성형용 코어면 DLC 코팅에 의한 비구면 Glass렌즈 광학적 특성에 관한 연구

김현욱,차두환,이동길,김상석,김혜정,김정호,정상화,Kim, Hyun-Uk,Cha, Du-Hwan,Lee, Dong-Gil,Kim, Sang-Suk,Kim, Hye-Jeong,Kim, Jeong-Ho,Jeong, Sang-Hwa 한국광학회 2007 한국광학회지 Vol.18 No.5

본 연구에서는 3 메가픽셀, 2.5배 줌 카메라폰 모듈용 비구면 유리렌즈 개발을 목적으로 실험계획법(DOE)을 적용하여 성형용 초경 코어의 연삭가공조건을 구하고, 이를 활용하여 비구면 Glass렌즈 성형용 초경합금(WC) 코어를 초정밀 연삭가공을 수행하였다. 또한 가공된 성형용 코어의 가공면 위에 이온증착법으로 다이아몬드상 탄소(Diamond-Like Carbon; DLC) 코팅을 수행하여 DLC 코팅이 성형용 코어의 형상정도(PV)와 표면조도(Ra)에 미치는 영향을 평가하였으며, 비구면 Glass렌즈를 동일한 조건에서 성형하여 성형렌즈의 광학적 특성을 비교하여 성형용 코어면의 DLC 코팅 효과에 대하여 검토하였다. In this research, the optimal grinding condition has been obtained by design of experiment (DOE) fur the development of aspheric lens for the 3 Mega Pixel, 2.5x optical zoom camera-phone module. Also, the tungsten carbide (WC) mold was processed by the method of ultra precision grinding under this optimal grinding condition. The influence of diamond-liked carbon (DLC) coating on form accuracy (PV) and surface roughness (Ra) of the mold was evaluated through measurements after DCL coating using ion plating on the ground mold. Also, aspheric glass lenses were molded, some before DLC coating of the mold and some after the DLC coating. The optical characteristics of each sample, molded by the different molds, were compared with each other.

식물의 산업용 지방산 생산을 위한 오일합성 유전자의 기능과 이용 전망

김현욱,이경렬,박종석,노경희,김순희,김종범,Kim, Hyun-Uk,Lee, Kyeong-Ryeol,Park, Jong-Sug,Roh, Kyung-Hee,Kim, Sun-Hee,Kim, Jong-Bum 한국식물생명공학회 2010 식물생명공학회지 Vol.37 No.2

식물 종자오일의 지방산은 인간에 필수 지방산을 공급하는 식용 및 생필품 생산에 필요한 다양한 산업원료로 사용된다. 식물 오일의 식용 및 산업용 적합성과 경제성을 극대화하기 위해 유전공학에 의한 종자오일의 양과 지방산 조성 변형을 위한 대사조절연구가 계속 진행되고 있다. 하지만 식물에 일반적으로 존재하지 않는, 산업적으로 유용한 특이지방산의 합성과 종자오일로의 축적은 한계가 있음이 알려져 있다. 그 이유는 재배가 용이하며 생산성이 높은 오일식물의 acyltransferase가 특이지방산에 대한 기질특이성이 떨어지며 또한 특이지방산에 대한 세포막지질에서 종자오일로 전환시키는 편집기작 (editing mechanism)이 없기 때문으로 사료된다. 최근에 모델식물의 종자오일의 축적에 관여하는 acyltransferase에 관한 유전자들이 클로닝되었고, 특이지방산이 합성되는 인지질에서의 편집기작에 관여하는 acyltransferase 유전자들이 밝혀져 이들 유전자들의 정보를 이용하여 특이지방산을 효과적으로 생산.증진할 수 있는 기술이 개발될 수 있을 것으로 기대한다. 피마자오일의 주성분인 산업용 특이지방산인 리시놀레인 지방산을 오일식물에서 생산하기 위해 이에 관여할 것으로 추정되는 11개의 acyltransferase 유전자를 피마자 유전체 데이터베이스에서 존재함을 확인하였다. 이들 유전자들의 도입에 의해 형질전환 식물이 갖고 있지 않은 리시놀레인산에 대한 기질 특이성을 부여하여 종자오일 내의 특이지방산의 생산을 증가시킬 것으로 기대된다. Fatty acids in seed oil from plants are essential for human nutrients and have been used for industrial purpose. The growing demands of seed oil as food resources and feedstocks for industrial uses have attempted to modify fatty acid composition and to increase oil content in transgenic plants. However, production of unusual fatty acids in transgenic plants are limited, which is not synthesized the level same as original plants. This bottleneck was common for production of several unusual fatty acids in transgenic plants and suggests that there is different for substrate preference in oil metabolic pathway enzymes between host oil plants and original wild plants. Review of acyltransferases involved in acyl-editing and seed oil accumulation of oil plant and wild-plant producing unusual fatty acids will design strategies to maximize the production of unusual fatty acids in transgenic plants. In here, we identified eleven acyltransferase genes in castor based on sequence homology, which will be useful to increase hydroxy unusual fatty acids in transgenic plants.

비구면 Glass 렌즈 성형용 초경합금(WC) 코어의 DLC 코팅 효과

김현욱,정상화,박용필,김상석,김혜정,김정호,Kim, Hyun-Uk,Jeong, Sang-Hwa,Park, Yong-Pil,Kim, Sang-Suk,Kim, Hye-Jeong,Kim, Jeong-Ho 한국전기전자재료학회 2006 전기전자재료학회논문지 Vol.19 No.11

There have been intensive and continuous efforts in the field of DLC coating process because of their feature, like high hardness, high elasticity, abrasion resistance and chemical stability and have been applied widely the industrial areas. In this research, optimal grinding condition was investigated using Microlens Process Machine for the development of aspheric glass lens which is to be used for mobile phone module with 3 mega pixel and 2.5X optical zoom, and tungsten carbide(WC) mold cote was manufactured using high performance ultra precision machining and the effects of DLC coating on the form accuracy(PV) and surface roughness(Ra) of WC mold core was evaluated.

성형용 초경합금(WC) 코어면의 Re-Ir 코팅이 형상정도와 표면조도에 미치는 영향에 관한 연구

김현욱,김상석,김혜정,김정호,Kim, Hyun-Uk,Kim, Sang-Suk,Kim, Hye-Jeong,Kim, Jeong-Ho 한국전기전자재료학회 2007 전기전자재료학회논문지 Vol.20 No.9

Aspheric glass lens have recently been used in camera phone module because they are more effective than spherical ones. In this paper, the grinding condition of the tungsten carbide molding core has been found after applying DOE to the development of the aspheric glass lens for the 3 Megapixel and 2.5x camera-phone module. Also, the ultra precision grinding process was investigated under this condition by experiment. Re-Ir coating was applied on the ground surface of the tungsten carbide molding core. The influence of Re-Ir coating on the form accuracy and surface roughness of molding core was compared and evaluated. The form accuracy and surface roughness of the molding core were improved by application of Re-Ir coating on the surface of the tungsten carbide molding core.

산성환경에서 Lactobacillus casei YIT9018 의 생존에 관한 연구

김현욱,유광현,이돈성,고준수 ( Hyun Uk Kim,Kwang Hyun You,Don Sung Lee,Jun Soo Goh ) 한국축산학회 1980 한국축산학회지 Vol.22 No.4

Behavior of Lactobacillus casei YIT9018 has been studied in acidic media !MRS and skim milk broth) using three most common acids (acetic, lactic, citric acid) for their survival and the factors affecting their acid tolerance. Survival and death of L. casei YIT9018 were dependent on the concentration and the kinds of acids present in the media. In MRS broth, about 120 mM of lactic acid appeared to be the critical acid concentration for the survival of this useful lactic acid bacterial species. At the same molar concentration of the acids studied, citric acid was the most inhibitory, lactic acid is the next, and acetic acid was the least inhibitory acid to the survival of L. casei YIT9018 in MRS broth. Chemical structure of the acids and pH of acidified media appeared to affect the growth and the survival of this bacterium. Peptone, sucrose, and skim milk powder demonstrated varying degree of the protection for the survival of L.casei YIT9018 in acidified MRS broth. Skim milk was the most protective, peptone was the next, and sucrose was the least protective additive. Synergistic effects were observed when mixtures of acids were used in acidifying the media. Mixture of lactic and citric acid was the most inhibitory and the synergistic inhibition was stronger in MRS broth than in skim milk broth.

일반 시설물의 지반-구조물 상호작용 해석 기준에 대한 고찰

김현욱,하정곤,김동수,주광호,Kim, Hyun-Uk,Ha, Jeong-Gon,Kim, Dong-Soo,Joo, Kwang-Ho 한국지진공학회 2017 한국지진공학회논문집 Vol.21 No.5

This study reviews concepts, theories and formulas included in standards on soil-structure interaction and also shows practical example of application for engineers. Real structures are 3 dimensional and multi degree of freedom but they are often idealized to single degree of freedom for convenience. In this study, detailed procedures to calculate soil spring constants and damping coefficients and method to model soil-structure system are explained. Additionally, case studies to judge fixed base condition and evaluation of applicability of simple analysis method based on response spectra are performed.

자기조직화지도를 활용한 동일강수지역 최적군집수 분석

김현욱,손철,한상옥,Kim, Hyun Uk,Sohn, Chul,Han, Sang-Ok 대한공간정보학회 2012 한국공간정보학회지 Vol.20 No.6

우리나라의 동일강수지역에 대한 구분은 기상학적으로 의미를 지닐 뿐만 아니라 장기예보를 위한 자료로 활용된다. 또한 최근 들어 수문학에서는 확률강수량을 산정하기 위해 지금까지 사용되어 온 지점빈도해석의 단점을 보완한 지역빈도해석방법의 활용이 적극 제시되고 있다. 이에 따라 동일강수지역의 군집화에 대한 연구의 필요성이 증가하게 되었다. 본 연구에서는 1980년부터 2010년까지 61개 지상관측지점의 자료를 이용하여 자기조직화지도 군집기법으로 동일강수 지역을 군집화하고 K-means Clustering과 Davies-Bouldin Index를 적용하여 우리나라의 동일강수지역에 대해 6개의 최적 군집 개수를 산출하였다. 그리고 최종적으로 GIS에 기반한 Thiessen Polygon을 활용하여 동질지역의 지역화 하였다. In this study, homogeneous regions for regional frequency analysis were identified using rainfall data from 61 observation points in Korea. The used data were gathered from 1980 to 2010. Self organizing map and K-means clustering based on Davies-Bouldin Index were used to make clusters showing similar rainfall patterns and to decide the optimum number of the homogeneous regions. The results from this analysis showed that the 61 observation points can be optimally grouped into 6 geographical clusters. Finally, the 61 observations points grouped into 6 clusters were mapped regionally using Thiessen polygon method.

압전구동기를 이용한 초정밀레이저 가공의 고주파진동 장치설계

김현욱,황동현,박종권,조성학,이문구,Kim, Hyun-Uk,Hwang, Dong-Hyun,Park, Jong-Kweon,Cho, Sung-Hak,Lee, Moon-G. 한국생산제조학회 2010 한국생산제조학회지 Vol.10 No.6

To machine the micro hole, laser machining system is widely used, however, the system cannot fabricate the micro hole with high aspect ratio and good surface finish. To break the obstacles, the high frequency vibration mechanism with PZT (Piezoelectric Transducers) is proposed in this paper. The mechanism will vibrate the laser beam in vertical direction so that the aspect ratio and surface finish may be higher than the conventional. The mechanism vibrates the eyepiece of laser optics. In addition to the benefits, the mechanism enables us to have high precision and flexibility. It decreases burr and debris during machining. And it is able to machine various materials of workpiece. This research include high frequency and large travel range of the proposed mechanism. The PZT motion of mechanism and analysis on the sensitivity of design parameters are extracted from a finite element method (FEM) simulation. In the analysis, the target vibration mode without parasitic motion is designated to have the target frequency and high amplitude.

적설의 동질지역 구분과 지역 차등화

김현욱,심재관,최병철,KIM, Hyun-Uk,SHIM, Jae-Kwan,CHO, Byung-Choel 한국지리정보학회 2017 한국지리정보학회지 Vol.20 No.3

대설은 우리나라의 법적 자연재해 중 하나이다. 최근 기상현상에 의한 사회경제적 영향력을 함께 예보하는 영향예보가 부각되고 있으며, 이를 위해서는 먼저 각 지역의 기후적 특징을 분석할 필요가 있다. 본 연구에서는 영향예보의 기반마련을 위해 자기조직화지도를 활용하여 적설동질지역을 구분하여 지역별 적설 특징을 분석했다. 연구결과 적설동질지역은 7개 군집으로 나타났으며, 강설량 및 관측일수, 최대강설량을 이용하여 각 그룹의 특징을 구분했다. 대관령, 강릉시, 정읍시는 강설량이 많은 지역으로, 경상도는 강설량이 적은 지역으로 구분되었다. 선행연구와 비교결과 대표적인 지역이 잘 구분되었으나 강설의 특징은 차이가 있는 것으로 나타났다. 본 연구의 결과는 각 지역의 영향예보를 위한 정책결정에 기초자료로 활용될 수 있다. Snowfall is an important natural hazard in Korea. In recent years, the socioeconomic importance of impact-based forecasts of meteorological phenomena have been highlighted. To further develop forecasts, we first need to analyze the climatic characteristics of each region. In this study, homogeneous regions for snowfall analysis were classified using a self-organizing map for impact-based forecast and warning services. Homogeneous regions of snowfall were analyzed into seven clusters and the characteristics of each group were investigated using snowfall, observation days, and maximum snowfall. Daegwallyeong, Gangneung-si, and Jeongeup-si were classified as areas with high snowfall and Gyeongsangdo was classified as an area with low snowfall. Comparison with previous studies showed that representative areas were well distinguished, but snowfall characteristics were found to be different. The results of this study are of relevance to future policy decisions that use impact-based forecasting in each region.

펄스 레이저 스캐닝 기반 초음파 영상화 기술을 활용한 배관 구조물 손상 진단

김현욱 ( Kim Hyun Uk ),이지성 ( Lee Jisung ),이창길 ( Lee Changgil ),박승희 ( Park Seunghee ) 한국구조물진단유지관리공학회 2013 한국구조물진단유지관리공학회 학술발표대회 논문집 Vol.17 No.1