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다공성 3차원 Ti 지지체의 제조 및 알카리처리에 따른 생체활성 평가
안상현,김승언,김교한,윤희숙,현용택,An, Sang-Hyun,Kim, Seung-Eon,Kim, Kyo-Han,Yun, Hui-Suk,Hyun, Yong-Taek 한국재료학회 2009 한국재료학회지 Vol.19 No.7
Ti scaffolds with a three-dimensional porous structure were successfully fabricated using powder metallurgy and modified rapid prototyping (RP) process. The fabricated Ti scaffolds showed a highly porous structure with interconnected pores. The porosity and pore size of the scaffolds were in the range of 66$\sim$72% and $300\sim400\;\mu$m, respectively. The sintering of the fabricated scaffolds under the vacuum caused the Ti particles to bond to each other. The strength of the scaffolds depended on the layering patterns. The compressive strength of the scaffolds ranged from 15 MPa to 52 MPa according to the scaffolds' architecture. The alkali treatment of the fabricated scaffolds in an aqueous NaOH solution was shown to be effective in improving the bioactivity. The surface of the alkali-treated Ti scaffolds had a nano-sized fibre-like structure. The modified surface showed a good apatite forming ability. The apatite was formed on the surface of the alkali treated Ti scaffolds within 1 day. The thickness of the apatite increased when the soaking time in a simulated body fluid (SBF) solution increased. It is expected that the surface modification of Ti scaffolds by alkali treatment could be effective in forming apatites in vivo and can subsequently enhance bone formation.
안상현,임유진,유현,Ahn, Sang-Hyun,Lim, Yu-Jin,Yu, Hyun 한국정보처리학회 2009 정보처리학회논문지 C : 정보통신,정보보안 Vol.16 No.6
시간과 장소에 상관없이 인터넷 서비스를 제공 받고자 하는 인터넷 사용자들의 요구가 증가함에 따라 MANET(Mobile Ad-Hoc Network) 환경에서도 인터넷 연결성을 제공하기 위한 연구들이 주목을 받고 있다. 기존 DHCP(Dynamic Host Configuration Protocol) 기반 방식의 경우는 망 내 노드들에게 주소를 할당하기 위하여 다중 홉 거리에 있는 DHCP 서버와 메시지를 교환해야 하기 때문에 메시지 손실이 쉽게 발생할 수 있으며, 이로 인해 주소 설정의 안정성이 감소하고 주소 설정 시간이 증가하는 문제점이 있다. 따라서 본 논문에서는 노드가 DHCP 서버로부터 하나의 주소만을 할당 받는 것이 아니라 일정 크기의 주소 영역을 할당 받을 수 있게 하였다. 또한 주소 영역을 할당 받은 노드가 이웃의 주소 요청 노드들에게 자신의 주소 영역 중 일부를 할당할 수 있도록 하는 새로운 주소 설정 기법을 제안하였다. 모의 실험을 통하여 제안 기법이 기존 DHCP 기법에 비하여 주소 설정 시간과 제어 메시지 수 측면에서 각기 77%와 61%의 성능을 향상시킬 수 있음을 보였다. As it becomes increasingly important that Internet access is available anywhere at any time, providing MANET (Mobile Ad-Hoc Network) with the Internet access attracts more attention. The existing DHCP (Dynamic Host Configuration Protocol) address configuration schemes require message exchanges between MANET nodes and the DHCP server through multi-hop routes. Messages can be easily dropped in the wireless multi-hop communication environment and the address configuration may be instable and need long delay. In this paper, we propose a new address configuration scheme using the concept of address pool allocation. In the proposed scheme, the DHCP server assigns a part of its address pool to a node instead of a single address and the node can assign a part of its own address pool to its neighbor nodes. Through simulation studies, we show that our scheme yields about 77% of the address configuration delay and 61% of the control message overhead of the existing DHCP based mechanism.
강 슬리브 파단 직선 슬리브의 장력 및 열적 특성 분석 연구
안상현,김병걸,김상수,손홍관,박인표,김성규,Ahn, Sang-Hyun,Kim, Byung-Geol,Kim, Sang-Shu,Sohn, Hong-Kwan,Kim, In-Pyo,Kim, Sung-Kyu 한국전기전자재료학회 2008 전기전자재료학회논문지 Vol.21 No.11
According to previous report, aged sleeves of old transmission line showed several defaulted installation patterns, which was biased or corrosive-fractured of steel sleeve installed cases. These defects can cause serious accidents such as rapid increasing of sag or falling out of overhead conductor from sleeves. Consequently, the defects lead to the major power outage. Corrosion of steel sleeve is a typical defect by aging of sleeves. And it occupied almost 25 percent of investigated aged sleeves. This paper studied thermal properties and tension for ACSR conductor in case of fractured steel sleeve model by corrosion. The temperature distribution within overhead conductor has a specific gradient. Thermal properties of splice connectors(sleeve and clamp) showed normal behavior. However, mechanical properties were worse than normal sleeves. The detailed results were presented in the text.
건설사업관리(CM) 관리인력 규모산정을 위한 사례연구 - 공공공사 건축공사 사례를 중심으로 -
안상현,김진대,Ahn, Sang-Hyun,Kim, Jin-Dae 한국건설관리학회 2013 한국건설관리학회 논문집 Vol.14 No.4
국내 CM현장은 경기침체로 인해 성장이 다소 둔화되고 있지만 최근 공공기관 이전사업 등으로 인해 CM시장은 꾸준한 규모를 보이고 있다. CM제도가 도입된 이래로 다수의 발주기관들이 건설사업관리 역량을 점차 보유하고 있지만 이에 대한 건설사업관리 조직 규모 산정을 위한 노력은 미흡한 실정이다. 본 연구에서는 공공공사 건축공사 10개소 사례를 바탕으로 통계분석과 관리인력당 사업비를 활용하여 건설사업의 관리업무를 수행하는 전체 관리조직의 규모 산정 방법을 도출하였고 Case Study를 통해 활용성을 검토하고자 하였다. 이를 통해 적정 관리인력 규모 산정 및 투입으로 건설사업의 원활한 업무수행과 성공적으로 사업을 수행하는데 기여하고자 하였다. While growth of domestic CM market has slowed down due to economic recession, it recently shows sign of scale as some public agencies are relocating their headquarters. Since the introduction of CM system, a number of client organizations have acquired construction project management capabilities, however, sufficient efforts are not made to estimate the size of construction project management organization. This study drew a method for estimating the size of the organization managing construction project by utilizing statics analysis and project costs per member based on 10 public construction projects and tried to review applicability through case studies. With this study, we would like to make a contribution to achieving smoother work performance and success of the construction project by estimating and allocating proper scale of management workforce.
안상현,신영철,An. Sang-Hyun,Shin. Young-Chun 한국방재학회 2008 한국방재학회논문집 Vol.8 No.4
현재는 기술적인 발전을 토대로 정보의 요구수준이 상당부분 증대되었으며 GIS (Geographic Information System)분야 또한 더 많은 정보를 보다 신속하고 정확하게 처리 되어지고 있다. 특히 산불에 있어서는 산불발생시 공간적으로 넓은 지역을 신속히 분석하여 진화의 기초자료로 활용함으로써 환경적, 경제적, 인명적 피해를 최소화하고 대피경로, 확산경로 및 진화자원의 효율적 배치를 결정하는데 필수적이다. 이러한 산불확산에 영향을 미치는 인자 중에서 경사에 따른 산불확산속도를 규명하기 위하여 경사 및 경사방향에 따른 실험을 실시하였다. 실험결과 상향경사의 경우 경사가 증가할수록 시간이 감소하고, 하향경사에서는 증가하는 경향을 나타내었다. 실험결과 값을 토대로 상향경사는 (+), 하향경사는 (-)로 구분하여 경사에 따른 산불확산속도를 계산하였으며, 이러한 결과는 정확한 산불확산예측을 하는데 기여함으로써 효과적인 산불진화에 도움을 줄 수 있을 것으로 판단된다. As Information Technology developed, Information requirement has been went higher. In the field of GIS(Geographic Information System) more information is processed more quickly and accurately. Especially, quick analysis of forest fire information (topography, ignition point, weather condition, etc.) over a wide area is essential in order to minimize victim, environmental damage, and economical damage, decide course of evacuating, estimate a fire spread course, and attack resource arrangement. We determined a fire spread distance at each unit time through an experiment with various slope degrees and distinction of flat, upslope and downslope. For the tests on the upslope, as the slope increased, the rate of spread increased. On the downslope in contrast with the upslope, as the slope increased, the rate of spread decreased. We analyzed a spread rate of forest fire on each slope as the method classified upslope(+) and downslope(-) using the results obtained from the experiment. Consequently, the proposed method is able to be used to effectively support the attack of forest fire by providing accurate predictions of fire spread.
두시 하태독법이 시행된 비만 생쥐에서 Th2 분화조절을 통한 알러지성 비염 유발 감소 효과
안상현,김기봉,Ahn, Sang Hyun,Kim, Ki Bong 대한한방소아과학회 2018 대한한방소아과학회지 Vol.32 No.2
Objectives This study investigated the effects of Hataedock treatment with Douchi on induction of allergic rhinitis in obese induced NC/Nga mice. Methods NC/Nga mice were divided into control group (Ctrl), allergic rhinitis induced obese mice group (ARE), and allergic rhinitis induced obese mice group with Douchi Hataedock treatment (FGT). The 3-week-old mice of the FGT group were given one 10 mg/kg dose of Douchi Hataedock extract and sensitized with allergic antigens at weeks 4, 5, and 6. After 1 week of final sensitization, allergic rhinitis was induced primarily in mice nasal cavities for five days. After one week of the completion with the first induction, the second induction was introduced by the same method. After 1 week, few samples of the nasal mucosal tissues of each group were prepared. The factor of Th2 differentiation and inflammation control such that IL-4, STAT6, CD40, $Fc{\varepsilon}RI$, substance P, MMP-9, $NF-{\kappa}B$ p65, p-IkB, iNOS and COX-2 were observed by immunohistochemistry. Also, the difference in nasal mucosal injury was observed by histochemical method (PAS staining). Results The FGT group showed that reduced IL-4 production, STAT6 expression and CD40 expression by regulating excessive Th2 differentiation. Also, production of substance P and MMP-9 and activity of $Fc{\varepsilon}RI$ in mast cells were decreased. Inhibition of $NF-{\kappa}B$ p65 activity was induced by inhibition of p-IkB, and the production of inflammatory enzymes iNOS and COX-2 were decreased. In addition, the damage of intramural respiratory epithelium was low and excessive mucin secretion in goblet cells was low. Conclusions This study confirmed the possibility of controlling the allergic rhinitis in obese children who are expected to have an overactive inflammation.
황금 (Scutellaria baicalensis) 추출물의 ECS조절을 통한 아토피피부염 염증 완화 효과
안상현,김기봉,Ahn, Sang Hyun,Kim, Ki Bong 대한한방소아과학회 2021 대한한방소아과학회지 Vol.35 No.3
Objective The purpose of this study was to confirm the effect of Scutellaria baicalensis extract on skin damage recovery and inflammation relief in atopic dermatitis-induced mice through Endocannabinoid system (ECS) control. Methods 6-week-old Balb/C mice were divided into control group (Ctrl), atopic dermatitis induced group (ADE), palmitoylethanolamide (PEA) administered group after atopic dermatitis induced (PEAT), and Scutellaria baicalensis extract administered group after atopic dermatitis induced (SBT). Seven animals were assigned for each group. After drug administration for 3 weeks after inducing atopic dermatitis, Claudin and 8-OHdG were observed to confirm the recovery of the skin damage in each group. To confirm ECS regulation, CB1, CB2, and GPR55 were observed. To confirm the anti-inflammatory effect, Fc ε receptor, and MMP-9 was observed. Results Claudin positive reaction was significantly increased in SBT compared to ADE and PEAT. 8-OHdG positive reaction was significantly decreased in SBT compared to ADE and PEAT. CB1, CB2, and GPR55 positive responses were significantly increased in SBT compared to ADE and PEAT. Fc ε receptor and MMP-9 positivity were significantly decreased in SBT compared to ADE and PEAT. Conclusion It was confirmed that the Scutellaria baicalensis extract can reduce the inflammation of atopic dermatitis by restoring the structural damage of the skin lipid barrier through ECS activity.
안상현,유정호,김창덕,Ahn, Sang-Hyun,Yu, Jung-Ho,Kim, Chang-Duk 한국건설관리학회 2007 건설관리 : 한국건설관리학회 학회지 Vol.8 No.6
작업지연은 건설사업의 확실성을 저해하는 요소이다. 따라서 작업지연 원인에 대한 분류체계를 확립하고 관리항목을 도출하는 것은 건설사업의 경쟁력을 향상시킬 수 있는 요인이다. 하지만 분류별 작업지 연원인의 정량적 분석에 따른 중점관리 항목 도출에 대한 연구는 미흡하다. 따라서 본 연구에서는 설문조사와 인터뷰를 통한 공동주택 공사의 작업지연요소를 공종별로 도출하였다. 그 결과, 골조공사와 마감공사에서는 작업자수 부족이 전기설비에서는 작업자 능력이 그리고 기계설비에서는 선행 작업 미완료가 중점관리 대상으로 도출되었다. Work delay is one of the facts that make the reliability of construction projects decrease. Therefore, it is important to classify and prioritize the delay factors. This research analyzed key delay factors in apartment house construction through survey. The results of analysis are as follows. (1) Insufficient work force is the key delay factor in structural and finish work. (2) Improper craft of worker is the key delay factor in electrical work. (3) Incompletion of proceeding work is the key delay factor in mechanical work.
황련추출물-ceramide 복합물의 지방장벽 형성 조절을 통한 상피 염증 완화 효과
안상현,김기봉,Ahn, Sang Hyun,Kim, Ki Bong 대한한방소아과학회 2021 대한한방소아과학회지 Vol.35 No.3
Objective The purpose of this study was to confirm the effectiveness of coptidis rhizoma extract-ceramide complex on skin barrier, transepidermal water loss (TEWL) and pH reduction, and inflammation of the skin. Methods Coptidis rhizoma extract-ceramide complex was applied in 6-week-old Balb/C mice after dermatitis was induced. To confirm the skin condition changes, TEWL and pH were observed, and filaggrin in the stratum corneum of the skin was observed. Kallikrein-related peptidase (KLK) 7, Protease activated receptor (PAR)-2, Thymic stromal lymphopoietin (TSLP), and IL-4 were observed in the stratum corneum to confirm the changes in the inflammatory response. Results Filaggrin positive reaction was increased in the experiment group compared to the control group. TEWL and pH were lower in the experiment group compared to the control group. KLK7, PAR2, TSLP, and IL-4 positive responses were decreased in the experiment group compared to the control group. Conclusions It was confirmed that the coptidis rhizoma extract-ceramide complex can relieve the inflammatory response of atopic dermatitis by restoring the skin lipid barrier damage.