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.

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.

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.

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.

MR감쇠기를 장착한 토글가새시스템을 이용한 건축구조물의 지진응답제어

이상현,황재승,민경원,이명규,Lee Sang-Hyun,Hwang Jae-Seung,Min Kyung-Won,Lee Myoung-Kyu 한국전산구조공학회 2006 한국전산구조공학회논문집 Vol.19 No.3

본 연구에서는, 지진하중에 의해 구조물에 발생하는 진동을 제어하기 위하여 토글 시스템의 비선형성을 연구하고, 자기유변유체(MR) 감쇠기를 장착한 토글 가새시스템의 성능을 평가하였다. Bingham 모델로 표현되는 MR감쇠기의 제어력이 속도의 함수인 점을 고려하여, 토글 가새시스템에 의한 속도증폭계수를 계산하였고 토글 형태에 대한 증폭계수효과를 평가하였다. 특히 강한 지진하중에서 쉐브론과 대각가새 등의 전형적인 가새시스템에 장착된 MR감쇠기가 충분한 응답감소효과를 제공하지 못하는 경우에, 토글 가새시스템을 사용하여 제어성능을 크게 강화시키는 것을 수치해석 결과를 통하여 확인하였다. In this paper, the performance of a toggle brace-MR damper system is evaluated for the control of the structure excited by earthquake load and the non-linearity of the toggle system is investigated. Considering that the control force of MR damper described by Bingham model is a function of velocity, velocity amplification factor by the toggle brace system is calculated and the effect of toggle configuration on the amplification factor is also evaluated. Numerical results show that the control performance can be largely enhanced using toggle brace system especially for the case that the MR damper installed with conventional brace system such as Chevron and diagonal cannot provide enough control force under severe earthquake load.

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 ${\alpha}_2-receptor$.

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.

임플란트 나사산 디자인이 변연골 응력에 미치는 영향

이상현,조광헌,이규복,Lee, Sang-Hyun,Jo, Kwang-Heon,Lee, Kyu-Bok 대한치과보철학회 2011 대한치과보철학회지 Vol.49 No.4

연구 목적: 본 연구의 목적은 치과용 임플란트 나사산 디자인이 변연골 응력에 미치는 영향에 정량적인 분석을 하고자 한다. 연구 재료 및 방법: 외경 4.1 mm (경부직경 3.5 mm), 매식부 길이 10 m인 표준형 ITI 임플란트 시스템(ITI Dental Implant System; Straumann AG, Waldenburg, Switzerland)을 기본모델(대조모델)로 채택하고, 그 몸체의 나사산은 다른 임플란트 시스템에 채택되고 있는 삼각형, 사각형, buttres형 디자인을 가지는 가상의 해석모델을 4종 만들었다. 해석모델은 나사산 형태와 크기에 따라 (1) 모델 A (작은 삼각형 나사산), (2) 모델 B (큰 삼각형 나사산), (3) 모델 C (buttres형 나사산), 및 (4) 모델 D (사각형 나사산)로 구분하였다. 유한요소 모델링과 해석에는 NISA II/DISPLAY III (Engineering Mechanics Research Corporation, Troy, MI, USA) 프로그램을 사용하였다. Mesh 구성에는 NKTP type 34형 solid 요소(4각형 축대칭 요소, 요소당 절점수 8개)를 사용하여 임플란트 장축과 평행한 축대칭 하중은 물론 장축과 경사각을 갖는 비축대칭 하중조건을 모두 해석할 수 있도록 하였다. 임플란트의 표면으로부터 각각 0.2, 0.4, 0.6, 0.8, 1.0 mm 떨어진 위치에 5개의 응력관찰점(stress monitoring point)을 설정 하여 기록된 응력 값으로부터 회귀분석을 통하여 변연골 응력 최대값(peak stress)을 정량화하였다. 해석에 사용한 하중 조건은 2가지로, 임플란트 축에 평행한 수직하중 100 N과 임플란트 축과 $30^{\circ}$를 이루는 경사력 100 N 조건이었다. 결과: 임플란트 경부와 접하고 있는 인접 변연골에 응력집중현상이 보이고 있었으며, 그 양상은 임플란트 나사산 디자인과 무관하게 거의 유사하게 관찰되었다. 수직력 100 N 조건에서 산출된 변연골 최대응력값은 대조모델과 실험모델 A, B, C, D에서 7.84, 6.45, 5.96, 6.85, 5.39 MPa이었고, 경사력 조건에서는 각각 29.18, 26.45, 25.12, 27.37, 23.58 MPa이었다. 결론: 임플란트 나사산의 디자인은 변연골의 응력에 영향을 미치는 중요한 요소이다. Purpose: The purpose of this study was to investigate the effect of different thread designs on the marginal bone stresses around dental implant. Materials and methods: Standard ITI implant(ITI Dental Implant System; Straumann AG, Waldenburg, Switzerland), 4.1 mm in diameter and 10 mm in length, was selected as control. Test implants of four different thread patterns were created based on control implant, i.e. maintaining all geometrical design of control implant except thread pattern. Four thread designs used in test implants include (1) small V-shape screw (model A), (2) large V-shape screw (model B), (3) buttress screw (model C), and (4) trapezoid screw (model D). Surface area for unit length of implant was 14.4 $mm^2$ (control), 21.7 (small V-shape screw), 20.6 (large V-shape screw), 17.0 (buttress screw) and 28.7 $mm^2$ (trapezoid screw). Finite element models of implant/bone complex were created using an axisymmetric scheme with the use of NISA II/DISPLAY III (Engineering Mechanics Research Corporation, Troy, MI, USA). A load of 100 N applied to the central node on the crown top either in parallel direction or at 30 degree to the implant axis (in order to apply non-axial load to the implant NKTP type 34 element was employed). Quantification and comparison of the peak stress in the marginal bone of each implant model was made using a series of regression analyses based on the stress data calculated at the 5 reference points which were set at 0.2, 0.4, 0.6, 0.8 and 1.0 mm from implant wall on the marginal bone surface. Results: Results showed that although severe stress concentration on the marginal bone cannot be avoided a substantial reduction in the peak stress is achievable using different thread design. The peak marginal bone stresses under vertical loading condition were 7.84, 6.45, 5.96, 6.85, 5.39 MPa for control and model A, B, C and D, respectively. And 29.18, 26.45, 25.12, 27.37, 23.58 MPa when subject to inclined loading. Conclusion: It was concluded that the thread design is an important influential factor to the marginal bone stresses.

지패산(芷貝散)의 항염증(抗炎症) 효능(效能)에 대한 연구(硏究)

이상현,박찬기,Lee, Sang-Hyun,Park, Chan-Ki 대한한의학방제학회 2008 大韓韓醫學方劑學會誌 Vol.16 No.1

Although inflammatory mediators such as nitric oxide(NO) and pro-inflammatory cytokines are involved in host defense mechanism, these overproduction contributes to the pathogenesis of several diseases such as otitis media, hearing loss, periodontitis, bacterial sepsis, rheumatoid arthritis, chronic inflammation and autoimmune diseases. We investigate the anti-inflammatory effects of water extract from Ji-Pae-San(JPSWE) fomulated with Angelica dahurica plus Fritillaria Verticillata, Angelica dahurica(ADWE), and Fritillaria Verticillata(FUVE) in vitro and in vivo. Each extract inhibited the production of inflammatory mediators(NO, $IL-1{\beta}$, IL-6, $TNF-{\alpha}$, and prostaglandin $E_2$) and the expression of inducible NO synthase(iNOS) and cyclooxygenase-2(COX-2) in lipopolysaccharide(LPS)-stimulated RAW 264.7 macrophages in a dose-dependent manner. These inhibitory effects were synergistically increased by their combination. JPSWE also inhibited $TNF-{\alpha}$, $IL-1{\beta}$, IL-6. and $PGE_2$ production as well as COX activity in LPS-stimulated mice. Moreover, JPSWE significantly suppressed death by LPS-septic shock in mice(survival rate: 100%). These results suggest that Ji-Pae-San may be useful for therapeutic drugs against inflammatory immune diseases, probably by suppressing the production of inflammatory mediators.

아토피 피부염 치료 처방에 대한 방제학적(方劑學的) 고찰(考察)

이상현,윤용갑,Lee, Sang-Hyun,Yun, Yong-Gab 대한한방안이비인후피부과학회 2006 한방안이비인후피부과학회지 Vol.19 No.3

In Oriental Medicine, Atopic dermatitis(AD) belongs to the category of the Naseun, Taesun(胎癬), Taeryumchang(胎斂瘡), Eczema(濕疹), Seupchang(濕瘡), Samanpung(四彎風), Chimumchang(浸淫瘡). The Basic Prescriptions which have been used for treatment of Atopic dermatitis are saengryusamultang(生料四物湯), Onchungeum(溫淸飮), Seungmagalgeuntang(升麻葛根湯),Hoichunryangkyuksan(回春凉膈散), Doghengsan(導赤散), Pyungweesan(平胃散), Heungbangpaedoksan(荊防敗毒散), Goomigangharltang(九味羌活湯), Baekhotang(白虎湯), Gaegytang(桂枝湯), Yukmigihyuangtang(六味地黃湯). AD can divide three groups, Acute-Type, Semiacute-Type, Chronic-Type, according to it's condition. This study shows that it can be applicate Seungmagalgeuntang(升麻葛根湯), Hoichunryangkyuksan(回春凉膈散), Doghengsan(導赤散), Heungbangpaedoksan(荊防敗毒散), Goomigangharltang(九味羌活湯), Baekhotang(白虎湯), Gaegytang(桂枝湯) for treatment of Acute-Type, Pyungweesan(平胃散) for treatment of Semiacute-Type, and saengryusamultang(生料四物湯), Oncungeum(溫淸飮) for treatment fo Chronic-Type.