• 대한치과의사협회지
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• 제52권12호
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• pp.753-761
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• 2014

Purpose: This study was performed to examine distribution of accessory mandibular canal and its characteristics in mandibular third molars. Materials and methods: A total of 251 subjects (166 males and 85 females) having mandibular third molars bilaterally were included in the study. Cone-beam computed tomographic images were reviewed for bifid or trifid accessory mandibular canal. The prevalence of accessory mandibular canal was evaluated according to gender, side and its branching type. Proximity and crosssectional position of accessory mandibular canal to mandibular third molar was analyzed. Results: Accessory mandibular canals were found in 66 (26.3%) of 251 patients and 86 (17.1%) of 502 hemi-mandibles. Gender and sides showed no statistically significant differences in prevalence. Retromolar canal (46.1%) was the most common branching type. Proximity of accessory canal to mandibular third molars showed mean distance of 2.8 mm from third molar and a statistically significant difference was found among types of accessory canal. Dental canal was the closest to tooth among branching types and closer to tooth than main canal. On cross-sectional view, accessory canal was generally located on buccal side of mandibular third molar. Conclusion: Accessory mandibular canal was common and well detected with cone-beam computed tomography. Their localization is significant in all anesthetic and surgical procedures involving mandibular third molars.

• 농촌지도와개발
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• 제3권1호
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• pp.123-140
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• 1996

The main functions of university are research, teaching and social service. University would be developed only when all three functions are organically interacted. In this view, Korean universities have relatively weak in their social service function. On the other hand, Philippines universities are more developed than Korean universities. Taking the university to the people, rather than bringing the people to the university, is the goal of extension education in the Philippines university. The techniques of extension have bees consultation, demonstration, short courses, and correspondence of distance education. Especially in the Philippines, some agricultural universities have their own extension services besides those sponsored by the government. Since it is thought to be closest to the ideal system for bringing about agricultural development, and even though Philippines system has brought about many outstanding results, it would be very difficult to follow this pattern in Korea. Before we try to follow Philippines experience, we can not avoid the criticism on our preset extension education programs that they are usually poor organized, money oriented and routinizied. In order to improve the university`s extension function, universities should provide and develop various programs to meet the community`s educational demands positively and should, in the long run, open its facilities to the community to become a center of lifelong education.

• Molecules and Cells
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• 제21권1호
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• pp.135-140
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• 2006

Cytoplasmic male sterility (CMS) in plants, which is due to failure to produce functional pollen, is a maternally inherited trait. Specific nuclear genes that suppress CMS, termed fertility restorer (Rf) genes, have been identified in several plants. In this study, Rfl-inked molecular markers in pepper (Capsicum annuum L.) were detected by bulked segregant analysis of eight amplified fragment length polymorphisms (AFLPs). Only AFRF8 was successfully converted to a cleaved amplified polymorphic sequence (CAPS) marker. This was named AFRF8CAPS and genotype determination using it agreed with that obtained with the original AFRF8. A linkage map with a total size of 54.1 cM was constructed with AFRF8CAPS and the seven AFLP markers using the Kosambi function. The AFRF8CAPS marker was shown to be closest to Rf with a genetic distance of 1.8 cM. These markers will be useful for fast and reliable detection of restorer lines during $F_1$ hybrid seed production and breeding programs in pepper.

• 천문학회지
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• 제54권2호
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• pp.71-88
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• 2021

We use N-body/hydrodynamic simulations to study the evolution of the spin of a Milky Way-like galaxy through interactions. We perform a controlled experiment of co-planar galaxy-galaxy encounters and study the evolution of disk spins of interacting galaxies. Specifically, we consider cases where the late-type target galaxy encounters an equally massive companion galaxy, which has either a late or an early-type morphology, with a closest approach distance of about 50 kpc, in prograde or retrograde sense. By examining the time change of the circular velocity of the disk material of the target galaxy from each case, we find that the target galaxy tends to lose the spin through prograde collisions but hardly through retrograde collisions, regardless of the companion galaxy type. The decrease of the spin results mainly from the deflection of the orbit of the disk material by tidal disruption. Although there is some disk material which gains the circular velocity through hydrodynamic as well as gravitational interactions or by transferring material from the companion galaxy, it turns out that the amount of the material is generally insufficient to increase the overall galactic spin under the conditions we set. We find that the spin angular momentum of the target galaxy disk decreases by 15-20% after a prograde collision. We conclude that the accumulated effects of galaxy-galaxy interactions will play an important role in determining the total angular momentum of late-type galaxies.

• Steel and Composite Structures
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• 제38권1호
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• pp.79-86
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• 2021

Due to the complex geological conditions, a large number of high quality coal seams was buried in the western of China which cannot be mining in open-pit methods. The dynamic properties of that coal cannot be studied easily in real site for the complex working condition. The compound coal blocks made on the basis of the real situation were studied in the laboratory. The physical and mechanical properties of the compound coal blocks and the raw coal were contrasted by using the UCS tests. The results show that the compound coal blocks made by mixing coal powder, cement and water in proportion of 2.5:2:1 are the closest to that of standard raw coal. Then the propagation of strain waves and crushing effects on the coal were studied in the compound coal blocks by using the super dynamic strain test system and the numerical calculated method of ANSYS/LS-DYNA. The results show that the diameter of the crushing zone in the compound coal blocks was similar to that in the numerical results. The fractures distribution in laboratory tests also has a similar trend to the calculation results. The measured strain waves at the distance of 50 cm, 100 cm, and 150 cm from the center of the charge are mainly concerned at -1.0×104 με and have a similar trend as that in the numerical simulation.

• Nuclear Engineering and Technology
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• 제54권2호
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• pp.601-607
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• 2022

In recent years, monitoring of spent nuclear fuel inside dry cask storage has become an important area of national security. Muon tomography is a useful method for monitoring spent nuclear fuel because it uses high energy muons that penetrate deep into the target material and provides a 3-D structure of the inner materials. We designed a muon tomography system consisting of four 2-D position sensitive detector and characterized and optimized the system parameters. Each detector, measuring 200 × 200 cm², consists of a plastic scintillator, wavelength shifting (WLS) fibers and, SiPMs. The reconstructed image is obtained by extracting the intersection of the incoming and outgoing muon tracks using a Point-of-Closest-Approach (PoCA) algorithm. The Geant4 simulation was used to evaluate the performance of the muon tomography system and to optimize the design parameters including the pixel size of the muon detector, the field of view (FOV), and the distance between detectors. Based on the optimized design parameters, the spent fuel assemblies were modeled and the line profile was analyzed to conduct a feasibility study. Line profile analysis confirmed that muon tomography system can monitor nuclear spent fuel in dry storage container.

• 한국정보처리학회:학술대회논문집
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• 한국정보처리학회 2011년도 춘계학술발표대회
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• pp.158-159
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• 2011

Energy efficiency in wireless sensor networks (WSNs) is one significant factor that needs to be considered when making any designs or doing any enhancements on the communication protocol stack. In WSNs using traditional geographic routing, when a sensor node receives a data packet that needs to be transmitted to the sink, it will forward the packet to the neighbor node which is closest to the sink. The traditional geographic routing assumes that the link quality is always 100%. This may cause a bad result as per which we waste too many energy for retransmissions between the two nodes. Thus, the problem here is how to select such node as forwarder at most efficiently in the aspect of both energy consumption and the distance toward the destination. The better node we choose, the more energy we can conserve for the whole network. In this paper, we propose a next-hop forwarding selection metric, called Energy Consumption for Transmission (ECT), which can resolve the above problem in the best way.

• 천문학회보
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• 제46권1호
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• pp.56.3-57
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• 2021

We use N-body/hydrodynamic simulations to study the evolution of the spin of a Milky Way-like galaxy through interactions. We perform a controlled experiment of co-planner galaxy-galaxy encounters and study the evolution of disk spins of interacting galaxies. Specifically, we consider the cases where the late-type target galaxy encounters an equally massive companion galaxy, which has either a late or an early-type morphology, with the closest approach distance of about 50 kpc, in prograde or retrograde sense. By examining the time change of the circular velocity of the disk material of the target galaxy from each case, we find that the target galaxy tends to lose the spin through prograde collisions but hardly through retrograde collisions, regardless of the companion galaxy type. The decrease of the spin results mainly from the deflection of the orbit of the disk material by tidal disruption. It is found that the spin angular momentum of the disk of the target galaxy decreases by 15 - 20% after a prograde collision. We conclude that the accumulated effects of galaxy-galaxy interactions will play an important role in determining the angular momentum of late-type galaxies at current stage.

• 대한전자공학회논문지SP
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• 제49권3호
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• pp.67-73
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• 2012

지역적인 영상의 색변환이란 영상에서 특정 색을 포함하는 영역을 추정하고 이를 원하는 색으로 변환시키는 것이다. 기존방법에서는 색차만을 이용해서 바꾸고자 하는 색을 포함하는 영역을 추정하고 이를 변환하였다. 따라서 변환되는 색 주변에서 원하지 않는 색결점(color artifact)이 나타나게 되었다. 제안한 방법에서는 이러한 색결점을 줄이기 위해 컬러 카테고리 맵과 수정된 color influence map을 결합한 지역적인 색변환 방법을 제안하였다. 컬러 카테고리 맵은 모든 색을 사람의 인지를 기반으로 11가지의 컬러 카테고리로 나눈 것으로서, 컬러 정보만을 이용해서 먼저 바꾸고자하는 색을 포함한 입력 영상의 지역 영역을 대략적으로 추정한다. 다음으로, 수정된 color influence map을 이용하여 인접한 영역의 색을 고려한 색변환 정도를 계산한다. 기존의 방법처럼 단순히 동일한 가중치를 주는 색차보다는 밝기와 색도에 서로 다른 가중치를 주어 수정된 color influence map을 계산하였다. 마지막으로 각각의 컬러 카테고리 맵과 수정된 color influence map에 가중치를 결합하여 지역적인 영상의 색변환을 수행하였다. 실험을 통해 제안한 방법과 기존의 색변환 방법의 결과 영상을 비교해 보았으며, 제안한 방법에서 색결점이 적게 나타나는 것을 확인할 수 있다.

• 한국항해항만학회지
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• 제43권6호
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• pp.377-383
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• 2019

항해 중인 함정은 늘 충돌 가능성이 존재하지만 충돌회피를 위한 명확한 기동지침은 없고 함교 당직사관의 직관적 판단에 의존하는 경향이 있다. 본 연구에서는 항해 중인 함정이 방위끌림이 없는 장애물을 조우하는 상황에서 함교 당직사관을 대상으로 언제 어떻게 충돌을 회피하는지 설문조사를 실시하였다. 설문 결과를 활용하여 방위끌림이 없는 장애물 조우 상황, 주·야간 충돌 회피 방법을 분석하였다. 조함이 까다로운 지역은 평택, 목포 순이었고, 주로 협수로 내에서 발생하였다. 빈도는 4시간 항해 시 평균 1회 정도로 나타났으며, 1:1 조우 상황보다 다수 선박 조우가 많았다. 충돌침로 확인 시 전자해도보다 육안 확인 결과를 더 신뢰하였고, 충돌회피 고려 요소로 최단 접근거리, 최단 접근시간을 우선시하였다. 피항의무선과 침로유지선의 충돌회피 기동상 특별한 차이는 없었지만 주·야간 시 최단 접근거리의 차이는 존재했다. 충돌회피 시 대부분의 항해사들은 변침·변속을 함께 사용하는 것을 선호하며 타각 10~15°, 변속 ±5knots, 변침침로는 타함 함미 정방향에서 함미 가중치를 두었다. 이러한 결과들은 승조원들에게 부임 함정의 충돌 회피 기준을 제공하는데 도움이 될 것이며 나아가 AI, 빅데이터 기반의 무인함정 충돌회피 알고리즘 개발에도 적용될 것이다.