윈드프로파일러 자료를 이용한 연안 지역 국지 바람장 모의

김민성,김광호,김박사,강동환,권병혁,Kim, Min-Seong,Kim, Kwang-Ho,Kim, Park-Sa,Kang, Dong-Hwan,Kwon, Byung Hyuk 해양환경안전학회 2016 海洋環境安全學會誌 Vol.22 No.2

본 연구에서는 3차원 바람장 생성을 위한 수치 모델의 상층기상 입력 자료로 윈드프로파일러 자료의 적용 가능성과 유용성을 조사했다. 10개 지점의 윈드프로파일러 자료와 기상 예측 모델 WRF의 결과를 기상진단 모델 CALMET에 입력하여 산출한 바람장을 8개 지역에서 관측된 라디오존데 자료와 통계적으로 비교 검증하였다. WRF 바람장 모의 결과를 CALMET에 적용하여 모의한 수평 풍속에 비해 1시간 간격의 윈드프로파일러 자료를 CALMET에 적용하여 모의한 수평 풍속이 평균 제곱근 오차 1.5 m/s 내에서 관측 결과와 일치하고 특히 연안 지역에서 해풍과 같은 국지적인 바람 변화를 잘 모의하였다. 풍향의 평균 제곱근 오차는 $50^{\circ}{\sim}70^{\circ}$로써 지형의 영향으로 오염된 윈드프로파일러의 풍향 오차에 기인한다. 윈드프로파일러 자료를 CALMET에 적용하면 대부분의 고도에서 상대적으로 정확한 바람을 신속하고 정확하게 모의할 수 있기 때문에 본 연구에서 제시하는 방법은 연안 지역의 기상뿐만 아니라 안전 환경 감시에 유용할 것으로 기대된다. In this paper, the applicability and usefulness of windprofiler input data were investigated to generate three dimensional wind field. A logical diagnostic model CALMET with windprofiler data at ten sites and with weather forecasting model WRF output was evaluated by statistically comparing with the radiosonde data at eight sites. The horizontal wind speed from CALMET simulated with hourly windprofiler data is in good agreement with radiosonde observations within 1.5 m/s of the root mean square error, especially local circulation of wind such as sea breeze over the coastal region. The root mean square error of wind direction ranged $50^{\circ}{\sim}70^{\circ}$ is due to the wind direction error from the windprofiler polluted by ground clutters. Since the exact wind can be produced quickly and accurately in most of the altitude with windprofiler data on CALMET, we expect the method presented in this study to be useful for the monitoring of safe environment as well as weather in the coastal zone.

오스테나이트계 스테인레스강(STS304) 앵글 볼트 접합부의 구조적 거동에 관한 실험적 연구

김민성,김태수,김승훈,이용택,Kim, Min-Seong,Kim, Tae-Soo,Kim, Seung-Hun,Lee, Yong-Taeg 한국강구조학회 2011 韓國鋼構造學會 論文集 Vol.23 No.1

강구조물에서 접합부의 구조적 거동을 파악하기 위해서 국내외에서 많은 이론과 실험을 통한 연구가 진행되고 있다. 특히, 국내에서는 탄소강 ㄱ형강의 블록전단파단과 전단지체현상 등에 대한 연구가 수행되어 왔다. 본 연구에서는 오스테나이트계 스테인레스강 앵글의 하중방향의 연단거리와 볼트배열(1행 1열,1행 2열)을 주요변수로 실험체를 계획하여, 앵글 볼트 접합부의 파단형태와 면외변형의 영향을 조사한다. 또한, 현행 기준식에 의한 예측결과와 실험결과의 파단양상과 최대내력을 비교하고 면외변형으로 인한 내력저하정도를 평가한다. With regard to steel construction, many studies have been performed to examine the structural behavior of the bolted connections domestically and in other countries. Especially, a domestic study was conducted on the block shear fracture and shear lag effect on the single-bolted angle connection in carbon steel. In this study, specimens were prepared with the end distance parallel to the loading direction and bolt arrangement ($1{\times}1$, $1{\times}2$), as the main variables. Then the fracture mode and the curling effect on the bolted angle connection in austenitic stainless steel were investigated. Moreover, the fracture mode and ultimate strength were compared, and the strength reduction by curling was estimated.

Al-Zn 혼합물의 열 증발을 이용한 ZnO 결정의 합성에서 결정의 형상에 미치는 합성 온도와 시간의 영향

김민성,Kim, Min-Sung 한국재료학회 2015 한국재료학회지 Vol.25 No.6

ZnO micro/nanocrystals at large scale were synthesized through the thermal evaporation of Al-Zn mixtures under air atmosphere. The effect of synthetic temperature and time on the morphology of the micro/nanocrystals was examined. It was found that the temperature and time affected the morphology of the ZnO crystals. At temperatures below $900^{\circ}C$, no crystals were synthesized. At a temperature of $1000^{\circ}C$, ZnO crystals with a rod shape were synthesized. With an increase in temperature from $1000^{\circ}C$ to $1100^{\circ}C$, the morphology of the crystals changed from rod shape to wire and granular shapes. As the time increased from 2 h to 3 h at $1000^{\circ}C$, tetrapod-shaped ZnO crystals started to form. XRD patterns showed that the ZnO crystals had a hexagonal wurtzite structure. EDX analysis revealed that the ZnO crystals had high purity. It is believed that the ZnO nanowires were grown via a vapor-solid mechanism because no catalyst particles were observed at the tips of the micro/nanocrystals in the SEM images.

플래시를 이용한 웹기반 수업에 관한 고찰

김민성,박성훈,Kim, Min-Sung,Park, Sung-Hoon 한국디지털콘텐츠학회 2010 한국디지털콘텐츠학회논문지 Vol.11 No.2

웹기반 교육은 학습자 중심의 학습과 협동학습을 촉진시킬 수 있는 새로운 수업도구로서 기존의 획일화된 교수-학습 방식에서 탈피하여 새로운 교수모형에 대한 연구로 발전되고 있다. 강력한 웹 저작도구중 하나인 플래시를 사용하면 컴퓨터 그래픽, 애니메이션과 사운드 그리고 동영상 등의 활용으로 학습의 효과를 극대화 시킬 수 있다. 본 논문에서는 플래시를 사용한 교육 자료의 개발 및 배포와 효율적인 웹기반 수업에 대하여 고찰하고자 한다. Web-based instruction is being developed as a new study model getting out of the traditional standardized education method. It is a new education tool which promotes learner-centered and cooperative study. Flash, as one of the most powerful web authoring tool can maximize the effectiveness of learning using computer graphic, animation, sounds and video. In this paper, we will look at developing and distributing education materials using flash and the efficient web-based instructions.

어장환경 - 활짝 웃는 바다가 좋다

김민성,Kim, Min-Seong 한국어촌어항협회 2011 어항어장 Vol.96 No.-

채널보상기법을 사용한 전화 음성 연속숫자음의 인식 성능향상

김민성,정성윤,손종목,배건성,Kim Min Sung,Jung Sung Yun,Son Jong Mok,Bae Keun Sung 대한음성학회 2002 말소리 Vol.44 No.-

Channel distortion degrades the performance of speech recognizer in telephone environment. It mainly results from the bandwidth limitation and variation of transmission channel. Variation of channel characteristics is usually represented as baseline shift in the cepstrum domain. Thus undesirable effect of the channel variation can be removed by subtracting the mean from the cepstrum. In this paper, to improve the recognition performance of Korea connected digit telephone speech, channel compensation methods such as CMN (Cepstral Mean Normalization), RTCN (Real Time Cepatral Normalization), MCMN (Modified CMN) and MRTCN (Modified RTCN) are applied to the static MFCC. Both MCMN and MRTCN are obtained from the CMN and RTCN, respectively, using variance normalization in the cepstrum domain. Using HTK v3.1 system, recognition experiments are performed for Korean connected digit telephone speech database released by SITEC (Speech Information Technology & Industry Promotion Center). Experiments have shown that MRTCN gives the best result with recognition rate of 90.11% for connected digit. This corresponds to the performance improvement over MFCC alone by 1.72%, i.e, error reduction rate of 14.82%.

Evaluation of bubble suspension behavior in electrolyte melts

김민성,Kangwook Kim,Munkyeong Hwang,김규보,송주헌 한국화학공학회 2014 Korean Journal of Chemical Engineering Vol.31 No.2

The viscosity of a molten electrolyte mixture commonly used in direct coal fuel cells (DCFCs) was evaluated. The measurements were obtained from near the melting temperature to a high temperature at which a considerablybubbly flow was induced by decomposition. A gravity-driven capillary viscometer was employed to obtain the viscositydata under low Reynolds flow conditions, using a modified Poiseuille flow relationship. The importance of carbondioxide addition in measuring the intrinsic viscosity was clearly observed. In addition, the effect of the bubble suspensionon the viscosity was quantified in terms of the volume fraction and capillary number. The results showed that the increasein viscosity was best explained only by the difference in the volume fraction of spherical bubbles in the electrolytemelt.

pH 나노센서로의 응용을 위한 UV-가교 P4VP 박막에 고정한 금 나노입자의 특성

김민성,정연태,Kim, Min-Sung,Jeong, Yeon-Tae 한국전기전자재료학회 2008 전기전자재료학회논문지 Vol.21 No.11

In this report, we describe the use of gold nanoparticles (AuNPs) immobilized on pH. responsive, cross-linked poly(4-vinylpyridine) (P4VP) thin films, as a potential application for pH nanosensors. The methodology is based on the variation in surface plasmon resonance of immobilized AuNPs with changing the interparticle distances, caused by the swelling/deswelling of the pH responsive P4VP polymer films. The change in optical properties of the immobilized AuNPs in response to the pH of surrounding media was investigated by a simple yet powerful tool; UV-vis absorption spectroscopy. The swelling of the P4VP chains at pH 2 causes an increase in the interparticle distances of immobilized AUNPS ($\sim20nm$) and hence leads to a blue shift of 48 nm in their surface plasmon resonance band peak. On the other hand, when the surrounding media was altered from pH 2 to 10, a red shift of absorption maxima was observed. The changes were rapid, and the effect was reversible. This system could prove to be useful in fabricating nanosensors for detecting the pH or pH changes of surrounding aqueous medium.

표준 단일모드 광섬유와 EDFA를 이용한 10 Gb/s 40 파장다중 채널 신호의 3000 km 전송에서 분산 보상 맵 최적화와 분산 기울기 불일치 영향

김민성,최보훈,Kim Min-Sung,Choi Bo-Hun 한국통신학회 2005 韓國通信學會論文誌 Vol.30 No.1a

표준 단일모드 광섬유를 전송선으로 사용하고, Raman 증폭기 없이 EDFA 증폭기만을 사용하여, 각 채널당 10 Gb/s의 파장다중화된 40개 채널신호들을 장거리 전송하는 경제적인 광 링크를 구성한 뒤, 이 링크의 전송 성능 최적화를 위해 분산 맵 구조의 차이에 따른 성능 차이를 분석하였다. 이 링크의 분산 맵은 전치분산보상, 구간분산보상 그리고 후치분산보상으로 나누어지는데 이들의 다양한 조합을 통해 15 가지의 다양한 분산 맵들을 구성한 뒤 각각의 경우를 분석하여 링크 성능을 크게 향상시키는 최적화된 분산맵 구조를 구하였다. 또한, 이 최적화된 분산 조건이, 단일모드 광섬유와 분산보상 광섬유가 가지는 파장에 따른 분산 기울기의 불일치로 인해 받게 되는 영향을 조사하였고, 이 영향이 링크의 성능에 미치는 효과가 무시될 수 있는 분산 기울기의 허용 가능한 불일치 범위를 구했다. We have studied the dispersion properties of a 40 channel x 10 Gbit/s wavelength division multiplexer(WDM) transmission link using standard single mode fiber with all EDFA amplification over 30 x 100 km spans. The dispersion map of the link was investigated by adding fiber sections with positive or negative dispersion at the transmitter, within each amplifier span, and at the receiver. Optimum combinations of these dispersive fiber lengths were attained to significantly enhance the overall transmission performance.

한국어 연속 숫자음 전화 음성 인식에서의 오인식 유형 분석

김민성,정성윤,손종목,배건성,김상훈,Kim Min Sung,Jung Sung Yun,Son Jong Mok,Bae Keun Sung,Kim Sang Hun 대한음성학회 2003 말소리 Vol.46 No.-

Channel distortion and coarticulation effect in the Korean connected digit telephone speech make it difficult to achieve high performance of connected digit recognition in the telephone environment. In this paper, as a basic research to improve the recognition performance of Korean connected digit telephone speech, recognition error patterns are investigated and analyzed. Korean connected digit telephone speech database released by SiTEC and HTK system are used for recognition experiments. Both DWFBA and MRTCN methods are used for feature extraction and channel compensation, respectively. Experimental results are discussed with our findings.