• Journal of Biosystems Engineering
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• 제43권3호
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• pp.247-254
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• 2018

Purpose: Although previous studies have performed on-farm evaluations for the control of airborne diseases such as foot-and-mouth disease (FMD) and influenza, disease control during the process of livestock and manure transportation has not been investigated thoroughly. The objective of this study is to predict common patterns of livestock-vehicle movement. Methods: Global positioning system (GPS) data collected during 2012 and 2013 from livestock vehicles on Jeju Island, South Korea, were analyzed. The GPS data included the coordinates of moving vehicles according to the time and date as well as the locations of livestock farms and manure-keeping sites. Data from 2012 were added to Esri software ArcGIS 10.1 and two approaches were adopted for predicting common vehicle-movement patterns, i.e., point-density and Euclidean-distance tools. To compare the predicted patterns with actual patterns for 2013, the same analysis was performed on the actual data. Results: When the manure-keeping sites and livestock farms were the same in both years, the common patterns of 2012 and 2013 were similar; however, differences arose in the patterns when these sites were changed. By using the point-density tool and Euclidean-distance tool, the average similarity between the predicted and actual common patterns for the three vehicles was 80% and 72%, respectively. Conclusions: From this analysis, we can determine common patterns of livestock vehicles using previous year's data. In the future, to obtain more accurate results and to devise a model for predicting patterns of vehicle movement, more dependent and independent variables will be considered.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2004년도 제22회 춘계학술대회논문집
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• pp.216-227
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• 2004

A new cavitating model by using bubble size distribution based on bubbles-mass has been proposed. Both liquid and vapor phases are treated with Eulerian framework as a mixture containing minute cavitating bubbles. In addition vapor phase consists of various sizes of vapor bubbles, which are distributed to classes based on their mass. The bubble number-density for each class was solved by considering the change of the bubble-mass due to phase change as well as generation of new bubbles due to heterogeneous nucleation. In this method, the bubble-mass is treated as an independent variable, and the other dependent variables are solved in spatial coordinates and bubble-mass coordinate. Firstly, we employed this method to calculate bubble nucleation and growth in stationary super-heated liquid nitrogen, and bubble collapse in stationary sub-cooled one. In the case of bubble growth in super-heated liquid, bubble number-density of the smallest class based on its mass is increased due to the nucleation. These new bubbles grow with time, and the bubbles shift to larger class. Therefore void fraction of each class is increased due to the growth in the whole class. On the other hand, in the case of bubble collapse in sub-cooled liquid, the existing bubbles are contracted, and then they shift to smaller class. It finally becomes extinct at the smallest one. Secondly, the present method is applied to a cavitating flow around NACA00l5 foil. Liquid nitrogen and liquid oxygen are employed as working fluids. Cavitation number, $\sigma$, is fixed at 0.15, inlet velocities are changed at 5, 10, 20 and 50m/s. Inlet temperatures are 90K in case of liquid nitrogen, and 90K and 1l0K in case of liquid oxygen. 110K of oxygen is corresponding to the 90K of nitrogen because of the same relative temperature to the critical one, $T_{r}$=$T/T_c^{+}$. Cavitating flow around the NACA0015 foils was properly analyzed by using bubble size distribution. Finally, the method is applied to a cavitating flow in an inducer of the LE-7A hydrogen turbo-pump. This inducer has 3 spiral foils. However, for simplicity, 2D calculation was carried out in an unrolled channel at 0.9R cross-section. The channel moves against the fluid at a peripheral velocity corresponding to the inducer revolutions. Total inlet pressure, $Pt_{in}$, is set at l00KPa, because cavitation is not generated at a design point, $Pt_{in}$=260KPa. The bubbles occur upstream of the foils and collapse between them. Cavitating flow in the inducer was successfully predicted by using the bubble size distribution.

• 한국운동역학회지
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• 제26권4호
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• pp.343-351
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• 2016

Objective: The purpose of this study was to help improve game performance and provide preliminary data to enhance the efficiency of the kick and stability of the support foot by comparing the kinematic characteristics of the repeated side kick (geodeupyeopchagi) in poomsaeKoryo between expert and non-expert groups. Method: The subjects were divided into 2 groups according to proficiency in Taekwondo, an expert group and a non-expert group (n = 7 in each group), to observe the repeated side-kick technique. Four video cameras were set at a speed of 60 frames/sec and exposure time of 1/500 sec to measure the kinematic factors of the 2 groups. The Kwon3D XPprogramas used to collect and analyze three-dimensional spatial coordinates. Ground reaction force data were obtained through a force plate with a 1.200-Hz frequency. An independent samplesttest was performed, and statistical significance was defined as .05. The SPSS 18.0 software was used to calculate the mean and standard deviation of the kinematic factors and to identify the difference between the experts and non-experts. Results: The angular displacement of the hip joint in both the expert and non-expert groups showed statistical significance on E1 and E4 of the left support foot and E5 of the right foot (p<.05). The angle displacement of the knee joint in both groups showed statistical significance on E4 of the left support foot, and E1 and E2 of the right foot (p<.05). The angular velocity of the lower leg in both groups showed no statistical significance on the left support foot but showed statistical significance on E2 and E6 of the right foot (p<.05). The angular velocity of the foot in both groups showed no statistical significance on the left support foot but showed statistical significance on E2 of the right foot (p<.05). The vertical ground reaction force in both groups showed statistical significance on E2 (p<.05). The center of pressure in all directions in both groups showed statistical significance (p<.5). Conclusion: While performing the repeated side kick (geodeupyeopchagi), the experts maintainedconsistency and stability of the angle of the support leg while the kick foot moved high and fast. On the other hand, the angle of the support foot of non-experts appeared inconsistent, and the kick foot was raised, relying on the support leg, resulting in unstable and inaccurate movement.

• 한국광학회지
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• 제32권5호
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• pp.220-229
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• 2021

눈부심 방지를 위한 확산판의 투과율과 연색지수 향상을 위한 양자점 필름의 농도가 고출력 직하형 백색 LED 조명의 광특성에 미치는 영향을 조사했다. 확산판의 투과율이 감소할 경우 조명의 휘도는 줄어들었고 색좌표, 상관색온도는 별다른 변화를 보이지 않았으며 연색지수는 약간 상승했다. 시야각에 따른 광특성의 편차는 거의 없었고 휘도 분포는 람버시안 분포에 가까웠다. 양자점 필름의 농도가 증가할 경우 스펙트럼 상 적색 성분이 늘어나면서 이 성분의 비중을 표현하는 색좌표 x가 증가했고 상관색온도는 약 6000 K에서 4000 K 부근으로 현저히 감소했다. 아울러 조명의 구조를 최적화하면 연색지수가 95까지 증가함을 확인했다. 이런 결과는 적절한 투과율의 확산판과 양자점 필름의 조합을 통해 눈부심이 없고 시야각에 따른 색편차가 거의 없으며 특히 색좌표의 가변이 가능한 고연색성의 조명 구현이 가능함을 보여준다.

• 한국ITS학회 논문지
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• 제18권5호
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• pp.34-48
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• 2019

본 연구는 우리나라 전체 도로 유형을 대상으로 빅데이터를 이용하여 안전성능함수(safety performance function, SPF)를 개발하고, 그것을 바탕으로 다양한 도로에 대한 안전등급을 평가함으로써 상대적으로 위험한 도로에 대한 대책을 수립할 수 있는 기초 정보를 제공하고자 하였다. 교통사고 자료를 국가표준 노드 및 링크 체계를 기반으로 전국의 도로에 매칭 하여 종속 변수로 활용하였으며, 독립변수로 링크 길이, 차로 수 등 기하구조 자료 및 한국교통연구원의 ViewT 교통량 자료, 그리고 사업용 차량에 장착된 운행기록계를 통한 위험운전행동 건수를 활용한 4개 시스템의 교통 빅데이터를 활용하여 연구를 진행하여 7개 도로 유형별 안전성능함수를 개발하고, 개발된 안전성능함수를 활용하여 도로유형별로 A, B, C, D 네 개의 안전등급을 평가하였다. 본 연구에서 사용한 방법론과 분석 결과를 토대로 우리나라의 위험도로를 선정하였다. 도출된 결과를 바탕으로 교통안전 개선사업의 대상을 선정하고 그에 따른 효과 등을 모니터링하고 계량화할 수 있을 것으로 기대된다.

• 대한치과교정학회지
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• 제32권2호통권91호
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• pp.79-89
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• 2002

본 연구의 목적은 일반두부방사선계측사진과 디지털두부방사선계측사진의 계측점 식별의 오차를 구하여 각각의 영상에서 오차의 특징을 살펴보고 재현성을 비교 평가하는 것이다. 연구 대상은 서울대학교병원 치과진료부 교정과에 내원한 교정 환자 중 18세에서 29세 사이의 성인 환자 중에서 일반두부방사선계측사진군과 디지털두부방사선계측사진군 각각 15명씩 30명을 무작위로 선택하여 연구 대상으로 하였으며 남녀의 구별이나 두개 안면 구조의 형태는 고려하지 않았다. 계측점은 동일인이 시간차를 두고 식별 하였다. 식별 후 각 계측점은 좌표 (x, y)로 표시하였으며, 처음 계측점을 식별한 두부방사선계측사진군을 T1으로, 1 주 후 동일 계측점을 재식별한 두부방사선계측사진군을 T2로, 1 달 후 동일계측점을 재식별한 두부방사선계측사진군을 T3로 분류하였다. 오차의 평균과 표준편차는 x좌표, y좌표로 구분하여 계산하였다. 초기 식별 1주 후 재식별시 오차는 T2-T1(x), T2-T1(y)로, 초기 측정 1달 후 재시별시 오차는 T3-T1(x), T3-T1(y)로 표시하였으며 일반두부방사선계측사진과 디지털두부방사선계측사진으로 각각 나누었다. 재현성의 평가를 위한 오차간의 통계학적인 검정은 independent t-test를 사용하였으며 다음과 같은 결론을 얻었다. 1. 디지털두부방사선계측사진이 일반두부방사선계측사진보다 일반적으로 오차의 평균 및 표준편차가 작았다. 2. 일반두부방사선계측사진의 오차와 디지털두부방사선계측사진의 오차가 통계학적으로 유의성 있는 차이를 보인 항목은 드물었다. 3.상의 향상을 통한 오차의 개선은 한계가 있었으며 상이 향상되더라도 각 계측점의 오차 의 경향은 크게 변하지 않았다.

• 미술이론과 현장
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• 제2호
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• pp.75-120
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• 2004

국내의 서양미술 관련 연구 장은 유럽과 미국 도시들과의 불가피한 거리 시간상의 차이로 인해 이미 '그곳'에서 '역사의 보편화 작업'이 종료된 사건들만을 재차 다룰 수밖에 없는 딜레마에 봉착해 있다. 이 같은 사실이 국내의 미술작용에 미치는 영향은 결코 단순하지 않다. 지극히 제한적으로만 원전의 생산과 그에 관련된 조건들에 접근이 허용됨으로써 연구가 피상적 수준에 머물 수밖에 없는 것이 그 한 예이다. 그럼에도 그 같은 피상적 연구들이 국내 미술 장의 어떤 정치, 권력적 문맥 안에서 상대적인 우위를 점함으로써 야기되어온 숱한 문제들이 또한 있다. 서양미술의 흐름과의 관계에서 그간 국내 미술이 보여주었던 과도한 연동성, 곧 '동화와 일치의 메커니즘'은 이 같은 원인이 초래한 결과다. 그럼에도, 국내의 서양미술사, 미술이론 영역의 연구들은 여전히 이 차이의 공간에 내재하는 컨텍스트를 간과함으로써, 결과적으로 서양미술의 '원전적' 정보를 매개하거나 확대 재생산하는 것에 지나지 않는 심각한 존재론적 한계를 노정해왔다. 또 국내의 서양미술사, 미술이론연구는 자신의 학문적 영역을 정당화하는 범주론과 영역주의 안에 거함으로써, 사이 공간에서 야기되는 복잡한 정치권력적 함의들을 독해해내는 데 어려움을 겪고 있다. 이와 같은 현실에서 우리는 서양미술사, 미술이론을 보다 반성적인 학문으로 이끌어야 하는데, 그러기 위해서는 학문으로서 결코 현실에 대해 어떠한 특권적 지위도 가지려해선 안 된다는 사실을 확인해야만 한다. 그러면서 지금 우리의 삶과 존재에 보다 예민하고 긴밀하게 관여하는 학문이기를 소망해야 할 것이다. 국내의 서양미술사, 미술이론연구 장이 다시 인력과 지원의 활발한 움직임들을 끌어들이고, 그들(그것들)과 함께 인간과 문명에 대한 공동성찰의 장으로 나서기 위해서는 객관성이라는 허구와 역사의 기계적이고 중립적인 독해로부터, 그리고 "토론장에서 마른 빵을 먹어치우는" 창백한 관습에서 사건들이 터지고 수습되는 뜨거운 현실로부터 새로이 출발할 수 있어야한다. 그리하여 충돌하는 두 개의 문화권역 사이에 끼어 분열을 경험하는 지식인 특유의 명석함으로 현실을 직시하고, 그 안에서 분별력 있는 선택과 판단에 필요한 조건들을 찾아내야 할 것이다. 예속과 자율의 변증법적인 관계 속에서 새로운 한국미술, 세계미술의 출범이 어떠해야 할 것인가를 끊임없이 제안하는 것, 그것이 서양미술사, 미술연구의 새로운 좌표가 되어야 할 것이다.

• 시큐리티연구
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• 제1호
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• pp.351-370
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• 1997

This study concerns possible measures to prevent separatists' terrorist acts against overseas Korean businessmen. Of late, many Korean enterprises are helping a number of foreign countries develop their economy, by building factories and manning regional offices in those countries. But recent development of terrorism especially against Korean businessmen is alarming. This report discusses the need for Korean enterprises heading overseas to prepare themselves with awareness of terrorism and possible protective measures against it, besides their routine pursuance of profits; and for the government and prospective enterprises to refrain from investing in those countries having active separatist movements. If an investment has become inevitable, a careful survey of the region in conflict should be conducted and self-protective measures should be put in place through security information exchange, emergency coordination and training of personnel, etc. This study will first review the past terrorist incidents involving employees of overseas Korean enterprises, and then will focuss on seeking effective measures on the basis of the reported incidents. In carrying out the study, related literature from both home and abroad have been used along with the preliminary materials reported and known on the Internet from recent incidents. 1. The separatist movements of minority groups Lately, minority separatist groups are increasingly resorting to terrorism to draw international attention with the political aim of gaining extended self rule or independence. 2. The state of terrorism against overseas Korean enterprises and Koreans Korean enterprises are now operating businesses, and having their own personnel stationed, in 85 countries including those in South East Asia and Middle East regions. In Sri Lanka, where a Korean enterprise recently became a target of terrorist bombing, there are 75 business firms from Korea and some 700 Korean employees are stationed as of August 1996. A total of 19 different terrorist incidents have taken place against Koreans abroad since 1990. 3. Terrorism preventive measures Terrorism preventive measures are discussed in two ways: measures by the government and by the enterprises. ${\blacktriangleleft}$ Measures by the government - Possible measures at governmental level can include collection and dissemination of terrorist activity information. Emphasis should be given to the information on North Korean activities in particular. ${\blacktriangleleft}$ Measures by individual enterprises - Organizational security plan must be established by individual enterprises and there should also be an increase of security budget. A reason for reluctant effort toward positive security plan is the perception that the security budget is not immediately linked to an increment of profit gain. Ensuring safety for overseas personnel is a fundamental obligation of an enterprise. Consultation and information exchange on security plan, and an emergency support system at a threat to security must be sought after and implemented. 4. Conclusion Today's terrorism varies widely depending on reasons and causes, and its means has become increasingly informationalized and scientific as well while its method is becoming more clandestine and violent. Terrorist organizations are increasingly aiming at enterprises for acquisition of budgets needed for their activities. Korean enterprises have extended their business realm to foreign countries since 1970, exposing themselves to terrorism. Enterprises and their employees, therefore, should establish their own security measures on the one hand while the government must provide general measures, on the other, for the protection of the life and property of Korean residents abroad from terrorist attacks. In this regard, set-up of a counter terrorist organization that coordinates the efforts of government authorities in various levels in planning and executing counter terrorist measures is desired. Since 1965, when the hostile North Korea began to step up its terrorist activities against South Koreans, there have been 7 different occasions of assassination attempt on South Korean presidents and some 500 cases of various kidnappings and attempted kidnappings. North Korea, nervous over the continued economic growth and social stabilization of South Korea, is now concentrating its efforts in the destruction and deterioration of the national power of South Korea for its earlier realization of reunification by force. The possibility of North Korean terrorism can be divided into external terrorist acts and internal terrorist acts depending on the nationality of the terrorists it uses. The external terrorist acts include those committed directly by North Korean agents in South Korea and abroad and those committed by dissident Koreans, hired Korean residents, or international professionals or independent international terrorists bought or instigated by North Korea. To protect the life and property of Korean enterprises and their employees abroad from the threat of terrorism, the government's administrative support and the organizational efforts of enterprises should necessarily be directed toward the planning of proper security measures and training of employees. Also, proper actions should be taken against possible terrorist acts toward Korean business employees abroad as long as there are ongoing hostilities from minority groups against their governments.