석재가공용 다이아몬드 톱의 제조 및 특성

이현우,전우용,이오연,설경원,Lee Hyun-Woo,Jeon Woo-yong,Lee Oh-yeon,Seol Kyeong-won 한국분말야금학회 2004 한국분말재료학회지 (KPMI) Vol.11 No.5

The purpose of the present study is to determine an optimum composition using cheaper powders keeping with high performance of hard rock cutting diamond saw blade. With 50Fe-20(Cu . Sn)-30Co specimen, a part of Co was replaced by Ni(5%, 10%, and 15%, respectively). These specimens were hot pressed and sintered for predetermined time at various temperature. Sintering is performed by two different methods of temperature controlled method and specimen dimension controlled method. In order to determine the property of the sintered diamond saw blade, 3 point bending tester, X-ray diffractometer, and SEM were used. As the Co in the bond alloy was replaced by Ni, the hardness of the specimen increased. Thus the 50Fe-20(CuㆍSn)-15Co-15Ni specimen showed the maximum hardness of 104(HRB). The results of 3 point bending test showed that flexure strength decreased along with increase in Ni content. This is attributed to the formation of intermetallic compound(Ni$_{x}$Sn) determined by X-ray diffraction. The fracture surface after 3 point bending test showed that diamond was fractured in the specimen containing 0%, 5%, and 10%Ni, and the fracture occurred at the interface between diamond and matrix in the specimen containing 15%Ni. The cutting ability test showed that the abrasive property was not changed in the specimen containing 0%, 5%, and 10%Ni. The optimum composition determined in this study is 50Fe-20(CuㆍSn)-20Co-10Ni.

영상처리기법을 이용한 CCT 시편 균열의 자동관측법에 관한 연구

이현우,문기태,오세종,정병우,Lee, Hyun-Woo,Mun, Gi-Tae,Oh, Se-Jong,Jeong, Byung-Woo 대한기계학회 1997 大韓機械學會論文集A Vol.21 No.3

In the analysis of fatigue crack propagation behavior, the crack length is one of the most important factors. In the test of crack propagation, compliance method is widely used to detect crack length. The measurement of surface crack length is not so easy with compliance method. In this study, the image processing technique was applied to measure the surface crack length. CCD(Charge-coupled device) camera was used to observe the crack image and the computer program to detect crack length from stored crack image was developed. CCT(Center Cracked Tension) specimen was used to compare the compliance method with the image processing technique. The crack length which detected by the image processing techniques was found to be well consistent with that from the optical measurement.

측창 및 온실 폭이 자연환기 성능에 미치는 영향

이현우,우영회,이종원,Hyun Woo Lee,Young Hoe Woo,Jong Won Lee 국립한국농수산대학교 교육개발센터 2023 현장농업연구지 = Journal of practical agricultural resear Vol.25 No.1

In summer, the natural ventilation performance for varying greenhouse width is very important in the glasshouses for year round cultivation. The effect of the side openings and greenhouse width on natural ventilation performance was analyzed by simulation. The necessary ventilation rate with different solar radiation transmittance increased significantly when the outside temperature grows higher. The necessary ventilation rate of 40% transmittance was about half of that of 90% transmittance. In consequence, shading effect on temperature control in greenhouse is significant in summer. When the total area of the openings for ventilation is constant, the maximum ventilation rate happens when the area of roof openings is equal to the area of side openings. This maximum ventilation rate is about 3 times of that of the greenhouse with roof openings and without side openings. Therefore, the side openings are advantageous to improve the natural ventilation in greenhouses. As the greenhouse width increases, the influence of side openings on the ventilation rate is becoming smaller. If the natural ventilation rate of the greenhouse with roof and side openings is to become double of that of the roof openings only, the width should be narrower than 38.4m for the Venlo type and 64m for Wide span type.

관상동맥우회 이식편으로서의 우위대망동맥의 조직학적 특징

이현우,송현,유동곤,임한중,이재원,송명근,Lee, Hyun-Woo,Song, Hyun,Yoo, Dong-Gon,Lim, Han-Jung,Lee, Jae-Won,Song, Meong-Gun 대한흉부심장혈관외과학회 1999 Journal of Chest Surgery (J Chest Surg) Vol.32 No.10

Long term patency of arterial graft has been better than venous graft and redo coronary artery bypass grafting has been increasing, therefore, there has been an increasing need for alternative arterial grafts except internal thoracic artery(ITA). Material and Method: Right gastroepiploic arteries(RGEA) were harvested from 100 patients who had received gastrectomy for gastric cancer or ulcer. ITAs were obtained from 10 patients undergoing coronary artery bypass grafting. The length of RGEA was measured from the pyloric ring. Items of the morphometric and histologic study at the pyloric ring and sites of the 10cm and 20cm RGEA from the pyloric ring were luminal diameter, intimal thickness, medial thickness, wall thickness, degree of intimal hyperplasia, intimal thickness, medial thickness, wall thickness, degree of intimal hyperplasia, intimal thickness index, medial thickness index, and the number of discontinuities of the internal elastic lamina. Similar items were applied to the proximal site of ITAs. Result: The length of RGEA was 23${\pm}$2.7cm(range 17∼31cm). Comparing the 20cm RGEA with ITA, intimal thickness, medial thickness, wall thickness, and degree of intimal hyperplasia did not show any difference(p>0.05). However, 20cm RGEA was greater than ITA at the luminal diameter, intimal thickness index, and the number thickness and wall thickness in each site of the RGEA(pyloric ring, 10cm, 20cm) decreased from the pyloric ring to the distal sites(p<0.05). The degree of intimal hyperplasia and the number of discontinuities of the internal elastic lamina did not show any difference between the pyloric ring and 10cm, however, those of 20cm were smaller than these sites(p<0.05). RGEA had more number of discontinuities of the internal elastic lamina and rich smooth muscle cells in the media than ITA. Conclusion: The length and diameter of RGEA is good enough to reach most of the coronary arteries. Moreover, long term patency of RGEA may be improved, if anastomosed in the distal site.

서초동(서울시 서초구)의 거미상

김주필(Joo Pil Kim),정혜리(Hye ri Jeong),김대희(Dae Hee Kim),박동우(Dong Woo Park),서재웅(Jae Woong Seo),이현우(Hyun woo Lee) 한국거미연구소 2017 한국거미 Vol.33 No.1

2016년 3월 31일부터 7월 31일까지 서울특별시 서초구 서초동에 위치한 서울고등학교 교정 일대를 서울고등학교 환경생물부 부원들이 채집 조사한 결과 20과 43속 53종의 거미가 조사 연구되어 이에 보고하는 바이다. From March 31st to July 31st in 2016, members of an environmental biology club at Seoul High School located in Seocho-gu, Seoul, Dae-Hee Kim, Dong-Woo Park, Jae-Woong Seo and Hyun-woo Lee, collected 20 families 43 genera 53 species of spiders and report the result of the study here.

가미대황고(加味大黃膏)의 멜라닌세포 활성억제가 자외선 조사로 인한 피부 손상 완화에 미치는 영향

이현우,홍승욱,Lee, Hyun-Woo,Hong, Seung-Ug 대한한방안이비인후피부과학회 2007 한방안이비인후피부과학회지 Vol.20 No.2

Objective : As a result of increasing amount of ultraviolet ray, skin problems including sunburn, rapid skin aging, melanoma, and even skin cancer continue to rise. In the present study, the effect of oriental herbal extract, Daehwanggo(大黃膏,DH) and Daehwanggogasnagbakpi(大黃膏加桑白皮,DS), as external application, on the skin damage, was investigated. Methods : 30 mice were equally distributed into 3 groups : control, UVB-control and UVB-irradiated and DS-treated group. Also mouse melanoma cell lines were cultured. Tyrosinase inhibition was measured to analyze the UN-protection effect. Melanogenesis in the UV-irradiated melanoma cell lines was compared in DS-treated cell line and control cell line. Sample skin from the ear tissue of the 3 groups were analyzed to observe the inflammatory response, T cell differentiation, apoptosis of keratinocytes. Results : The tyrosinase was more significantly inhibited in the DS group compared to DH group. Antioxidative effects was more prominent in DS group when superoxide dismutase was measured. Both the DS- and DH-treated cell lines showed significantly reduced melanogenesis. The reduction of external skin damage including erythematous papule, eczema, keratinocyte, pyopoiesis was observed in the DS- and DH-treated sample cells. In terms of the effect on the skin damage, sunburn cell, activated skin mast cells, secretion of IL-12, manifestation of HSP70, hyperplasia of epithelial cells, MMP-9 and destruction of the collagen were all significantly improved in the DS-treated sample cells. Melanin cells and the apoptosis in the melanoma cell line were decreased. Conclusion : DH and DS were traditionally applied externally for the scald in the oriental medicine. The present study elucidated the possibility of herbal extracts to be used as ultraviolet protectives. Further investigations are needed to assure the clinical application.

연구논문 : 시간에 종속되는 스트렝스 - 스트레스 모형연구 - 스트렝스가 변하는 경우 -

이현우,김재주 ( Hyun Woo Lee,Jae Joo Kim ) 한국품질경영학회 1996 품질경영학회지 Vol.24 No.3

A Case of Globus Hystericus caused by psychological, digestive disorder

이현우,장유진,홍승욱,Lee, Hyun-Woo,Chang, You-Jin,Hong, Seung-Ug The Society of Korean Medicine Ophthalmology 2013 한방안이비인후피부과학회지 Vol.26 No.2

Objectives : 본 연구를 통해 정신과적, 소화기성으로 유발된 히스테리성 구를 반하백출천마탕과 자음건비탕으로 치료한 1례를 보고하려 한다. Methods : 오심, 불면, 이명, 소화불량, 초조, 두통, 매핵기를 주소로 하는 23세 여성 환자를 대상으로 약 4개월 동안 침구, 반하백출천마탕과 자음건비탕으로 치료하였다. Results & Conclusions : 4개월 동안의 치료 후, 히스테리성 구와 다른 증상들이 소실되었다. 이 논문에서는, 소화기계 장애와 정신 질환 치료를 위해 오랫동안 사용되어온 반하백출천마탕과 자음건비탕을 히스테리성 구 치료에 이용하였다. 결론적으로, 본 연구는 히스테리성 구와 소화기계 장애가 밀접한 관련이 있음과 히스테리성 구에 대한 한의학적 치료의 중요성을 제시하였다.

소형화된 1.6 GHz 단일 채널 도플러 센서를 이용한 실시간 호흡 및 심장 박동 감지기

이현우,박일호,김동욱,Lee, Hyun-Woo,Park, Il-Ho,Kim, Dong-Wook 한국전자파학회 2007 한국전자파학회논문지 Vol.18 No.4

본 논문에서는 사람의 생체 신호를 감지하기 위해 1.6 GHz 단일 채널 도플러 센서와 아날로그 및 디지털 신호 처리부로 구성되어 있는 실시간 호흡 및 심장 박동 감지기를 개발하였다. 도플러 센서의 RF Front End는 발진기, 믹서, 저잡음 증폭기, 브랜치-라인 하이브리드, 그리고 패치 안테나로 구성되어 있다. 센서에 사용된 브랜치-라인 하이브리드는 기존의 하이브리드에 비해 40 % 정도 크기를 줄이면서도 상당히 유사한 성능을 가지도록 인공 전송 선로(artificial transmission line)를 사용하였다. 아날로그 신호처리부는 2차 Sallen-Key 능동 필터를 사용하여 제작되었고 디지털 신호 처리부는 LabVIEW를 사용하여 컴퓨터상에서 구현되었다. 개발된 시스템은 최대 50 cm 거리에서 사람의 호흡과 심장 박동을 측정함으로써 성능을 검증하였다. This paper presents a real-time respiration and heartbeat detector comprised of a 1.6 GHz single-channel Doppler sensor and analog/digital signal processing block for remote vital sign detection. The RF front end of the Doppler sensor consists of an oscillator, mixer, low noise amplifier, branch-line hybrid and patch antenna. We apply artificial transmission lines(ATLs) to the branch-line hybrid, which leads to a size reduction of 40 % in the hybrid, while its performance is very comparable to that of a conventional hybrid. The analog signal conditioning block is implemented using second order Sallen-Key active filters and the digital signal processing block is realized with a LabVIEW program on a computer. The respiration and heartbeat detection is demonstrated at a distance of 50 cm using the developed system.

보호구간이 없는 OFDM-CDMA 시스템의 성능 향상 기법

이현우,박중후,Lee Hyun-Woo,Park Joong-Hoo 한국통신학회 2006 韓國通信學會論文誌 Vol.31 No.5a

보호구간이 없는 Orthogonal Frequency Division Multiplexing-Code Division Multiplexing Access(OFDM-CDMA) 시스템을 사용하면 보호구간이 있는 OFDM-CDMA 시스템보다 대역폭 효율을 향상시킬 수 있다. 보호구간이 없는 OFDM-CDMA 시스템에서 Inter-Symbol Interference(ISI)와 Inter-Carrier Interference(ICI)를 제거하는 새로운 기법을 제안한다. 제안된 알고리즘은 Pseudo-Decorrelator에 기초하는 보호구간이 없는 OFDM-CDMA 시스템의 복조 기법이며, PD 알고리즘이라고 부르기로 하자. 모의실험 결과는 PD 알고리즘이 보호구간이 없는 OFDM-CDMA 시스템에서 ISI와 ICI를 효과적으로 제거할 수 있음을 보여준다. PD 알고리즘은 기존의 보호구간이 없는 OFDM-CDMA 시스템보다 좋은 BER 성능을 나타낸다. Orthogonal frequency division multiplexing-code division multiplexing access(OFDM-CDMA) systems without guard interval can enhance the bandwidth performance more efficiently than the systems with guard interval. In this paper, a new technique for an OFDM-CDMA system without guard interval, which can eliminate inter-symbol interference(ISI) and inter-channel interference(ICI), is presented. The proposed algorithm is a new demodulation technique, based on the Pseudo-Decorrelator, and it is named PD algorithm. Simulation results show that the PD algorithm can combat ISI and ICI efficiently for an OFDM-CDMA system without guard interval. The BER performance of the PD algorithm is much better than that of a conventional OFDM-CDMA system without guard interval.