석한 결과, 집단 간 커뮤니티 의식 수준에 유의한 차이가 있었고, 특히 방문횟수가 많은 집단에서 커뮤니티 의식 수준이 높게 나타났다. 이 같은 결과로 볼 때 복원된 도시하천이 지역주민들의 적극적인 이용과 커뮤니티 활동을 활성화함으로써 지역에 대한 커뮤니티 의식을 고취하기 위해서는 주민들이 이용할 수 있는 적절한 시설과 프로그램 제공이 중요하다고 판단된다. During the industrialization and urbanization of the country, urban rivers have been covered over and developed without forethought and thus became estranged from spaces utilized by area residents in everyday life. Recently, an influx of people and uses have increased largely because accessibility improved through restoration projects which have transformed these river areas into pleasant environments. It thus appears that these projects have an impact on community consciousness for area residents who live near the restored rivers to some extent. The purpose of this study was to determine via questionnaire the effects and influences of urban river restoration on area residents targeting visitors to Seongnaecheon(stream), Songpa-gu, Seoul, which has been restored recently. Factors in the questionnaire analysis included such items as the use status of Seongnaecheon, community consciousness(feeling of belonging, solidarity, feeling settled), and a before and after comparison of the restoration(change of consciousness, regional effects), etc. According to the results of analysis, visitors who have utilized the stream more than 1~2 times per week after the restoration project accounted for the greatest portion. The main purposes of these visits were to 'rest' and 'exercise' while the ratio of using it as a 'meeting space with neighbors and strangers' was low. Community consciousness of area residents using Seongnaecheon was generally high. As a result of an analysis of consciousness differences between groups after dividing visitors into 3 groups according to the frequency of visits, there were significant differences in the consciousness level between groups with high community consciousness levels in visitors who visited frequently. In consideration of these results, the provision of programs along with proper facilities that can be used is deemed important for area residents so as to inspire community consciousness of the area by means of activating both community activities and the progressive use of the restored river.

UMM(Unitary Matrix Modulation)을 이용한 LDPC(Low Density Parity Check) 코디드 OFDM 시스템

김남수,강환만,조성호,Kim Nam Soo,Kang Hwan Min,Cho Sung Ho 한국통신학회 2005 韓國通信學會論文誌 Vol.30 No.5a

다중 안테나 시스템에서 UMM (unitary matrix modulation)을 사용한 방법을 USTM (unitary space-time modulation)이라 부른다. OFDM 시스템에서 coherence bandwidth 만큼의 이격을 두고 UMM의 대각 행렬을 이용한 방법이 제안되고 있다. 또한 최근에 디코딩 방법이 간단하고 좋은 성능을 갖는 LDPC (low density parity check) 코드에 대한 연구가 진행되고 있다. 본 논문에서 UMM (unitary matrix modulation)을 사용하고 LDPC 코디드 된 OFDM 시스템을 제안한다. 또한 다중 송신 안테나를 사용하여 송신 diversity 이득을 얻는 것이 아니라, 하나의 송신 안테나를 이용하여 채널의 coherence bandwidth 만큼의 주파수 간격 (splitting)을 두어 채널에 대한 주파수 이득을 고려하여 UMM/OFDM 시스템을 설계 하였다. 이 방법을 이용하여 본 논문에서 제안된 UMM-S/OFDM에 대한 성능 특성을 다중 경로 Rayleigh 페이딩 채널 환경에서 시뮬레이션을 통하여 검증하였다. Unitary matrix modulation (UMM) is investigated in multiple antennas system that is called unitary space-time modulation (USTM). In an OFDM, the diagonal components of UMM with splitting over the coherence bandwidth (UMM-S/OFDM) have been proposed. Recently LDPC code is strongly attended and studied due to simple decoding property with good error correction property. In this paper, we propose LDPC coded UMM-S/OFDM for increasing the system performance. Our proposed system can obtain frequency diversity using UMM-S/OFDM like USTM/OFDM, and large coding gain using LDPC code. The superior characteristics of the proposed UMM-S/OFDM are demonstrated by extensive computer simulations in multi-path Rayleigh fading channel.

구약감자 Glucomannan의 이화학적 특성

김남수,지수경,목철균,김승호,Kim, Nam-Soo,Ji, Soo-Kyung,Mok, Chul-Kyoon,Kim, Seung-Ho 한국식품과학회 1994 한국식품과학회지 Vol.26 No.6

구약감자(Amorphophallus konjac)로부터 glucomannan을 제조하고 그 이화학적 특성을 구명하였다. 예비정제 구약감자분말로부터 ethanol 침전법에 의하여 정제 glucomannan을 제조하였으며 이때의 수율은 67.2%였다. 구약감자 glucomannan에 대하여 일반성분, 총식이섬유, 미네랄 분석을 행하였다. Isopropanol : $H_2O$(4 : 1, v/v)을 전개용매로 하여 TLC 분석을 행하였을 때 mannose와 glucose가 성분당으로 확인되었으며 Protein Pak 300SW column을 사용하여 HPLC 분석시 분자질량은 240에서 370 kDa 범위내에 있었다. 구약감자 glucomannan의 수분결합력은 guarr와 xanthan 검을 제외한 다른 검틀의 경우보다 높았으며 bovine serum albumin 존재시의 거품생성능은 $8.60{\sim}9.45\;ml$로서 단백질 자체의 경우보다 높았고 다른 검들의 경우보다도 높았다. 구약감자 glucomannan 농도틀 2%까지 중가시켜 가며 팽윤특성을 보았을 때 최대점도는 농도외 중가에 따라 현저하게 중가한반면 최대점도에 이르는 팽윤시간은 점차 감소함을 알수 있었다. 일정농도에서 온도를 높이면 최대점도와 최대점도에 이르는 팽윤시간이 동시에 감소하였다. A 0.625% dispersion of the pretreated konjac (Amorphophallus konjac) flour was treated with 3 volumes of ethanol and the precipitate was dried at room temperature to produce purified glucomannan in 67.2% yield. Konjac glucomannan was analyzed for proximate composition and the contents of total dietary fiber and minerals. TLC analysis with a mobile phase of isopropanol : $H_2O$(4 : 1, v/v) revealed the presence of mannose and glucose as component sugars. The molecular mass of konjac glucomannan was in the range between 240 and 370 kDa as determined by HPLC with a Protein Pak 300SW column. Water holding capacity of konjac glucomannan was greater than those of most other gums except guar and xanthan gums. Konjac glucomannan accelerated foam formation of bovine serum albumin. As the concentration of konjac glucomannan increased up to 2%, maximum viscosity increased drastically, whereas the swelling time at maximum viscosity decreased. When swelling temperature increased, maximum viscosity and the swelling time at maximum viscosity decreased simultaneously.

점진적 최적화 기법에서 불규칙 삼각망을 이용한 평면구조의 응력경로 탐색모델의 개발

김남수,이정재,윤성수,김윤순,Kim, Nam-Su,Lee, Jeong-Jae,Yoon, Seong-Soo,Kim, Yoon-Soon 한국농공학회 2004 한국농공학회논문집 Vol.46 No.4

Stress Path Search Model of Evolutionary Structural Successive Optimization (SPSMESO) using Triangular Irregular Network(TIN) was developed for improving over burden at initial design of ESO and strict stress direction of strut-and-tie model and truss model. TIN was applied for discretizing structures in flexible stress path and segments of TIN was analyzed as one-dimensional line element for calculating stress. Finally, stress path was searched using ESO algorithm. SPSMESO was efficient to express the direction of stress for 2D structure and time saving.