반원형 리블렛 상부 난류경계층의 유동 구조 연구

이상현,이상준,Lee, Sang Hyun,Lee, Sang Joon 대한기계학회 1999 大韓機械學會論文集B Vol.23 No.7

The near-wall flow structures of turbulent boundary layer over riblets having semi-circular grooves were investigated experimentally for the drag decreasing ($s^+=25.2$) and drag increasing ($s^+=40.6$) cases. The field of view used for tho velocity field measurement was $6.75{\times}6.75mm^2$ in physical dimension, containing two grooves. One thousand instantaneous velocity fields over the riblets were extracted for each case of drag increase and decrease. For comparison, five hundreds instantaneous velocity fields over a smooth flat plate were also obtained under the same flow conditions. To see the global flow structure qualitatively, the flow visualization was also performed using the synchronized smoke-wire technique. For the drag decreasing case ($s^+=25.2$), most of the streamwise vortices stay above the riblets, interacting with the riblet tips. The high-speed in-rush flow toward the riblet surface rarely influences the flow inside tho riblet valleys submerged in the viscous sublayer. The riblet tips seem to impede the spanwise movement of the longitudinal vortices and induce secondary vortices. The turbulent kinetic energy in the riblet valley is sufficiently small to compensate the increased wetted area of the riblets. In addition, in the logarithmic region, the turbulent kinetic energy are small or almost equal to that of a smooth flat plato. For the drag increasing case ($s^+=40.6$), however, the streamwise vortices move into the riblet valley freely, interacting directly with the riblet inner surface. The penetration of the high-speed in-rush flow on the riblets increases tho skin-friction. The turbulent kinetic energy is increased in the riblet valleys and even in the outer region compared to that over a flat plate.

입력전류 파형 개선형 단상 정류기의 토폴로지

이상현(Sang-Hyun Lee),박진민(Jin-Min Park),문상필(Sang-Pil Mun),서기영(Ki-Young Suh) 한국조명·전기설비학회 2003 한국조명·전기설비학회 학술대회논문집 Vol.2003 No.-

For small capacity rectifier circuits such as these for consumer electronics and appliances, capacitor input type rectifier circuits are generally used. Consequently, various harmonics generated within the power system become a serious problem. Various studies of this effect have been presented previously. However, most of these employ switching devices, such as FETs and the like. The absence of switching devices makes systems more tolerant to over-load, and brings low radio noise benefits. We propose a power factor correction scheme using a LC resonant in commercial frequency without switching devices. In this method, it makes a sinusoidal wave by widening conduction period using the current resonance in commercial frequency, Hence the harmonic characteristics can be significantly improved, where the lower order harmonics, such as the fifth and seventh order are much reduced. The result are confirmed by the theoretical and experiment implementations.

콘크리트의 탄산화 관점에서 CO₂ 배출량-흡수량 평가에 관한 연구

이상현,이성복,이한승,Lee, Sang-Hyun,Lee, Sung-Bok,Lee, Han-Seung 한국콘크리트학회 2009 콘크리트학회논문집 Vol.21 No.1

콘크리트는 생산과정에서 다량의 이산화탄소를 배출하는 시멘트를 사용하기 때문에 반친환경적 재료로 인식되고 있다. 하지만 콘크리트는 사용기간 중 탄산화 과정을 통하여 대기중의 이산화탄소를 흡수한다. 이에 본 연구에서는 기존문헌 고찰을 통하여 1) 콘크리트 내 탄산화 가능한 물질의 농도, 2) 탄산화된 콘크리트의 체적, 3) 이산화탄소 분자량을 이용, 탄산화를 통한 콘크리트의 이산화탄소 흡수량의 정량적 산출 방법을 제시하였다. 또한 콘크리트 생산에 사용되는 재료들의 이산화탄소 배출량 자료를 이용하여 단위 콘크리트 생산에 따른 이산화탄소 배출량을 정량적으로 산출하였다. 이러한 콘크리트의 이산화탄소 흡수량 및 배출량의 정량적 산출방법을 이용하여 실제 사용중인 아파트 건축물 1동을 대상으로 하여 콘크리트의 생산에 따른 배출량과 사용기간에 따른 이산화탄소 흡수량을 정량적으로 산출하여 이산화탄소의 배출량-흡수량 평가를 실시하였다. 그 결과 건축물을 40, 60, 80년 사용시, 사용된 콘크리트의 이산화탄소 배출량 대 흡수량의 비율이 3.65, 4.47, 5.18%로 나타났다. 본 연구는 콘크리트 생산 및 사용에 따른 이산화탄소 배출량-흡수량의 정량적 산정방법에 연구의 목적을 두었으며 이산화탄소 배출량-흡수량 평가 결과 구조물을 80년 사용할 시 약 5.18%로 그 값이 미비하였으나 시멘트의 혼화재 치환율 증가를 통한 배출량 저감과 탄산화 체적 증가를 통한 이산화탄소 흡수량 증가를 통해 배출량-흡수량을 향상시킬 수 있으며, 향후 콘크리트의 이산화탄소 배출량-흡수량 평가에 본 연구의 방법이 유용하게 활용될 수 있을 것으로 판단된다. A concrete is considered unfriendly-environmental material because it uses cement which emits much $CO_2$ during producing process. However, a concrete absorbs $CO_2$ through carbonation process during service life. In this paper how much concrete absorbs $CO_2$ through carbonation was calculated using 1) concentration of carbonatable substances in concrete, 2) carbonated volume of concrete, 3) molecular weight of $CO_2$ based on references and the method was proposed. $CO_2$ emission from producing $1m^3$ concrete was calculated based on $CO_2$ emission datum of materials used in concrete. From using these methods that calculate $CO_2$ emission and absorption of concrete, assessment of $CO_2$ emission-absorption against a real apartment was conducted by subtracting absorption $CO_2$ according to service life from $CO_2$ emission in the process of making concrete. As a result, a ratio of absorption over emission of $CO_2$ through concrete carbonation according to service life 40, 60, 80 years was assessed about 3.65, 4.47, 5.18%. An objective of this study is to propose how to calculate emission - absorption of $CO_2$ from producing and using concrete. Although the result value, emission - absorption of $CO_2$, is 5.18% very low when the service life of an apartment is 80years, the value can be improved by reducing emission from using blended cement such as blast furnace slag or increasing replacement ratio of cement and increasing carbonated volume of concrete from expanding service life of a building. This study may be useful when $CO_2$ emission - absorption of concrete is evaluated in the further study.

추황배(Pyrus pyrifolia Nakai cv. Chuhwangbae) 과피로부터 1종의 Sterol과 3종의 배당체 화합물의 단리·동정

이유건(Yu Geon Lee1),조정용(Jeong-Yong Cho),이현주(Hyun Joo Lee),이용현(Yong Hyun Lee),이상현(Sang-Hyun Lee),한태호(Tae-Ho Han),김월수(Wol-Soo Kim),박근형(Keun-Hyung Park),문제학(Jae-Hak Moon) 한국식품과학회 2013 한국식품과학회지 Vol.45 No.5

본 연구에서는 배의 유용성 증명을 위한 일환으로 배의 화학성분을 분자수준에서 밝히고자 하였다. 이에 배 과피 MeOH 추출물을 용매분획하여 얻은 EtOAc-산성 분획과 EtOAc-중성분획을 대상으로 Sephadex LH-20, silica gel, 그리고 ODS colmn chromatography와 HPLC를 이용하여 정제 및 단리하였다. 그 결과, EtOAc-산성 분획과 EtOAc-중성 분획으로부터 각각 2종씩의 화합물을 단리하였다. 단리된 화합물 1-4는 1H- 및 13C-NMR 분석을 통하여 각각 (S)-(+)-2-cis-abscisic acid O-β-D-glucopyranosyl ester (화합물 1), 1-[4-O-β-D-glucopyranosyl]phenyl ethanone(piceoside, 화합물 2), β-sitosterol (화합물 3), 그리고 β-sitosteryl 3-O-β-D-glucopyranoside (화합물 4)로 동정되었다. 단리된 3종의 배당체 화합물(화합물 1, 2, 4)들은 본 연구에 의해 배로부터 처음 동정되었으며, 화합물 3은 추황배로부터 처음 동정되었다. 본 연구결과가 배 함유 성분연구는 물론 배의 기능성 해명 연구에도 추후 중요한 기초자료로 활용되길 기대한다. We isolated and identified antioxidants from acidic and neutral ethyl acetate fractions of the peel of pear (Pyrus pyrifolia N. cv. Chuhwangbae). We isolated 4 compounds from the methanol extract, by using 3 different types of column chromatography (Sephadex LH-20, silica gel, and octadecylsilane) and preparative HPLC. We identified the isolated compounds as (S)-(+)-2-cis-abscisic acid O-β-D-glucopyranosyl ester (compound 1), 1-[4-O-β-D-glucopyranosyl]phenyl ethanone (picroside, compound 2), β-sitosterol (compound 3), and β-sitosteryl 3-O-β-D-glucopyranoside (compound 4) by nuclear magnetic resonance analysis. We are the first to report the identification of compounds 1, 2, and 4 from pear.

Er:YAG laser를 조사한 치근면의 변화에 관한 연구

이상현,김영준,정현주,Lee, Sang-Hyun,Kim, Young-Jun,Chung, Hyun-Ju 대한치주과학회 2002 Journal of Periodontal & Implant Science Vol.32 No.2

This study was performed to evaluate the usability of Er:YAG laser for periodontal therapy. Forty dental root slabs ($5{\times}5{\times}2mm^3$) were prepared from human periodontally diseased extracted teeth and grouped into 4 groups: 1) control (root planing only), 2) root planing and irradiated with laser at 30mJ, 3) root planing and irradiated with laser at 60mJ, and 4) root planing and irradiated with laser at 100mJ. The root slabs were embedded in resin block before laser treatment. Er:YAG laser was irradiated under water irrigation with the tip held perpendicular to the root surface in contact mode. After Er:YAG laser irradiation or planing on the root surface, morphological changes have been observed under SEM, and the micro-hardness and Ca/P ratio were compared. 1. In the Control group, the root surface showed the directional change caused by root planing instrumentation, and the presence of smear layer, and no exposure of dentinal tubule was observed. Laser irradiated group showed surface changes with rough dentin surface of niche and depression and dentinal tubule exposure by the elimination of smear layer. 2. The micro-hardness of root surface in the laser irradiated group was higher than the control group. The higher energy output was applied, the higher micro-hardness on root surface was resulted. 3. The higher energy output was applied, the higher Ca/P ratio was observed. The higher Ca/P ratio in 60mJ group and 100mJ group was statistically significantly compared to the control group and the 30mJ group. These results suggest that Er:YAG laser irradiation on the periodontally diseased root surface could remove smear layer and increase the micro-hardness on root surface and Ca/P ratio which contribute to enhance the acid resistance of periodontally treated root surface.

개의 신장기능에 미치는 Guanabenz의 영향

이상현,고석태,Lee, Sang-Hyun,Ko, Suk-Tai 대한약학회 1988 약학회지 Vol.32 No.4

In this study attempts were made to observe the effects of guanabenz on renal function in dog, which manifests the antihypertensive action by inhibition of sympathetic tone through stimulating the presynaptic adrenoceptor (${\alpha}_2-adrenoceptor$). Guanabenz, when injected at a dose of $30.0{\mu}g/kg$, or infused at a dose of $3.0{\mu}g/kg/min$ intravenously, produced diuretic action with increased amounts of $Na^+\;and\;K^+$ in urine, and with decreased reabsorption rates of $Na^+\;and\;K^+$ in renal tubules. It was also observed that the rates of osmolar and free water clearances were increased, but the glomerular filtration rate and renal plasma flow were not changed. Guanabenz injected at a dose of $3.0{\mu}g/kg$ into a carotid artery or infused intravenously at a dose of $3.0{\mu}g/kg/min$ in a state of water diuresis elicited the diuretic action of the similar aspect as a case of guanabenz given intravenously. The diuretic action produced by guanabenz was completly blocked by pretreatment of i.v. prazosin, ${\alpha}_1-adrenoblocking$ agent, or of i.v. yohimbine, ${\alpha}_2-adrenergic$ blocking agent. Prazosin, when given into a renal artery, inhibited the diuretic action by i.v. guanabenz in only injected kidney, whereas in case of yohimbine the action was inhibited in both kidney. Guanabenz infused at a dose of $1.0{\mu}g/kg/min$ into a renal artery exhibited no significant changes of renal function in both kidney. In denervation experiments, guanabenz given intravenously produced typical diuretic action in innervated kidney, whereas in denervated kidney, it did not affect the action at initial period but exhibited the action with increase of only free water clearance at later period. These results suggest that guanabenz produced diuretic action in dog by inhibition of electrolyte reabsorption rates in renal tabules, mainly proximal tubule and of ADH release, which is mediated by stimulating of central sympathetic ${\alpha}_2-receptor$.

RapidEye 위성영상의 시계열 NDVI 및 객체기반 분류를 이용한 북한 재령군의 논벼 재배지역 추출 기법 연구

이상현,오윤경,박나영,이성학,최진용,Lee, Sang-Hyun,Oh, Yun-Gyeong,Park, Na-Young,Lee, Sung Hack,Choi, Jin-Yong 한국농공학회 2014 한국농공학회논문집 Vol.56 No.3

While utilizing high resolution satellite image for land use classification has been popularized, object-oriented classification has been adapted as an affordable classification method rather than conventional statistical classification. The aim of this study is to extract the paddy field area using object-oriented classification with time series NDVI from high-resolution satellite images, and the RapidEye satellite images of Jaeryung-gun in North Korea were used. For the implementation of object-oriented classification, creating objects by setting of scale and color factors was conducted, then 3 different land use categories including paddy field, forest and water bodies were extracted from the objects applying the variation of time-series NDVI. The unclassified objects which were not involved into the previous extraction classified into 6 categories using unsupervised classification by clustering analysis. Finally, the unsuitable paddy field area were assorted from the topographic factors such as elevation and slope. As the results, about 33.6 % of the total area (32313.1 ha) were classified to the paddy field (10847.9 ha) and 851.0 ha was classified to the unsuitable paddy field based on the topographic factors. The user accuracy of paddy field classification was calculated to 83.3 %, and among those, about 60.0 % of total paddy fields were classified from the time-series NDVI before the unsupervised classification. Other land covers were classified as to upland(5255.2 ha), forest (10961.0 ha), residential area and bare land (3309.6 ha), and lake and river (1784.4 ha) from this object-oriented classification.

에너지소산 제어 알고리듬의 제어이득 산정

이상현,강상훈,민경원,Lee Sang Hyun,Kang Sang Hoon,Min Kyung-Won 한국전산구조공학회 2004 한국전산구조공학회논문집 Vol.17 No.4

본 논문은 에너지소산 제어알고리듬의 제어이득 산정에 관하여 연구하였다. Lyapunov안정성이론에 기초하여 속도 되먹임 포화제어알고리듬, 뱅뱅제어 알고리듬 그리고 에너지게인 제어알고리듬을 제안하였고, 이 알고리듬의 성능을 평가하고 비교하였다. 속도 되먹임 포화제어알고리듬과 에너지게인 제어알고리듬에서는 포화현상을 고려하였고, 뱅뱅제어에서는 경계층을 이용하여 채터링현상을 고려하였다. 수치적인 해석을 통해서 제안된 제어알고리듬이 바람하중에 의해 야기되어지는 구조물의 에너지를 효과적으로 소산시킬 수 있음을 보여주었다. This study is on control gain estimation of energy dissipation control algorithms. Velocity feedback saturated, bang bang, and energy gain control algorithms are proposed based on the Lyapunov stability theory and their performances are evaluated and compared. Saturation problem is considered in the design of the velocity feedback saturated and energy-gain control algorithms, and chattering problem in bang bang control is solved by using boundary layer. Numerical results show that the proposed control algorithms can dissipate the structural energy induced by wind loads efficiently.

방약합편(方藥合編) 상통(上統) 처방(處方)에 대한 방제학적(方劑學的) 고찰(考察)

이상현,Lee, Sang-Hyun 대한한의학방제학회 2009 大韓韓醫學方劑學會誌 Vol.17 No.1

This report describes the studies as follows through the research of Basic-prescriptions about 123 prescriptions in high-chepter(上統) from Bang-Yak-Hap-Pyun(方藥合編). There are 24 Basic-prescriptions including Sagunja-tang(四君子湯), Samul-tang(四物湯), Sogeonjung-tang(小建中湯), lijung-tang(理中湯), Dangguibohyul-tang(當歸補血湯), Yijin-tang(二陳湯), Gauwon-chun(擧元煎), Jeongweon-eum(貞元飮), and Yukmichiwhang-won(六味地黃元), etc. about 123 prescriptions in high-chepter(上統) from Bang-Yak-Hap-Pyun(方藥合編). There were many cases compounding the Basic-prescriptions each other. So I investigated those cases. The results were the other typed (blended) Basic-prescriptions including Palmul-tang(八物湯), Sipjeondaebo-tang(十全大補湯), Yukgunja-tang(六君子湯), Bojungyikkee-tang(補中益氣湯), SsangHwa-tang(雙和湯), and Gwibitang(歸脾湯). And I investigated about pathologies in connection with these Basic-prescriptions. Oriental Medical Pathology applied with these Basic-prescriptions were Giheo(氣虛), hyulheo(血虛), Gihyulguheo(氣血俱虛), Biheohan(脾虛寒), Giheo-dameum(氣虛痰飮), Giheohaham(氣虛下陷), Sineumheo(腎陰虛), etc. These results indicated that 123 prescriptions in high-chepter from Bang-Yak-Hap-Pyun are composed of Bojei(補劑) to treatment against many kinds of Infirmity and promote physiological function.

지역 간 시계열 인구이동의 정량적 특징 분석 및 인구이동 네트워크의 연결중심성 분석

이상현,오윤경,Lee, Sang-Hyun,Oh, Yun-Gyeong 한국농공학회 2017 한국농공학회논문집 Vol.59 No.5

In this study, we visualized the regional migration in Korea from 2001 to 2015 using the Chord diagram which can represents amount of migration and flows at the same time. In addition, we constructed a migration network and analyzed the degree centrality of each region for identifying the main regions linking to various regions. In 2001~2005, most of population moved into Geonggi from various regions. However, the capital function was transferred to Sejong in 2011~2015, and population moving into Sejong and Chungnam was increased significantly. The main outflow of population in migration network were shown at the regions in Jeonbuk and Gyeongbuk province in 2001~2004, and recently the regions in Gyeongnam, Gyeonggi, and Seoul were identified as the main nodes in terms of outflow of population. We also focused on migration in rural area through degree centrality, and cord diagram in Chungnam, Jeonbuk, and Jeonnam where include the representative crop area. In 2015. there was the significant increase of migration from Gyeonggi to Chungnam, and internal migration within Jeonbuk increased rather than cross-border migration. In addition, migration from Jeonam to capital area decreased in 2015 but migration among cities within Jeonman increased. In particular, Yesan-gun showed the significant migration to other cities in Jeonnam. Population is necessary to develop community and sustain economic growth in rural regions. Therefore, migration is important for the transfer of manpower. The strength of this study is to approach the temporal change of migration from the viewpoint on quantitative and structural characteristics.