• Proceedings of the KSR Conference
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• 2007.11a
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• pp.658-670
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• 2007

Most railroad accidents are due to human errors. In particular, most of the causes of these accidents are faults of an engine driver, such as lack of signal confirmation, insecure braking, driving by guess or force of habit. This paper identifies a problem(s) by analyzing accidents for the past 10 years and also seeks a solution to train good engine drivers in order to prevent railroad accidents. In summary, what is needed are: 1) proper placement of various manpower, 2) proper training of engine drivers, 3) proper legislation for a 2-man on board system, and 4) proper reformation of personnel management.

• Journal of the Society of Naval Architects of Korea
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• v.31 no.1
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• pp.42-49
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• 1994

The purpose of CIM for shipbuilding should be focused on the efficient processing of information among design, process planning and scheduling activities. The most essential technology for shipbuilding CIM is the product model. This model should not only define a physical product "ship" but also a process "ship production". Major activity for ship production is assembly, which requires intensive use of the relationships among parts of ship structure. Other production information are painting area. shape. weight, etc. The fact that major ship structure is "stiffened-plate" type, which allows us to handle the plate thickness as non-geometric information for practical purpose. Therefore. the geometric model for ship product model should handle the relationship among parts(so called topology) efficiently. We find that a face oriented non manifold data structure can meet this requirement. We apply this non-manifold data structure to the ship compartmentation, structural design, and assembly.

• Journal of the Korean Institute of Traditional Landscape Architecture
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• v.33 no.1
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• pp.119-128
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• 2015

The purpose of this study was to look at the Jungeun-sasang(中隱思想) and garden of Bai Juyi in the perspective of landscape architecture and inquiry the meaning of Bai Juyi's construction activities, thought shown in his gardens, and how his construction method influenced later and the result is as follows. First, the 'Jungeun-sasang(中隱思想)' of Bai Juyi improved the Eunil-sasang(隱逸思想) and the birth of 'Jungeun-sasang(中隱思想)' became a clue to be developed up to the garden art. In addition, different from before that built gardens hiding in mountains, it prepared the turning point to build gardens in cities. Second, the space principle of 'paradise' shown in the garden of Bai Juyi was a means and principle to absorb the nature such as positioning rocks, formation of mounds, and positioning of flowers in the limited and small spaces different from previous gardens of splendid and magnificent. The garden became not only outer scene but also the 'Simwon(心園) that reflected the inside world. 12) Third, the gardening act and thought appeared in the poem of Bai Juyi were expressed in pictures and his own gardens as his poem was borrowed and quoted. As a result, Bai Juyi's literary view on the art and thought prepared the base in the popularity of literary gardens and forming of characteristic styles through practical activities that he managed his own gardens. Forth, Bai Juyi's level of Confucianism realization and delicate aesthetical consciousness gave meanings to the scene of gardens through the discovery of the fusion of mountains and creeks, ways of adding, and the aesthetical consciousness of Taihushi(太湖石)and influenced in the forming of garden culture later on.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.10
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• pp.6611-6617
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• 2015

The purpose of this study is to compare the marginal and internal fit of metal and zirconia coping which is fabricated by manual and CAD/CAM(Computer Aided Design/Computer Aided Manufacturing). The model is prepared with Urethane material and two abutment teeth are fabricated with a knife and chamfer margin. Silicon replica technique is used to measure the marginal fit of manually fabricated and the CAD/CAM coping. Internal fitting level is measured with a microscope and the image is captured with a CCD camera. The distance between abutment teeth and coping is measured with a callibrated image analyzer software; marginal opening (MO), marginal gap (MG), internal gap (IG) at maximum curvature area, axial gap (AG), and occlusal gap (OG). Two-way ANOVA test is applied to compare fabrication technique and to analysis of abutment pattern. In addition, one-way ANOVA and Scheffe's test is used to analyze each parameter of the test. The result shows that the fit is < $120{\mu}m$ except OG of CAD/CAM and MO of knife margin. The CAD/CAM fabricated coping showed higher fit level at chamfer margin. However, knife margin showed better fitness compared to chamfer margin at MG. AG showed the minimum dimension with a constant result (< $38{\mu}m$).

• Proceedings of the Korean Society for Agricultural Machinery Conference
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• 2017.04a
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• pp.10-10
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• 2017

우리나라 고추 재배는 ha당 총 노동투하시간 2,436 hr 중 수확작업시간은 954 hr으로 총 노동투하시간의 39.2%를 점유하고 있어 수확작업의 생력화를 위해 고추수확작업의 기계화가 절실히 필요하다. 고추 수확의 기계화를 위해 국내 T사에서 자주식 고추 수확기를 개발 중에 있다. 현재 고추를 기계로 채취하게 되면 많은 양의 줄기달린 고추가 유입되므로 수확 후 분리하는 작업에 있어 많은 인력과 시간이 소요되는 실정이다. 따라서 본 연구에서는 드럼 회전 타입의 2차 탈실부 요인시험 장치를 제작하여 드럼의 회전속도, 드럼과 급치 사이 간격에 대해 요인시험을 수행함으로써 자주식 고추수확기 2차 탈실부의 적정 작업조건을 파악함에 목적을 두었다. 탈실부 요인시험 장치는 급치가 부착된 3개의 드럼 형태의 탈실부와 이송벨트로 구성된다. 공시재료인 고추는 광주광역시 남구 승촌동 소재의 개인농가에서 Plastic 온실로 재배된 '천상' 품종을 사용하였다. 본 요인시험은 드럼의 회전속도(40, 70, 100, 130 rpm)와 드럼과 급치 사이 간격(2, 5, 10 mm)으로 요인을 설정하여 시험을 수행하였다. 시험은 각 요인 당 3반복으로 실시하였으며, 투입되는 시료는 줄기달린 고추를 3가지의 형태로 구분하여 제작하였다. 각 요인에 따라 고추의 탈실률, 손상률에 대해 통계프로그램인 SAS를 이용하여 분석하였다. 드럼의 회전속도에 따른 요인시험결과, 손상 대비 탈실률로 비교했을 때 회전속도 40 rpm에서 탈실률 47.69%, 손상률 8.33%로 성능이 가장 낮았으며, 회전속도 70 rpm에서 탈실률 63.89%, 손상률 12.96%로 성능이 가장 높았다. 드럼과 급치 사이의 간격에 따른 요인시험결과, 간격이 클수록 탈실률 및 손상률이 줄어드는 경향을 보였으며, 5 mm일 때 성능이 가장 높았다. 반복이 있는 이원배치법을 이용하여 분석한 결과, 고추 탈실률과 손상률은 드럼의 회전속도와 드럼과 급치 사이 간격 모두에서 유의차가 발생한다고 나타났다. 요인시험 결과를 종합적으로 고려해 보았을 때, 드럼 회전속도 70 rpm, 드럼과 급치 사이 간격 5 mm에서 가장 높은 성능을 보였다. 고추 탈실률이 낮고, 손상률이 높아 탈실장치로서의 기능에 어려움이 있을 것으로 보이므로 추후 급치 타입의 변경 등 탈실장치의 보완 및 개선이 필요할 것으로 판단된다.

• Korean Journal of Poultry Science
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• v.42 no.3
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• pp.257-265
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• 2015

Heat conditioning at an early age has been known to help chickens cope with heat stress later in life. The present study was conducted to determine the effects of heat conditioning at 5 days of age in broilers repeatedly exposed to high ambient temperature later in life. A total of 256 day-old Arbor Acre boiler chicks were housed in two identical rooms with a 23-h light/1-h dark cycle and provided with feed and water ad libitum. At 5 days of age, the birds in one room were exposed to $37^{\circ}C$ for 24 hours, while those in the other room served as controls. On day 21, half of the birds in each room were moved into the other room so that each room contained both control and heat-conditioned birds. After a 7-day adaptation period, the birds in one room were exposed to high ambient temperature ($21^{\circ}C{\rightarrow}31^{\circ}C$) for 3 days, whereas those in the other room were kept at normal temperature. The same 3-day exposure to high ambient temperature was repeated two weeks later. Hence, there were four treatment groups (CON+CON: control+control; CON+HS: control+high ambient temperature; HC+CON: heat conditioning+control; and HC+HS: heat conditioning+high ambient temperature). Repeated heat stress resulted in decreased feed intake, water intake, body weight gain, and spleen weight (p<0.05) and increased rectal temperature (p<0.05), mortality, and plasma corticosterone concentrations. The relative weight of the spleen was increased in the heat-conditioned group (p<0.05). Plasma biochemicals were also influenced by high temperature. Thus, no beneficial effects of heat conditioning at an early age were detected in broilers repeatedly exposed to high ambient temperature later in life.

• Journal of radiological science and technology
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• v.26 no.1
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• pp.83-89
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• 2003

The accurate measurement of the femoral anteversion is very important to the practice of orthopedic and osteotomy. It is measured by means of the axis of head and neck of the femur and the knee axis. At the present time, widely used computed tomography method of measuring anteversion on femoral necks of patients. Measurement by the manual method and image viewer of computed tomography to determine the anteversion of femoral head were carried out on both femurs. In September and October 2002, 5 patients 28 to 36 years of age were randomly selected from Seoul National University Hospital. The purpose of this paper was to introduce a new method to measure femoral anteversion angle utilizing PACS image viewer program in the MR imaging. Significant difference was observed between the right and left side the image viewer measurement of femoral anteversion. In conclusion, MR imaging very usefulness in the measured the angle of the femoral anteversion.

• Journal of the Korea Concrete Institute
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• v.13 no.5
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• pp.430-437
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• 2001

Recently, there have been increased much concerns about repair and rehabilitation works for aged concrete structures. It is in particular known that due to repeated overburden vehicles, there are significantly increasing number of aged concrete bridge slabs, which are strongly needed to construct and rehabilitate by innovative construction method. The objective of this research is to develop the new construction method of concrete slab in bridge superstructure, which can contribute to minimize a traffic congestion during repair and rehabilitation works of aged concrete slab, and can sufficiently assure the quality through the minimization of in-situ works at the site. I-beams with punch holes, which are substituted instead of main reinforcing steels in concrete slabs, can be manufactured in accordance with the specification in the factory, and be preassembled into the panel. After erecting the preassembled panels in the site, concrete will be poured into the slab panel. This research is to investigate mechanical properties of I-beam with punch holes itself, and then to investigate structural properties of assembled I-beam panels through static test, of which result can be utilized for the development of the new constructional method for concrete slab in bridge superstructure.

• Restorative Dentistry and Endodontics
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• v.35 no.3
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• pp.222-228
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• 2010

The purpose of this study was to compare mineral trioxide aggregate (MTA; Dentsply, Tulsa Dental, Tulsa, OK, USA), which is widely used as root-end filling material, with DiaRoot BioAggregate (DB; Innovative BioCaramix Inc, Vancouver, BC, Canada), newly developed product, by using MG63 osteoblast-like cells. MTA, DB, and Intermediate Restorative Material (IRM; Dentsply Caulk, Milford, DE, USA) were used for root-end filling material while tissue culture plastic was used for control group. Each material was mixed and, the mixtures were left to set for 24 hours. MG63 cells were seeded to each group and then they were cultured for attachment for 4 hours. Following the attachment of cells to the root-end filling material, early cellular response was observed. After another 12 hours'culture, the level of attachment between cells and material was observed and in order to identify the effect of each material to bone formation, transforming growth factor beta1 ($TGF{\beta}1$) and osteocalin (OC) were estimated by using enzyme-linked immunosorbent assay (ELISA), and the amount of alkaline phosphatase (ALP) was also measured. The data were analyzed using one-way ANOVA. As a result, only at OC and the number of cells which were attached to materials, there was no statistical difference between MTA and DB. At other items, there was statistically significant difference in all groups. Although DB has not shown exactly the same cellular response like that of MTA, the number of attached cells shows that biocompatibility of the material and OC indicates bone formation rate. Therefore, if DB is used for root end filling material, it is expected to lead to similar results to MTA.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.32 no.1
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• pp.1-6
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• 2022

In this research, a ring-shaped silicon carbide (SiC) single crystal manufactured using the PVT (Physical Vapor Transport) method was proposed to be applied to a SiC focus ring in semiconductor etching equipment. A cylindrical graphite structure was placed inside the graphite crucible to grow a ring-shaped SiC single crystal by the PVT method. SiC single crystal ring without crack was successfully obtained in case of using SiC single crystal wafer as a seed. A plasma etching process was performed to compare plasma resistance between the CVD-SiC focus ring and the PVT-SiC focus ring. The etch rate of ring materials in PVT-single crystal SiC focus ring was definitely lower than that of CVD-SiC focus ring, indicating better plasma resistance of PVT-SiC focus ring.