• 한국재료학회지
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• 제24권5호
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• pp.236-242
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• 2014

Fabrication of reaction-bonded $Al_2O_3$ (RBAO) ceramics using Al-Zn-Mg alloy powder was studied in order to improve traditional RBAO ceramic processing using Al powder. The influence on reaction-bonding and microstructure, as well as on physical and mechanical properties, of the particulate characteristics of the $Al_2O_3$-Al alloy powder mixtures after milling, was revealed. Variation of the particulate characteristics of this $Al_2O_3$-Al alloy powder mixture with milling time was reported previously. To start, the $Al_2O_3$-Al alloy powder mixture was milled, reaction-bonded, post-sintered, and characterized. During reaction-bonding of the $Al_2O_3$-Al alloy powder mixture compacts, oxidation of the Al alloy took place in two stages, that is, there was solid- and liquid-state oxidation of the Al alloy. The solid-state oxidation exhibited strong dependence on the density of surface defects on the Al-alloy particles formed during milling. Higher milling efficiency resulted in less participation of the Al alloy in reaction-bonding. This was because of its consumption by chemical reactions during milling, and subsequent powder handling, and could be rather harmful in the case of over-milling. In contrast to very little dependence of oxidation of the Al alloy on its particle size after milling, the relative density, microstructure, and flexural strength were strongly dependent on particle size after milling (i.e., on milling efficiency). The relative density and 4-point flexural strength of the RBAO ceramics in this study were ~98% and ~365 MPa, respectively, after post-sintering at $1,600^{\circ}C$.

• 경영정보학연구
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• 제10권1호
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• pp.115-133
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• 2008

3자 물류 업계는 주로 화주를 대신하여 화물을 출발지에서 도착지까지 전달해주는 업무를 담당하고 있으며, 이를 위해서는 출발지와 도착지간의 운송 수단, 출발/도착 스케줄, 그리고 운임 등에 대한 정보를 필요로 한다. 또한 복합운송은 다양한 수송수단을 서로 조화롭게 통제하여 마치 하나의 수송수단을 이용하는 것처럼 자연스럽게 운영되어야 하는데, 이를 위해서는 스케줄 정보 수집과 이를 통해 가능한 수송경로를 생성할 수 있는 시스템을 구축할 필요가 있다. 하지만 현재 물류업체에서는 체계적인 시스템의 부재로 인해 충분하고 객관적인 정보를 바탕으로 서비스를 제공하지 못하고 있다. 대부분 담당자의 경험을 통하여 수작업으로 수송경로를 계획하고 있어, 거래량 및 물량이 늘어날수록 수작업에 의한 작업은 한계를 보이고 있다. 복합운송에서 최적 수송경로 생성과 선정을 어렵게 하는 이유는 크게 두 가지로 볼 수 있다. 첫째는 수송경로를 선정하기 위한 운송수단 별 스케줄 데이터 확보의 어려움이다. 두 번째는 수많은 스케줄 자료를 바탕으로 가능한 수송경로를 생성하고, 이들 중 고객의 요구에 가장 적합한 경로를 찾아내는 방법 개발에 대한 어려움이다. 이에 본 연구에서는 웹을 통해 제공되고 있는 스케줄 정보를 능동적으로 탐색 및 식별하여 실시간으로 수집할 수 있는 방법과 복합수송 서비스를 제공하는 물류업체의 핵심적인 업무인 수송경로 생성과 선정을 지원하는 지능형 복합운송 경로 계획시스템을 개발하고자 한다.

• 디자인학연구
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• 제19권5호
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• pp.351-362
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• 2006

현대 대도심 지하철은 밀폐된 공간으로 노선에 따라 다수의 역이 연결되어 있어 길찾기의 문제의 발생 빈도가 높은 것으로 알려져 있다. 따라서 이용자가 자신의 위치를 인지할 수 있도록 장소적 정보를 최대한 표현하는 시각적 장소지시단서(visual cue)가 제공되어야 할 필요성이 제기되고 있다. 본 연구는 대중교통수단으로서의 지하철 사용이 늘어감에 따라 길찾기 관련 문제들에 대한 관심이 증가하는 상황에서 서울, 동경, 타이페이 주요 지하철역의 장소지시적 단서로서 역할하는 환경디자인 사례 및 사용된 디자인 기법을 조사 분석함으로써 이용자를 위한 길찾기 지원 디자인 가이드라인 도출에 기여하는 목적을 가진다. 이론연구 결과, 시각적 장소지시단서의 유형으로 유도표식, 구역차별화, 랜드마크의 방법이 도출되었고 사례조사를 통하여 유도표식에서 노선색선의 상하배열, 양면배열, 변형 그래픽 기법이, 구역차별화에서는 벽면과 바닥패턴, 기둥과, 벽면의 강조색, 마감 재료 사용에 의한 차별화 기법이, 그리고 랜드마크에서는 수퍼그래픽, 상징물, 예술장식, 장식조명 등에 의한 기법들이 도출되었다. 서울 조사대상역의 경우, 연결노선의 색을 이용한 유도 표식이 가장 적극적으로 사용되고 있었으며 바닥패턴이나 강조색을 이용한 벽면과 기둥에 의한 구역차별화도 적극 도입하고 있었다. 또한 호돌이, 훈민정음과 같은 장소의 이해를 돕는 랜드마크적 요소도 적극 활용되고 있었다. 동경 조사대상역의 경우, 유도표식에 의존하기 보다는 구역 차별화의 방법을 적극 활용하는 것으로 나타났는데 이는 공간구조와 지시내용의 복잡성 때문인 것으로 해석된다. 타이페이시 조사대상역의 경우, 전반적으로 단순하며 통일된 이미지로서 장소지시는 최소한의 표식선이나 랜드마크에 의존하고 있었다. 특히 구역차별화의 사례가 미약하였는데 이는 대부분 역이 광장형의 오픈 스페이스로서 개방된 시야가 확보되기 때문인 것으로 해석된다. 본 연구의 결과는 향후 다양한 검증을 통하여 보다 정확한 길찾기 지원적 측면의 환경디자인 가이드라인 제시로 이어져야 할 것이다.

• Archives of Pharmacal Research
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• 제28권9호
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• pp.995-1001
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• 2005

Morphine-induced analgesia has been shown to be antagonized by ginseng total saponins (GTS), which also inhibit the development of analgesic tolerance to and physical dependence on morphine. GTS is involved in both of these processes by inhibiting morphine-6-dehydrogenase, which catalyzes the synthesis of morphinone from morphine, and by increasing the level of hepatic glutathione, which participates in the toxicity response. Thus, the dual actions of ginseng are associated with the detoxification of morphine. In addition, the inhibitory or facilitated effects of GTS on electrically evoked contractions in guinea pig ileum (I-L-receptors) and mouse vas deferens $(\delta-receptors)$ are not mediated through opioid receptors, suggesting the involvement of non-opioid mechanisms. GTS also attenuates hyperactivity, reverse tolerance (behavioral sensitization), and conditioned place preference induced by psychotropic agents, such as methamphetamine, cocaine, and morphine. These effects of GTS may be attributed to complex pharmacological actions between dopamine receptors and a serotonergic/adenosine $A_{2A}1\delta-opioid$ receptor complex. Ginsenosides also attenuate the morphine-induced cAMP signaling pathway. Together, the results suggest that GTS may be useful in the prevention and therapy of the behavioral side effects induced by psychotropic agents.

• 근관절건강학회지
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• 제27권3호
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• pp.219-228
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• 2020

Purpose: This study was a comparative analysis of stroke-related factors between recurrent patients and non-recurrent patients. Methods: A retrospective cohort study design was used, and data were collected from March 2020 to April 2020 using electronic medical records. 244 patients (221 first-timers and 23 recurrent) were included in this study. Results: The stroke recurrence rate in 5 years was 9.4%, the readmission rate was 39.3%, and the mortality rate was 2.0%. The number of patients hospitalized for stroke was greater among men than among women. Of the patients, 60.7% had an underlying disease. With regard to daily life abilities, over 70% of participants needed more than moderate dependence and about 40% of participants had more than mild cognitive impairment. More than 50% were moved to wheelchairs or stretcher cars. The difference in the stroke readmission rate between recurrent and non-recurrent patients was statistically significant. Conclusions: Based on our findings, a program to prevent recurrence of stroke should be developed to considering age, ability of daily living, place of discharge, gait ability at discharge, and place of discharge.

• 천문학회보
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• 제40권2호
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• pp.45.3-46
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• 2015

Space weathering agents such as micrometeoroids and solar wind particles continuously age the uppermost regolith of the lunar surface by comminuting as well as darkening and reddening. Among several maturity indices, we investigate median grain size () and optical maturity (OMAT) of the crater rim walls. Crater rim wall is the most immature place among the impact crater features because the vertical mixing process by mass-movement can enhance the gardening of regolith and the supply of immature materials in the deeper layer to the surface. More than 140 simple and complex craters were considered. Both and OMAT values of the inner rim wall initially increase as the crater size increases until ~10-20 km, then decrease. This transition crater size happens to correspond to the transition diameter from simple to complex craters. For larger craters, i.e., complex craters, it is clear that the inner rim wall of the craters formed in recent eras tend to remain fresh and become mature along with time. For the simple crater case, smaller craters are more mature, which is opposite to the case of complex craters. This is thought to be because smaller craters become flattened more quickly, thus have smaller vertical mixing in the regolith due to mass-movement. We will also discuss on the maturity indices of the crater rim walls at high latitudes as a function of the position angle to see the latitude dependence of the space weathering process.

• 한국의학물리학회지:의학물리
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• 제6권2호
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• pp.29-34
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• 1995

쐐기인자는 중심축선상의 어느 특정 깊이에서 측정한 흡수선량으로써 쐐기가 제거된 선량과 쐐기가 부착된 선량의 비로써 정의된다. 본 연구에서는 조사야의 크기별 쐐기인자의 의존성을 살펴보았다. 쐐기인자들은 Varian Clinac1800의 6MV와 15MV 광자선과 Philips SL75/5 의 5MV광자선의 쐐기에 대하여 여러 조사야에 따라 구하였다. 특정 조사야 (10cmx10cm) 에서 구한 단일 쐐기인자를 모든 조사야에 적용시키는 것은 타당치가 않다. 두꺼운 쐐기일 경우 특히 SL75/5 의 5MV 광자선에서 autowedge 의 30cmx30cm 조사야 일 때 오차가 중요하였다(6.6%). 따라서 이러한 쐐기의 치료선량을 계산할 때는 조사야 크기에 따른 쐐기인자를 적용하여야 한다.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2005년도 ICCAS
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• pp.834-837
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• 2005

In this paper, we describe the method of non-invasive blood pressure measurement using pulse wave transit time(PWTT). PWTT is a new parameter involved with a vascular that can indicate the change of BP. PWTT is measured by continuous monitoring of ECG and pulse wave. No additional sensors or modules are required. In many cases, the change of PWTT correlates with the change of BP. We measure pulse wave using the photo plethysmograph(PPG) sensor in an earlobe and we measure ECG using the ECG monitoring device our made in the chest. The measurement device for detecting pulse wave consists of infrared LED for transmitted light illumination, pin photodiode as light detector, amplifier and filter. We composed 0.5Hz high pass, 60Hz notch and 10Hz low pass filter. ECG measurement device consists of multiplexer, amplifier, filter, micro-controller and RF module. After amplification and filtering, ECG signal and pulse wave is fed through micro-controller. We performed the initial work towards the development of ambulatory BP monitoring system using PWTT. An earlobe is suitable place to measure PPG signal without the restraint in daily work. From the results, we can know that the dependence of PWTT on BP is almost linear and it is possible to monitoring an individual BP continuously after the individual calibration.

• 한국항공우주법학회:학술대회논문집
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• 한국항공우주법학회 2008년도 제40회 국제학술발표대회
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• pp.165-182
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• 2008

The purpose of this study is to review the changes in the aviation safety management system, how that system has evolved and what forces caused these changes to take place. Also included is an examination of the development process of the aviation safety management system in view of the new institutionalism, identifying the patterns of change. Based on the results of this study, I propose policy methods to design a desirable civil aviation safety system with a view toward raising the safety standards in the Korean civil aviation community. The major analysis variables are as follows: first, aviation accidents caused by external factors and international standards as independent variables; second, environmental changes and political processes affecting aviation safety management system as major mediating variables; and third, the aviation safety management legal system, the aviation safety management organizations and an expert participation system as dependent variables. The institutional changes and continuance of the aviation safety management system show that when specific circumstances arise, the continuance lasts depending on the path dependency, and in a certain circumstance, when immanent changing factors reach a critical point, the system suddenly changes by a punctuated equilibrium, which are all included in this study.

• 한국세라믹학회지
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• 제45권2호
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• pp.90-93
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• 2008

The oxygen gas behavior in PDP (plasma Display Panel) glass melts doped with sulfate ($SO_4^{-2}$) or blast furnace slag (BFS, $S^{2-}$) or both by means of yttria-stabilized zirconia (YSZ) electrodes was observed after the first fining. The temperature dependence of oxygen equilibrium pressure ($P_{O2}$) in each melt showed typical behavior, namely $P_{O2}$ decreased as temperature decreased. This suggests that an oxidation of $S^{4+}$ to $S^{6+}$ took place. However, the $P_{O2}$-value at constant temperature increased in the following order: BFS$P_{O2}$ of the melt doped with sulfate+BFS was much lower than that of the melt with only sulfate, although only 10% of sulfur was added by the BFS. This behavior can be explained by the redox reaction between sulfide ions in the BFS and dissolved oxygen ions in the melt during the first fining.