• 상하수도학회지
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• 제27권4호
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• pp.479-487
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• 2013

This study was to investigate characteristics for the pressure wave propagation and the maximum pressure near a rapid closure valve which was installed the end of multi piping network. The multi piping network consists of one inlet and three outlet with straight pipes. The diameter of the pipes including the valve was 100 mm, 80 mm, 80 mm respectively. The valve was rapidly closed with the instantaneous time which was 0.023s in the level for the water hammer. For the simulation, the influence of the pipe thickness and deformation due to pressure-wave-propagation was not considered. CFD was conducted under the following condition : the initial pressure was 1bar in the inlet and the mass flow rate was 7.83 kg/s in the outlet(the velocity in the pipe with 100 mm diameter was 1 m/s). As the valve have conditions that were status with and without fluid flow in the pipe after valve closing, the maximum pressure change and the frequency analysis were examined. As the results, the case that was status with fluid flow appeared the higher maximum pressure than another's, the maximum frequency band was about 10 ~ 11 Hz.

• International Journal of Knowledge Content Development & Technology
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• 제12권4호
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• pp.41-65
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• 2022

This study would understand the overall perception of our society about public libraries, analyzing the texts related to public libraries, utilizing the semantic connection network & sentiment analysis. For this purpose, this study collected data from the last five years with keywords, 'Library' and 'Lifelong Learning Center' from January 1, 2016 through November 30, 2020 through the blogs and cafés of major domestic portal sites. With the collected data, text mining, centrality of keywords, network structure, structural equipotentiality, and sensitivity analyses were conducted. As a result of the analysis, First, 'reading' and 'book' were identified as representative keywords that form the social perception of public libraries. Second, it turned out that there were keywords related to the use of the library and the untact service due to the recent spread of COVID-19. Third, in seeking a plan for the development of public libraries through the keywords drawn to have positive meanings, it is necessary to create continuous services that can form a new image of the library, breaking away from the existing fixed role and image of the library and increase the convenience of use. Fourth, facilities and facilities for library services were recognized from a neutral point of view. Fifth, the spread of infectious diseases, social distancing, and temporary closure and closure of libraries are negatively related to public libraries, and awareness of librarians has been identified as negative keywords.

• 대한두개안면성형외과학회지
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• 제10권2호
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• pp.127-130
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• 2009

Purpose: In an amputated auricle, a microvascular anastomosis is the best treatment of choice. But, the neartotally amputated auricle which is connected by very narrow tissue pedicle to the head, can survive by simple attachment without a microvascular anastomosis owing to the rich vascular network through the superficial temporal artery and posterior auricular artery. In cases of venous congestion resulting from a lack of vein anastomosis, medical leeches (Hirudo medicinalis) can solve the problem. We are reporting the case of a 6-year-old boy who had a neartotally amputated auricle with successful results by simple closure and medical leech treatment without a microvascular anastomosis. Methods: A 6-year-old male patient had an left auricular injury by an escalator accident. The left auricle was neartotally amputated from the temporal head with connection only by very narrow skin and subcutaneous pedicle (about 1 cm in width) at the helical root of upper and anterior part of auricle. Marginal bleeding from the avulsed auricle was noted and the arterial blood was supplied from a branch of upper auricular branch of the superficial temporal artery. The auricle was repaired by simple closure including cartilage and skin without any vascular anastomosis. After simple closure, the auricle showed good circulation with pink color. But on the 2nd day after the operation, there was a venous congestion with severe swelling, which resulted in a purplish colored auricle. The venous congestion disappeared after using medical leeches by the 5th day after the operation. Results: The repaired auricle showed aesthetically and functionally satisfactory result with normal development at the 9 months follow-up check after the operation. Conclusion: In cases of neartotally amputated auricles of children or crushing injury in which microsurgery is difficult, we can try simple closure with the use of medical leeches in treating a of venous congestion for a successful result.

• 한국측량학회:학술대회논문집
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• 한국측량학회 2007년도 춘계학술발표회 논문집
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• pp.7-10
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• 2007

The 1st order vertical network of Korea was adjusted in 1987 at first time. This is the second adjustment of the 1st order vertical network of Korea by National Geographic Information Institute. All the levelling data were acquired by digital level with invar staff. The number of 1st order level lines are 36, and 34 level lines comprise 11 circles of level network. Backward and forward error of a few level lines are larger than the regulations of NGII, Korea. Also, 3 circles of vertical network has circuit closure error that is exceed the regulation. As the result of 1st order vertical network adjustment, the reference standard error of the vertical network was $1.8mm/{\surd}km$.

• 한국안전학회지
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• 제35권2호
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• pp.84-93
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• 2020

In recent years, the scale of damage from disasters such as earthquakes and large-scale fires and floods that are occurring in Korea is increasing. Accordingly, interest in urban disaster prevention that combines living infrastructure such as roads and parks is boosting, and it is urgent to prepare measures to reduce the damage scale of local cities. The purpose of this study is to derive implications for disaster prevention measures in areas where disaster prevention safety of local cities is weak through examples of disaster prevention safety of local cities in case of disaster. To this end, this study analyzed the regional characteristics, current status, and disaster prevention problems of regional cities in Japan, and selected disaster-vulnerable areas, and considered the distance relationship between disaster prevention bases through road network analysis. In addition, road closure simulation using ArcGIS Network Analyst was conducted to analyze disaster prevention safety in the area. As a result, the situation of the village which has a high possibility of isolation by natural disasters was grasped in advance. Through this, the suburbs confirmed the necessity of supplementing the disaster prevention function through transportation maintenance such as forest roads, and it was found that the city needs to prepare a risk management system. Furthermore, this study suggests the need for research on areas with a high possibility of isolation, especially in areas where disaster prevention functions are weak in local cities in case of disaster, and shows countermeasures for disaster prevention measures and resident education.

• 트랜스-
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• 제13권
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• pp.91-116
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• 2022

웹 드라마는 인터넷 시대의 산물이라고 한다. 웹 드라마는 전통 텔레비전 드라마와는 다른 10대와 20대 젊은이들이 선호하는 일상적인 내용을 통해 인기를 끌고 주목을 받았다. 스낵 컬처로 인하여 많은 온라인 영상 플랫폼이 웹 드라마를 제작하기 시작했다. 웹 드라마는 스낵 컬처의 영향으로 서사가 종결되는 단막극 형태를 사용하고, 전통 텔레비전 드라마의 선형구조와 다른, 줄거리와 서사가 종결되는 단막극 형태의 영향을 받아 전통 텔레비전 드라마와는 다른 특성을 가진다. 본 연구는 한국에서 가장 큰 청춘 웹 드라마 제작회사 《플레이리스트 오리지널》의 청춘 웹 드라마를 통하여 서사가 종결되는 단막극 형태로 구성되는 청춘 웹 드라마의 특성을 살펴보고 청춘 웹 드라마의 서사가 종결되는 단막극 형태와 비선형 내러티브로 인해 나타나는 서사구조를 분석하고자 한다.

• 상하수도학회지
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• 제23권3호
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• pp.295-303
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• 2009

In the present study, a reliability analysis calculating the probability of system failure has been performed using cut set and results of numerical analysis for unsteady flow in pipe. Especially, the probability of system failure has been evaluated regarding the effect of valve closure which is a really important activity in operation of piping system. In spite of small amount of demand, it was found that fast valve closure can generate high probability of system failure. Furthermore, it was confirmed that surge tank can reduce the unsteady effects and probability of system failure in water distribution system. From the results, it was found that the unsteady flow has a significant effect on the probability of system failure Furthermore, it was able to find which pipe or cut set has high probability of system failure. So it could be used to determine which pipe or cut set has a priority of repair and replacement. Therefore, reliability analysis regarding unsteady flow has to be performed for the planning, designing, maintenance, and operation of piping system.

• 대한교통학회지
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• 제17권3호
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• pp.61-70
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• 1999

본 연구의 목적은 도시 가로망의 일부구간을 증설(폐쇄)하였을 경우 가로망의 통행시간이 증가(감소) 한다는 브라이스역설 이론이 실제 가로망상에서 구현되는지 입증하는데 있다. 사례연구를 위해 1999년2월 보수공사를 위해 3년간 폐쇄된 서울시 도심의 남산2호터널 구간을 선정하였고, 폐쇄시 서울시 전체가로망과 혼잡통행료 징수구간에 어떠한 영향을 미치는지를 분석하였다. 서울시의 교통혼잡관리를 위해 개발된 SECOMM모형을 효과 예측을 위해 활용하였고, 예측의 정확성을 검증하기 위해 이용자균형(UE: user equilibrium) 상태와 체계최적 (SO: system optimum) 상태에서의 총통행시간의 차이를 비교하였다. 또한 해당구간에 대한 서울시의 폐쇄전 후 모니터링 조사를 참조로 브라이스역설이 모형상에서 뿐만 아니라 실제가로상에서 구현되는지도 함께 비교 검증하였다. 분석결과 브라이스의 가정대로 가로망상의 통행수요가 고정되어 있을 경우 남산1, 3호터널의 혼잡통행료를 징수하는 상황에서 2호터널을 폐쇄하면 서울시 전체가로망의 속도가 21.95km/h에서 22.21km/h로 개선되어 브라이스역설 현상이 입증되었다. 반면, 혼잡통행료를 면제한 상황에서는 속도가 저하되는 것으로 나타나 브라이스역설 현상은 혼잡통행료 징수와 같은 주변 교통체계의 변화와 밀접하게 관련이 있는 것으로 나타났다. 한편, 가로상 통행수요가 가변적인 상황하에서는 서울시통행속도가 거의 변화가 없는 것으로 나타나 브라이스역설은 매우 제약적 환경에서 관측되어진다는 점을 확인하였다. 예측의 정확성에 대한 이론적 검증결과 UE의 평균통행시간이 SO의 평균통행시간에 비해 모두 크게 나타나서 결과가 이론적으로 정확함이 검증되었고 혼잡통행료 징수시 SO의 평균통행시간이 미 징수시의 SO보다 적게 나타나 남산 1, 3호터널의 혼잡통행료를 지속적으로 징수하는 것이 바람직한 것으로 평가되었다 한편, 서울시의 남산 2호터널 주변도로에 대한 사후모니터링 결과 평균속도가 폐쇄전 29.53km/h에서 폐쇄후 30.37km/h로 개선되어 브라이스역설 현상이 구현되고 있음을 현실적 관측치로 검증할 수 있었다.

• 한국시뮬레이션학회논문지
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• 제12권4호
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• pp.73-81
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• 2003

An Ad Hoc network is a dynamic multi-hop wireless network that is established by a group of mobile hosts on a shared wireless channel by virtue of their proximity to each other. Since wireless transmissions are locally broadcast in the region of the transmitting host, hosts that are in close proximity can hear each other and are said to be neighbors. The transitive closure of the neighborhood of all the hosts in the set of mobile hosts under consideration forms an Ad Hoc network. Thus, each host is potentially a router and it is possible to dynamically establish routes by chaining together a sequence of neighboring hosts from a source to a destination in the Ad Hoc network. In a network, various real-time services require the network to guarantee the Quality of Services provided to the receiver. End-to-end QoS can be provided most efficiently when each layer of the protocol stack translates the requirements of the application into layer classified requirements and satisfies them. In this study, a mechanism to guarantee the QoS in Ad Hoc networks with buffer nodes is proposed. They effectively prevent traffic congestion and yield better transmission rate. In this way QoS is enhanced.

• 한국지구물리탐사학회:학술대회논문집
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• 한국지구물리탐사학회 2003년도 Proceedings of the international symposium on the fusion technology
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• pp.115-121
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• 2003

Discrete joint network approach has widely been used to investigate the hydraulic behavior of jointed rock masses. In general, joints will undergo deformation due to stress redistribution induced by construction of underground openings, hence joint aperture is often assumed to have a probability distribution rather than to be a constant value. In real situations, however, it is more reasonable to take into account the effect of stress change on aperture values by calculating joint deformation. In this report, a mechanical process has been developed to determine the joint opening or closure based on a statistically generated joint network model. By performing numerical analyses, some significant results on the hydro-mechanical behavior of jointed rock masses have been summarized.