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Development of 3-D Field Grid Generating Method for Viscous Flow Calculation around a Practical Hull Form (선체주위의 점성유동 계산을 위한 3차원 공간 격자계 생성방법)

  • Wu-Joan Kim;Do-Hyun Kim;Suak-Ho Van
    • Journal of the Society of Naval Architects of Korea
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    • v.36 no.1
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    • pp.70-81
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    • 1999
  • To predict the viscous boundary layers and wakes around a ship, the CFD techniques are commonly used. For the efficient application of CFD tools to practical hull farms, a 3-D field grid generating system is developed. The present grid generating system utilizes the solution of Poisson equation. Sorenson's method developed for 2-D is extended into 3-D to provide the forcing functions controling grid interval and orthogonality on hull surface, etc. The weighting function scheme is used for the discretization of the Poisson equation and the linear equations are solved by using MSIP salver. The trans-finite interpolation is also employed to assure the smooth transition into boundary surface grids. To rove the applicability, the field grid systems around a container ship and a VLCC with bow and stem bulb are illustrated, and the procedures for generating 3-D field grid system are explained.

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Development of a PC-based 3-D Seismic Visualization Software (PC 기반의 3차원 탄성파 자료 시각화 소프트웨어 개발 연구)

  • Kim, Hyeon-Gyu;Lee, Doo-Sung
    • Geophysics and Geophysical Exploration
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    • v.6 no.1
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    • pp.35-39
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    • 2003
  • A software to visualize and analyse 3-D seismic data is developed using OpenGL, one of the most popular 3-D graphic library, under the PC and Windows platform. The software can visualize the data as volume and slices, whose color distribution is specified by a special dialog box that can pick a color in RGB or HSV format. The dialog box can also designate opacity values so that several 3-D objects can be displayed superimposed each other. Horizon picking is implemented very easily with this software thanks to the guided picking method. The picked points from a horizon will compose a set of points, mesh, and a surface, which can be viewed and analysed in three dimensions.

The Vegetation of Mt. Geum Area in Namhae-Gun (남해군 금산지역 식생에 관한 연구)

  • 김인택;이지훈
    • Journal of Life Science
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    • v.13 no.5
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    • pp.740-745
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    • 2003
  • The vegetation of Mt. Geum in Namhae-gun Gyeongsangnam-do was investigated by the methodology of the ZM school, from February, 2000 to May, 2002. An actural vegetation map and vegetation table were constructed to understand the distribution of plant community in this area. The vegetation in this study area was classified into 10 communities (Pinus. densiflora, P. thunbergii, Quercus acutissima, Q. serrata, Q. variablis, Q. mongolica, Styrax ja-ponica, Corylopsis coreana, Zelkova serrata and Carpinus tschonoskii) and 1 afforestation (Chamaecyparis obtusa). According to the actual vegetation map, P. thunbergii forest, Q. serrata forest and Q. mongolica forest were found at the southern slope, northern slope and the center region of Mt. Geum, respectively. The forest of P. thunbergii was widely distributed in this area.

Hybrid Cryptosystem based on Diffie-Hellman over Elliptic Curve (타원 곡선 상의 Diffie-Hellman 기반 하이브리드 암호 시스템)

  • 정경숙;정태충
    • Journal of the Korea Society of Computer and Information
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    • v.8 no.4
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    • pp.104-110
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    • 2003
  • In this paper, we proposed hybrid cryptosystem of Diffie-Hellman base in Elliptic Curve, and explained for specific protocol design. The proposed system is efficient hybrid cryptosystems system that offer implicit key authentication about sender and receiver unlike existing hybrid system. This system increased safety generating session key using pseudo-random number generator by cryptographic. Because the system is hybrid system, it is more efficient in calculation amount aspect supplementing merit and fault of public key system and secret key system. Also, the system can not get right plaintext except receiver even if sender's secret key is revealed and impersonation attack is impossible. And the system offers security on known keys without influencing in safety of other session's cryptogram even if session key is exposed. And the system is provided safety about mutual entity authentication and replay attack.

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터빈계통의 축정렬 (I) : 원리와 방법

  • Hwang, Cheol-Ho;Kim, Jeong-Tae;Lee, Hyun;Lee, Byeong-Jun
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 1992.10a
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    • pp.71-76
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    • 1992
  • 축정렬이 불량한 경우 축진동이 과도하게 발생하여 출력이 감소하고 소음이 발생하며, 심한 경우 회전체의 파손과 같은 손실을 입을 수 있다. 특히 축 정렬불량으로 인한 진동은 교정이 안되는 것이 특징이므로 근본적으로 진동 을 해결하기 위해서는 축 정렬을 다시 시행해야 한다. 그러나 터빈은 다른 기계 구조물과 달리 분해 점검에 많은 시간과 경비가 요구되므로 축 정렬시 정확한 작업이 요구된다. 본 연구에서는 터빈계통의 축정렬을 수행하는 절차 와 방법에 대해서 검토하였다. 이를 위해 축정렬이 입력데이터로 쓰일 수 있 는 상태측정방법중 커플링 원주와 커플링 면 측정방법이 설명되었으며, 측정 값으로부터 축정렬을 수행하기 위해, 베어링의 이동량 계산과정과 쉼 가감량 의 계산방법을 기술하였다. 축정렬의 원리와 방법의 적용과정을 실제로 알아 보기 위해 평택화력 1,2호기에 대한 축정렬이 수행되었다. 1,2호기는 고압터 빈, 2단계의 저압터빈 및 발전기로 구성되어 있는 다축 시스템으로서, 제작 사측에서 요구하는 정렬 기준값을 감안하여 축정렬에 필요한 베어링 조정량 을 계산하였다. 계산과정은 기준로터로 지정된 저압터빈에서부터 축정렬상태 도를 작성하여 가면서 단계적으로 설명되었으며, 최종적으로 쉼의 가감량까 지를 보여줌으로서 축정렬과정을 완료하였다.

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A Study on the Journal Evaluation Policy of Korea Research Foundation (학술지 평가정책에 관한 고찰 -학술진흥재단의 학술지정책을 중심으로-)

  • 장덕현
    • Journal of Korean Library and Information Science Society
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    • v.35 no.1
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    • pp.359-376
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    • 2004
  • The role of scholarly journals in academic world is widely know and is recognized as the most important tool to improve the quality of scholarly communication. To do this, reasonable and legitimate evaluation methods are to be designed and to be applied. However, despite a lot of criticism regarding this issue, current journal evaluation policies have not drawn attention in related disciplines. In this regard, this paper attempts to shed light on some aspects related to the Korea Research Foundation's journal evaluation policy. Potential problems are particularly highlighted. It also addresses issues in using such data and tools in evaluating scholarly performance of researchers in academic institutions.

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Analysis on the Oceanic Circulation and Pollutant Transport near a Wolsung Nuclear Power Plant (월성원전주변의 해수유동 및 오염물 이동해석)

  • Park, Geon-Hyeong;Kim, Ki-Chul;Lee, Jung-Lyul;Suh, Kyung-Suk
    • Proceedings of the Korea Water Resources Association Conference
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    • 2011.05a
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    • pp.250-250
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    • 2011
  • 지정학적으로 3면이 바다로 접하고 있는 우리나라 해안가 주변의 원자력발전소는 관류형 냉각 방식(Once-through cooling System)을 채택하고 있기에, 이 계통을 통과한 냉각수는 주변해역으로 흘러들어가 주변 환경에 영향을 줄 수 있다. 또한 동해 주변 인접국들의 활발한 원자력 이용과 방사능 물질의 수송 등으로 인해 방사능 사고 위험이 증대됨에 따라 동해 원전 주변의 해양방사성물질 거동에 대한 필요성이 제기되고 있다. 이에 따라 동해의 해양환경을 조사 분석하여 해역에서의 오염 물질의 거동 파악이 중요하고, 산업시설 주변 연안의 오염물 이동 및 해석을 위해 오염물의 시 공간적으로 농도를 추정하는 것이 중요한 사항이다. 따라서 본 연구에서 수직 수평적으로 2차원 및 3차원화가 용이한 EFDC 모델을 사용하였다. 국립해양조사원에서 발간하는 DC103의 수치해도를 이용하여 모델영역은 동서방향으로 171km, 남북방향으로 235km로 설정하고, 격자간격은 $1km{\times}1km$의 정방향 격자를 사용하여 동해 월성 주변의 조위 시계열 검증 및 조화분석을 통한 검증을 실시한 결과 관측한 결과와 양호한 재현성을 나타내었다. 또한 국립수산과학원에서 제공되고 있는 년별 수온, 염분 자료 등의 해양환경과 지형적 특성을 고려하여 오염 물질의 이동 경로를 파악함으로써 사고시 피해를 줄이고자 한다.

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A Case Study of the Utilization of Cultural Property in Border Areas led by Local Residents - Focusing on the Horogoru Tong-il Balagi Festival in Wondang-ri, Jangnam-myeon, Yeoncheon-gun - (지역 주민주도를 통한 접경지역 문화유산 활용사례에 관한 연구 - 연천군 장남면 원당리 호로고루 통일바라기 축제를 중심으로 -)

  • LEE Sejin;PARK Kyujin;CHOI Jongtaik;LEE Donghae;KANG Sangsik
    • Korean Journal of Heritage: History & Science
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    • v.56 no.4
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    • pp.270-286
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    • 2023
  • This article is about the conservation and use cases of Horogoru, a Goguryeo site located in Wondang-ri, Jangnam-myeon, Yeoncheon-gun in Gyoenggi Province. After Horogoru was excavated, it was decided to build a park around it as a way to prevent damage, and also to plant sunflowers to symbolize the sun. Naming the park 'Tong-il Balagi Park', which refers to the wish for unification, local residents and other related organizations jointly opened the site. Afterwards, they looked for ways to utilize the location and park, and chose to hold the 'Tong-il Balagi Festival'. The festival is an event held under the leadership of local residents, which has the effect of promoting both conservation and cultural property, as well as generating economic benefits. In other words, the Yeoncheon-gun, Jangnam-myeon Tong-il Balagi Festival can be said to be an exemplary example of successfully overcoming various disadvantages associated with the border area near the ceasefire line through local residents' own utilization of cultural property.

An Essay on the Change of Jinju Sword Dance after being designated as an Important Intangible Cultural Asset (<진주검무> 중요무형문화재 지정 이후의 변화에 관한 소고)

  • Lee, Jong Sook
    • Korean Journal of Heritage: History & Science
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    • v.49 no.1
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    • pp.4-21
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    • 2016
  • The purpose of this study is to investigate changes of Jinju Sword Dance, characteristics of the changes, and the current condition of its preservation and succession after the designation as the important intangible cultural property no. 12 in January 16th, 1967. In other words, this study understands the situation which has established the present state of after changes over generations. As of now. the year of 2015, the 3 generation holders have been approved since 1967. In 1967, 8 members of $1^{st}$ generation holders were selected from gisaengs of Gwonbeon. However, the succession training was incomplete due to conflicts among the holders, the deaths of some holders, and economic activities of the individuals. As the need of a pivot for succession training and activities was rising, Seong, Gye-Ok was additionally approved as the $2^{nd}$ generation holder on June $21^{st}$, 1978. Seong, Gye-Ok who had never been a gisaeng had dramatically changed with a lot of new attempts. After the death of Seong, Gye-Ok in 2009, Kim, Tae-Yeon and Yu, Yeong-Hee were approved as the $3^{rd}$ generation holders in February, 2010. Based on the resources including the "Cultural Research Reports of Important Intangible Cultural Properties" in 1966 and videos up to 2014, the changes of the dance and surroundings are as follow. 1. The formation of musical accompaniment has been changed during the 3 generations. In the video of the $1^{st}$ generation(in 1970), the performance lasted about 15 minutes, whereas the performance lasted 25 minutes in the video of the $2^{nd}$ generation. Yumbuldoduri rhythm was considered as Ginyumbul(Sangryeongsan) and played more slowly. The original dance requiring only 15 rhythms was extended to 39 rhythms to provide longer performance time. In the $3^{rd}$ generation, the dance recovered 15 rhythms using the term Ginyumbul. The facts that Yumbul was played for 3 minutes in the $1^{st}$ generation but for 5 minutes in the 3rd generation shows that there was tendency pursuing the slowness from the $2^{nd}$ generation. 2. For the composition of the Dance, the performance included additional 20 rhythms of Ginyumbul and Ah(亞)-shaped formation from the $2^{nd}$ generation. From the $3^{rd}$ generation, the performance excluded the formation which had no traditional base. For the movement of the Dance, the bridge poses of Ggakjittegi and Bangsukdoli have been visibly inflexible. Also, the extention of time value in 1 beat led the Dance less vibrant. 3. At the designation as an important intangible cultural property (in 1967), the swords with rotatable necks were used, whereas the dancers had been using the swords with non-rotatable necks since late 1970s when the $2^{nd}$ generation holder began to used them. The swords in the "Research Reports" (in 1966) was pointy and semilunar, whereas the straight swords are being used currently. The use of the straight swords can be confirmed from the videos after 1970. 4. There is no change in wearing Jeonlib, Jeonbok, and Hansam, whereas the arrangement of Saekdong of Hansam was different from the arrangement shown in the "Research Reports". Also, dancers were considered to begin wearing the navy skirts when the swords with non-rotatable necks began to be used. Those results showed that has been actively changed for 50 years after the designation. The $2^{nd}$ generation holder, Seong, Gye-Ok, was the pivot of the changes. However, , which was already designated as an important intangible cultural property, is considered to be only a victim of the change experiment from the project to restore Gyobang culture in Jinju, and it is a priority to conduct studies with historical legitimacy. First of all, the slowing beat should be emphasized as the main fact to reduce both the liveliness and dynamic beauty of the Dance.

Community Analysis and Bological Water Quality Evaluation of Benthic Macroinvertebrate in Wangpi-cheon Watershed (왕피천 유역의 저서성 대형무척추동물 군집분석 및 생물학적 수질평가)

  • Park, Young-Jun;Jeon, Yong-Lak;Kim, Ki-Dong;Yoon, Hee-Nam;Nam, Sang-Ho
    • Korean Journal of Environment and Ecology
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    • v.27 no.3
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    • pp.327-343
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    • 2013
  • The aim of this study is to perform community analysis and biological assessment of water quality using benthic macroinvertebrate from Wangpi-cheon watershed which is defined as conservation areas of ecosystem and landscape by ministry of environment in Korea. Field survey of the study area was carried out 2 times from June to September in 2012. As a result of the field survey, total 155 species of benthic macroinvertebrates in 74 families, 15 orders, 7 classes and 5 phyla were collected. The findings of community analysis using the classified species and individuals showed relatively low DI(Dominant Index) value of 0.22 and very high value of average H'(Diversity index) as 4.24. And the analyzed results of SI(Similarity Index) according to habitat types using functional feeding groups showed higher values of 94.51% and 93.19% respectively to tributary and main stream after the designation of conservation areas of ecosystem and landscape. These results infer that various species and lots of individual are widely distributed at Wangpi-cheon watershed and stream ecosystem of the study area is healthy and well maintained after the designation of conservation areas. And also, the calculated EPT value was 62.9% as high enough to explain the cleanness of Wangpi-cheon watershed. We evaluated environmental condition and biological water quality by using ESB(Ecological Score of Benthic macroinvertebrate community) and KSI(Korean Saprobic Index). The average evaluated ESB shows very high value of 208.2, therefore Wangpi-cheon watershed is designated as 'First priority protection waters' area and the value of KSI is 0.32 which meets the saprobic water quality standard as 'First class'.