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.

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.

직렬 연결 위상 천이 장주기 격자의 특성과 초기 커플링 세기 효과에 관한 연구

김민성,한영근,Kim, Min-Sung,Han, Young-Geun 한국광학회 2006 한국광학회지 Vol.17 No.1

위상 천이 광섬유 격자를 직렬로 연결하였을 경우 파장 투과 특성에 대해서 이론 및 실험적으로 분석하였다. $\pi$만큼의 위상 천이가 유도된 장주기 격자의 파장 투과 특성은 직렬 연결되는 위상 천이 장주기 격자의 개수에 따라 변화하며 개수를 증가시킴에 따라 파장 투과 대역폭을 증가시킬 수 있다. 또한 $\pi$-위상 천이 장주기 격자의 파장 투과 대역폭은 격자 길이를 변화시킴에 따라 조절할 수 있으며 길이가 다른 두 개의 $\pi$-위상 천이 장주기 격자를 직렬로 연결하면 파장 투과 및 제거 대역폭을 조절할 수 있다 그리고 장주기 격자의 반을 UV에 노출 시켰을 때, 위상 천이 장주기 격자가 형성됨을 관찰하였고, 초기 커플링 세기에 따라 격자의 형성이 달라짐과 인가되는 인상 천이 크기에 따라서 다양한 형태의 위상 천이 장주기 광섬유 격자의 투과 특성을 나타내었다. The transmission characteristics of multiply cascaded phase-shifted long-period fiber gratings(LPFGs) were investigated theo-retically and experimentally. Their passband can be changed by increasing the number of p-shifted LPFGs. When two p-shifted LPFGs with different grating lengths are cascaded in series, the bandwidth of the rejection band and passband can be controlled by the pristine characteristics of two gratings. We also investigate the transmission characteristics of phase-shifted LPFG by exposing the half of LPFG region to UV laser. The transmission characteristics strongly depend on the initial coupling strength of the LPFG.

저잡음 · 고신뢰성 Differential Paired eFuse OTP 메모리 설계

김민성,김려연,학문초,하판봉,김영희,Kim, Min-Sung,Jin, Liyan,Hao, Wenchao,Ha, Pan-Bong,Kim, Young-Hee 한국정보통신학회 2013 한국정보통신학회논문지 Vol.17 No.10

본 논문에서는 power IC에서 파워가 ON되어있는 동안 입력 신호인 RD(Read) 신호 포트에 glitch와 같은 신호 잡음이 발생하더라도 파워-업(power-up)시 readout된 DOUT 데이터를 유지하면서 다시 읽기 모드로 재진입하지 못하도록 막아주는 IRD(Internal Read Data) 회로를 제안하였다. 그리고 pulsed WL(Word-Line) 구동방식을 사용하여 differential paird eFuse OTP 셀의 read 트랜지스터에 수 십 ${\mu}A$의 DC 전류가 흐르는 것을 방지하여 blowing 안된 eFuse 링크가 EM(Electro-Migration)에 의해 blowing되는 것을 막아주어 신뢰성을 확보하였다. 또한 program-verify-read 모드에서 프로그램된 eFuse 저항의 변동을 고려하여 가변 풀-업 부하(variable pull-up load)를 갖는 센싱 마진 테스트 기능을 수행하는 동시에 프로그램 데이터와 read 데이터를 비교하여 PFb(pass fail bar) 핀으로 비교 결과를 출력하는 회로를 설계하였다. $0.18{\mu}m$ 공정을 이용하여 설계된 8-비트 eFuse OTP IP의 레이아웃 면적은 $189.625{\mu}m{\times}138.850{\mu}m(=0.0263mm^2)$이다. In this paper, an IRD (internal read data) circuit preventing the reentry into the read mode while keeping the read-out DOUT datum at power-up even if noise such as glitches occurs at signal ports such as an input signal port RD (read) when a power IC is on, is proposed. Also, a pulsed WL (word line) driving method is used to prevent a DC current of several tens of micro amperes from flowing into the read transistor of a differential paired eFuse OTP cell. Thus, reliability is secured by preventing non-blown eFuse links from being blown by the EM (electro-migration). Furthermore, a compared output between a programmed datum and a read-out datum is outputted to the PFb (pass fail bar) pin while performing a sensing margin test with a variable pull-up load in consideration of resistance variation of a programmed eFuse in the program-verify-read mode. The layout size of the 8-bit eFuse OTP IP with a $0.18{\mu}m$ process is $189.625{\mu}m{\times}138.850{\mu}m(=0.0263mm^2)$.

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.

실험적 골 병소에 대한 콘빔형전산화단층영상과 초음파영상의 비교

김민성,박철우,김규태,최용석,황의환,Kim, Min-Sung,Park, Cheol-Woo,Kim, Gyu-Tae,Choi, Yong-Suk,Hwang, Eui-Hwan 대한영상치의학회 2010 Imaging Science in Dentistry Vol.40 No.3

Purpose : This study was performed to evaluate the diagnostic ability of ultrasonography in detection of bone defects and new bone formation. Materials and Methods : Experimental bony defects were prepared on the parietal bone samples acquired from 3.5 kg New Zealand male rabbits. The defects were evaluated using ultrasonography and CBCT, and examined histologically at interval of 1, 3, 6, and 8 weeks. Results : Ultrasonograph demonstrated hyperechogenicity in the defect area at 3 weeks and broadened hyperechogenicity from the margin of bone defect at 6 and 8 weeks due to new bone formation. On the CBCT images, new bone formation was first observed at 3 weeks around the margin of the defect, and showed gradually increase at 6 and 8 weeks. Histologic findings revealed existence of the fibroblasts and fibrous connective tissue with abundant capillary vessels only at 1 week, but osteoid tissue and newly formed trabecular bone at 3 weeks. Bone remodeling in the defect area was observed at 6 weeks and increased calcification and dense trabecular bone formation was observed at 8 weeks. Conclusions : Ultrasonograph proved to be a very useful diagnostic tool in detecting the bony defect and new bone formation. Additionally, ultrasonography provided valuable information regarding the blood supply around the defect area.

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.

열린타원구멍을 통한 기이색전증이 발병 원인으로 추정되는 뇌경색 환자의 동서 협진 치험 1례

김민성,옥효준,양지연,정택수,선종주,유소정,Kim, Min-sung,Ok, Hyo-joon,Yang, Jee-yun,Jeong, Taek-su,Sun, Jong-joo,You, So-jung 대한한방내과학회 2016 大韓韓方內科學會誌 Vol.37 No.5

Objective: To evaluate the effects of integrative treatment with conventional and Korean medicine on cerebral infarction due to presumed paradoxical embolism through a patent foramen ovale. Methods: We applied acupuncture, herbal medication, western medication, and physical therapy routinely every day and applied fluid therapy provided as needed. The NIHSS, K-MBI, MRS, MMT, and MMSE-K score were determined to assess any improvement in symptoms. Results: Scores appeared to be improved for the NIHSS (9 to 5), K-MBI (94 to 100), MRS (2 to 1), MMT (2+, 4 to 4, 4), MMSE-K (24 to 26). No side effects were observed during the treatment. Conclusions: This study demonstrates that integrative treatment with conventional and Korean medicine may be an effective option for treating cerebral infarction due to a presumed paradoxical embolism through a patent foramen ovale.

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%.

스폰지 복제법을 이용한 Ag 코팅 BCP 지지체의 제조 및 평가

김민성,김영희,송호연,민영기,이병택,Kim, Min-Sung,Kim, Young-Hee,Song, Ho-Yeon,Min, Young-Ki,Lee, Byong-Taek 한국재료학회 2010 한국재료학회지 Vol.20 No.8

As a starting material, BCP (biphasic calcium phosphate) nano powder was synthesized by a hydrothermal microwave-assisted process. A highly porous BCP scaffold was fabricated by the sponge replica method using 60 ppi (pore per inch) of polyurethane sponge. The BCP scaffold had interconnected pores ranging from $100\;{\mu}m$ to $1000\;{\mu}m$, which were similar to natural cancellous bone. To realize the antibacterial property, a microwave-assisted nano Ag spot coating process was used. The morphology and distribution of nano Ag particles were different depending on the coating conditions, such as concentration of the $AgNO_3$ solution, microwave irradiation times, etc. With an increased microwave irradiation time, the amount of coated nano Ag particles increased. The surface of the BCP scaffold was totally covered with nano Ag particles homogeneously at 20 seconds of microwave irradiation time when 0.6 g of $AgNO_3$ was used. With an increased amount of $AgNO_3$ and irradiation time, the size of the coated particles increased. Antibacterial activities of the solution extracted from the Ag-coated BCP scaffold were examined against gram-negative (Escherichia coli) and gram-positive bacteria (Staphylococcus aureus). When 0.6 g of $AgNO_3$ was used for coating the Ag-coated scaffold, it showed higher antibacterial activities than that of the Ag-coated scaffold using 0.8 g of $AgNO_3$.