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.

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.

16~18세기 영·호남 누정에 깃든 문화경관의 의미론적 해석 - 지정 문화재를 중심으로 -

이현우,Lee, Hyun Woo 국립문화재연구원 2012 헤리티지:역사와 과학 Vol.45 No.1

본 연구는 국가지정 또는 시도지정 문화재 중 총 22개의 영 호남 소재 누정을 중심으로 16~18세기 명리를 등지고 초야에 은거한 사림(士林)의 누정 문화를 고찰함으로써, 조영자의 자연관과 누정건립 등의 문화형성과정에서 축적된 미의식을 구명하고자 하였다. 특히 본 연구에서는 개별 누정에 작용된 의미론적 경관특성을 밝히기 위한 제안으로 '풍수적 입지 누정명 분석 누정문학 분석' 등의 해석을 시도하였다. 본 연구를 통해 확인된 주요 결과는 다음과 같다. 누정의 '입지[風水] 명칭[懸板] 문학[板上詩]' 등의 분석 및 해석 결과를 토대로 한국 누정만이 갖는 특수성을 논한다면, 누정의 입지는 풍수가 지향하는 목표와 일맥상통함이 확인되었는데, 이는 땅의 모양(物形)을 의미론적 풍수형국으로 해석함으로써 은유적이면서도 풍자적으로 '터잡기' 한 특징에서도 잘 드러나고 있다. 특히 풍수형국론(風水形局論) 관점에서 본 누정의 입지는 배산임수의 요건을 모두 충족했으며, 지향했던 전형적인 좌향은 남동향임이 확인되었다. 또한 땅의 모양에 대한 직관적이거나 자연론적인 표현보다는, 서로 다른 의미를 부여하여 은유적이면서도 풍자적으로 표현함으로써, 전통적 경관짜임의 특징을 형이상학적인 해학(諧謔)으로까지 승화시키고자 하는 보편성이 발견된다. 더 나아가 누정의 입지를 광역적 경관인식 체계로 본 의미론적 낙토(樂土) 개념이 표출되고 있다. 한편 누정명은 누정이 위치한 서로 다른 개별적 경관을 응축함으로써 상정된 의미론적인 어휘였다. '누정명의 어의 분석'에서 가장 높은 빈도를 보인 것은 주변경관을 간명한 어휘로 함축한 것인데, 그 특징은 첫째 '자연예찬(自然禮讚)' 즉 승경(勝景) 및 사시경물(四時景物)에 대한 흥취, 둘째, '유가사상(儒家思想)'과 관련된 경서(經書) 문장(文章) 성리학적 가치관 중국의 고사성어, 셋째, '선현칭송(先賢稱頌)'에 관한 상고성(尙古性), 넷째, 유유자적과 안빈낙도의 전형으로 청빈하지만 자존적인 삶의 '풍류(風流)', 다섯째, '도가사상(道家思想)'과 관련하여 좌절된 자아를 달래기 위한 치유수단으로써의 '선경(仙境) 갈구' 등이 깊이 내포되어 있었다. 특이하게도 16세기 초반까지는 유가사상에 기반을 둔 명칭이 주류를 이루었지만, 16세기 중반을 넘기며 '자연예찬 및 선현칭송'의 제재가 증가하면서 유가사상에만 편중되지 않는 제재 상의 다양성을 보여준다. 이와 함께 문학이란 예술장르를 빌어 아름다운 자연에 비긴 작가의 심상을 투영시킴으로써 내면의 문제를 완곡히 토로한 누정문학의 주요한 특성으로는 '자연예찬 풍류 도가사상 및 유가사상 선현칭송' 등의 보편성과 '우국충정 연군지정 과거회상' 등의 키워드가 도출되었다. 그러나 이 당시 팽배했던 '성리학적 유교관'에도 불구하고 누정문학을 주도한 일의적(一意的) 개념이 '자연예찬 및 풍류'였음은 매우 주목할 만하다. This research has studied the building awareness of Nu-Jeong that a view of nature and aesthetic consciousness to unite the nature are inherent by considering Nu-Jeong of scholars who left fame and wealth behind and retired to hermitage in the backwoods in the 16~18 Century. This is to clarify correlation with leaving nature as it is, namely, an ideal state that scholars at the time would enjoy, through landscape awareness accepted into Nu-Jeong literature. In addition, this research has tracked the ideologic flow that acts on space formation by clarifying Korean unique meanings inherent to Nu-Jeong's cultural landscape. As a suggestion for this, the interpretation through 'Pungsu location Nu-Jeong name's analysis Nu-Jeong literature analysis', etc. was tried, so its integrated conclusion is as follows. It is not a chance that scholars of Joseon have left numerous literature works singing the nature. They already had huge interest and knowledge on the nature, and achieved active poetic exchange by sublimating the praise of nature as literature. Nu-Jeong, which was a place of exchange like this, had cleanliness of the nature and ideological purity as an oppositional space on turbid political realities. The Nu-Jeong literature drew the nature into a literature space as it is, without doing abstraction or ideation on the nature. The owner of Nu-Jeong exclusively possessed such natural landscape in grim and independent postures, so it provided a clue of Nu-Jeong cultural landscape that this research aimed to discuss. Scholars who aimed to raise wide and large vigor filled in between the sky and earth got to convince that people are born from the nature, grow in the nature and finally return to the nature. What people are born from the nature and finally return to the nature is just consistent with Taoistic and Zhua-ngzi thoughts denying human work, and leaving nature as it is or nature itself remained intact which is an ideal state. The construction at the time is a vessel containing the spirit of the times of the era. This thesis has proved that the Nu-Jeong culture of scholars located on the central line of Korean landscape was the flower of Joseon's scholar culture by interpreting it semantically.

정보숨김과 주변 움직임 벡터의 적응적 선택에 의한 에러은닉 알고리즘의 설계 및 구현

이현우,성동수,이건배,Lee, Hyun-Woo,Seong, Dong-Su,Lee, Keon-Bae 한국정보처리학회 2006 정보처리학회논문지B Vol.13 No.6

본 논문에서는, 복합 에러은닉 알고리즘을 이용하는 비디오 코더를 제안한다. 알고리즘은 먼저 정보숨김을 적용하여 손실된 블록의 움직임 벡터를 복원한다. 만일 은닉정보가 손실된 경우 손실된 블록의 움직임 벡터는 주위 정상 블록들의 움직임 벡터들의 적응적 선택을 이용하여, 손실된 블록의 새로운 움직임 벡터로 할당하고, OBMC (Overlapped Block Motion Compensation)를 통해 최종적으로 손실영역을 은닉하게 된다. 이 방법은 연속된 GOB의 손실에 있어서 좀 더 효과적임을 알 수 있었다. 실험 결과 제안한 방법의 결과가 정보숨김만을 이용하거나. 주변 움직임 벡터만을 이용하는 기존의 방법에 비하여 향상된 결과를 얻을 수 있음을 알 수 있었다. In this paper, we propose an error resilience video coder which uses a hybrid error concealment algorithm. Firstly, the algorithm uses the error concealment with data hiding. If the hiding information is lost, the motion vector of lost macroblock is computed with adaptive selection of adjacent motion vectors and OBMC (Overlapped Block Motion Compensation) is applied with this motion vector. We know our algorithm is more effective in case of continuous GOB. The results show more significant improvement than many temporal concealment methods such as MVRI (Motion Vector Rational Interpolation) or existing error concealment using data hiding.

3G LTE and SAE

이현우,Lee Hyun-Woo 한국통신학회 2006 정보와 통신 Vol.23 No.6

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.

시간에 종속되는 스트렝스 - 스트레스 모형연구 - 스트렝스가 변하는 경우 -

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

고속 공중 무선랜 시스템을 위한 효율적인 연결 요청 제어방법의 성능분석

이현우,김세한,류원,윤종호,Lee Hyun woo,Kim Se han,Ryu Won,Yoon Chong ho 한국통신학회 2005 韓國通信學會論文誌 Vol.30 No.3a

본 논문은 무선랜 기술을 활용한 초고속 무선인터넷 서비스에서 사용자 단말의 최대 성능을 얻기 위해 효과적으로 AP를 선택하고 연결을 설정하는 방식에 관한 것이다. IEEE 802.11에 기반한 공중 무선랜 환경에서 AP의 탐색과정을 수동형과 능동형으로 분류하고, 본 논문에서는 수동형 AP탐색 과정은 무선랜 접속장치(AP:Access Points) MAC계층에서 단말에 미디어 접근정보를 방송으로 알려주는 비콘(Beacon)프레임을 이용하고, 능동형 AP 탐색과정에서는 AP의 조사응답(Probe Response) 메시지 프레임을 이용하여 무선랜 단말에게 현재 AP에 연결(association)되어 있는 단말 갯수와 처리중인 트래픽량을 알려주는 방식을 제안한다. 단말에서는 RSSI, AP에 연결된 단말의 갯수와 처리하는 트래픽량의 정보를 종합적으로 검토하여 효율면에서 가장 유리한 AP를 선택하여 연결을 설정하면 다수의 사용자가 동시에 사용하는 핫스팟 환경에서도 최대성능을 얻을 수 있으며, 사업자입장에서는 사용자의 분산으로 자원과 망 관리 효율 면에서 상당한 효과가 있음을 시뮬레이션을 통하여 검증하였다. This paper generally relates to the field of wireless local area networks(WLANs), and more particularly, to AP selection and association methods for the performance of a station. In these days, IEEE 802.11 Wireless LAN network is widely deployed and used as an emerging service to connect high-speed Internet in the public wireless environment. But, if there are many users in hot spot area, they suffer a severe decrease of performance. Thus it needs an association and access control mechanism especially when it is used in the public environment. In this paper, we suggest a selection and association method using Beacon or Probe Response frames based IEEE 802.11. Station selects AP using the information of the capacity area in a Beacon or a Probe Response frame. According to the present paper, an association method for a public WLAN service, which includes a WLAN user terminal and an AP for relaying WLAN communications to and from the user terminal, includes the steps of the user terminal asking the AP's states for access to a radio channel; and the station selects and associates with the AP According to the above-described selection in a high speed wireless Internet service based on public WLAN technologies that are currently in operations. Further, it is possible to improve the efficiency of network management.