• Proceedings of the Korea Contents Association Conference
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• 2009.05a
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• pp.816-821
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• 2009

In this paper, I would like to talk about a step by step detailed information browsing which is founded on hierarchical structure for offering suitable information about the mass 3D data of a national treasure building to user as a standard of the visual distance. A step by step detailed information of the national treasure building of gigantic proportions offers a process of detailed information browsing which decided suitable hierarchical structure as considering of the preprocessing procedure which produces hierarchical structure and a visual distance of user. In the preprocessing procedure, 3D data is divided and controlled by optimized spacial structures. The relevance connection between the inner spacial surface is then examined and reconfigured in order to prevent holes or distortions. Finally, relative information data is created. In detailed information browsing, by examining the visual distance between model and user, then by browsing proper step of data, suitable level model data can be provided to the users in accordance with the position of observation.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2000.05a
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• pp.51-52
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• 2000

전기아연도금강판은 표면이 미려하고 희생방식력이 뛰어나기 때문에 주로 자동차와 가전, 건자재 등에 많이 사용된다. 현재 냉연 표면처리 제품들은 연속도금공정에 의해 생산되고 있으며 고전류밀도에 의한 고속생산과 도늠액 제조와 조성이 비교적 단순해야 하는 여러 가지 이유로 염산욕과 황산욕을 가장 많이 사용하고 있다. 최근에 신설된 당사의 전기도금공정은 수직형으로 황산욕에서 불용성 양극을 채용하여 아연을 전기도금하고 있다. 일반적으로 황산욕은 염산욕 대비 전기 전도성이 나빠 과전압이 크게 걸리므로 불용성 양극을 사용하여 극간 거리를 최소화할 필요가 있다. 그러나 $Ir0_2$가 코팅된 불용성 양극은 가격이 비싸기 때문에 극간 거리를 너무 짧게 하면 깡대에 의해 손상을 받을 수가 있어 극간 거리를 줄이는데 한제가 있다. 따리서 용액의 전도도들 증가시켜 과전합을 줄이기 위해서는 타사에서 현재 사용하고 있는 황산나트륨, 황산칼륨, 황산암모늄 등에 대한 검토가 필요하다. 전기전도 보조제들은 용액의 전기전도도 뿐만 아니라 도금층의 외관 및 미세구조에도 많은 영향을 주는 것으로 알려져 있다. 따라서 본 연구에서는 황산나트륨, 황산암모늄의 농도를 변화시켜 표면외관, 한계전류밀도, 미세구조, 우선배향성 등을 조사하여 최적의 물성을 갖는 아연 도금층을 얻기 위한 조건을 도출하고자 하였다. 전기아연도금용 소재로는 두께 0.8mm이고 크기가 $100{\times}120mm$인 중저탄소강 (0.02% C)을 사용하였으며 전처리 과정으로 탈지와 산세를 행하고 현장 도금액을 사용하여 다음과 같은 조건 하에서 아연도금을 행하였고 극간전합을 측정하였다. 도금 후 표면의 미세구조는 SEM을 사용하여 관찰하였으며 표면외관 특성을 분석하기 위해 광택도계(Tri- Microgloss-60-85)를 이용하여 입사각 $60^{\circ}$ 에서 광택도를 측정하였고, 색차계(Color Quest II Hunter Lab.)를 사용하여 백색도를 각각 측정하였다. 또한 X선 회절기를 이용하여 도금층의 우선 배향성을 분석하였다.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.02a
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• pp.308-308
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• 2012

현재 결정질 태양전지 제작에 있어 공정 단가 및 재료비 절감을 위해 실리콘 웨이퍼의 두께가 점점 얇아지는 추세이며, 이에 따른 장파장 영역 흡수 손실을 감소시키기 위한 방안으로 후면 패시베이션에 관한 연구가 활발히 진행되고 있다. 후면 패시베이션층으로는 SiO2, SiNx, a-Si:H, SiOxNy 등의 물질이 사용되고 있으며, 본 연구에서는 SiO2/SiNx/SiO2 (ONO)의 삼중막 구조를 패시베이션층으로 하여 SiNx 단일막 구조와의 열처리 온도에 따른 소수캐리어 수명(${\tau}eff$), 후면 재결합속도(Seff), 확산거리(LD) 등의 파라미터 변화를 비교하였다. 증착 직후와 $350^{\circ}C$에서의 Forming Gas Annealing (FGA), 그리고 $800^{\circ}C$의 고온에서의 fast firing 후의 각각의 파라미터 변화를 관찰하였다. 증착 직후 SiNx 단일막과 ONO 삼중막의 소수캐리어 수명은 각각 $108{\mu}s$와 $145{\mu}s$를 보였다. 후면 재결합속도는 65 cm/s와 44 cm/s를 보였으며, 확산거리는 각각 $560{\mu}m$와 $640{\mu}m$를 나타내었다. FGA와 firing 열처리 후 세 파마미터는 모두 향상된 값을 보였으며 최종 firing 처리 후 단일막과 삼중막의 소수캐리어 수명은 각각 $196{\mu}s$와 $212{\mu}s$를 보였다. 또한 후면 재결합속도는 28 cm/s와 24 cm/s를 보였으며, 확산거리는 각각 $750{\mu}m$와 $780{\mu}m$를 보여 ONO 삼중막 구조의 경우에서 보다 우수한 특성을 보였다. 본 실험을 통해 SiNx 단일막보다 ONO 패시베이션 구조에서의 열적안정성이 우수함을 확인하였으며, 또한 ONO 패시베이션 구조는 열적 안정성뿐 아니라 n-type 도핑을 위한 Back To Back (BTB) 도핑 공정 시 후면으로 의 도펀트 침투를 막는 차단 층으로서의 역할도 기대할 수 있다.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2003.05a
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• pp.72-75
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• 2003

In this research, we focused on the effects of the orifice internal flow such as cavitation and hydraulic flip. The breakup characteristics such as the breakup length and trajectory were measured by changing the orifice diameter (d), the orifice length/orifice diameter (L/d), the injection pressure and the shapes (sharp and round) of orifice entrance to provide a lot of conditions of the orifice internal flow. It is found that cavitation bubbles that occur inside the sharp-edged orifice make the liquid jet ejecting from the orifice turbulent. In the orifices (L/d = 5), the hydraulic flip phenomenon is shown when the injection pressure is high. In case cavitation occurs it breaks up more earlier than that in case of non-cavitation. In case hydraulic flip occurs, since the area of the liquid jet becomes small, the breakup length is also small as that in case of cavitation. But the liquid column trajectories have a similar tendency irrespective of cavitation.

• Journal of the Korea Society for Simulation
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• v.25 no.3
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• pp.53-63
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• 2016

We consider simulation study combining static and mobile decoys for survivability of a surface warship against torpedo attack. It is assumed that an enemy torpedo is a passive acoustic homing torpedo and detects a target within its maximum target detection range and search beam angle by computing signal excess via passive sonar equation, and a warship conducts an evasive maneuvering with deploying static and mobile decoys simultaneously to counteract a torpedo attack. Suggesting the four different decoy deployment plans to achieve the best plan, we analyze an effectiveness for a warship's survival probability through Monte Carlo simulation, given a certain experimental environment. Furthermore, changing the speed and the source level of decoys, the maximum torpedo detection range of warship, and the maximum target detection range of torpedo, we observe the corresponding survival probabilities, which can provide the operational capabilities of an underwater defense system.

• Korean Journal of Optics and Photonics
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• v.14 no.6
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• pp.613-622
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• 2003

The multi-configurative microscopic system for inspecting the wire-bonding of reed frame is designed. Rays refracted by objective lens group which is composed of common lens group of x2 and x6 are splitted by beam-splitter, and Rays through the central region and the boundary region of the object imaged at x2 and x6 through imaging lens groups, respectively. The depth of wire structure on the reed frame has about $\pm$3 mm, in order to observe by uniform magnification without the dependency on the variation of objective distance generated by the depth of wire structure on the reed frame, imaging lens groups should be moved on nonlinear locus like mechanically compensated zoom lenses. The nonlinear equations for zoom locus are derived by using the Gaussian bracket. Refraction powers and positions of each groups are numerically determined by solving the equations, and initial design data for each groups is obtained by using Seidel third order aberration theory. The optimization technique is finally utilized to obtain this microscopic system.

• Journal of the Korean Geotechnical Society
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• v.26 no.12
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• pp.51-60
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• 2010

Earth pressure due to gravity generally increases linearly with the depth, but the distribution of earth pressure due to surface load depends on the loading condition, the ground condition, and the boundary condition. In this study, the earth pressure on a rigid wall due to the vertical surface load was measured in experiments. Rigid wall was built in the model test box, and it was filled with homogeneous sandy ground (width 30 cm, height 88 cm, length 110 cm). Rigid wall was composed of 8 segments, which were tested on the two load cells. In the tests, we observed the distribution of the earth pressure on the rigid wall depending on the vertical surface load and it's location. According to the test results, the lateral earth pressure due to the vertical surface load showed its maximum value at a constant depth and decreased with the depth, to the negligible value at the critical depth. The critical depth and the depth at which lateral earth pressure reaches its maximum were not decided by the magnitude of the vertical surface load. They were dependant on the distance from the rigid wall.

• Journal of Dental Rehabilitation and Applied Science
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• v.36 no.2
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• pp.104-111
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• 2020

Purpose: The purpose of this study is comparing the efficiency of debris removal of passive ultrasonic irrigation depend on different protocols. Materials and Methods: Forty-eight mandibular premolars were randomly divided into 2 groups depend on vibration power (Weak and Strong, n = 24). And then two groups were subdivided into 3 groups depend on the number of times that PUI used (1, 2 and 3, n = 8). After standardization, teeth were split into two halves. On the wall of one half of root canal, three depressions were cut at 1, 3 and 5 mm from the apex and in the same way two depressions were cut on the other half of root canal at 2, 4 mm from the apex. Each depression was filled with mixture of dentine and NaOCl. After irrigation, images of the root canal wall were taken, and then the amount of remaining dentine debris was evaluated. Results: There was no significant difference between weak and strong power of vibration groups. Weak vibration groups did not show significant difference depend on the different number of times PUI used. But in the strong vibration groups, twice and three times used groups show better removal efficiency. Conclusion: The removal efficiency of dentine debris is not significantly different depend on the power of vibration. And multiple use of PUI could have better irrigating effects at the apical third area in the strong vibration group.

• Journal of Dental Rehabilitation and Applied Science
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• v.34 no.4
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• pp.262-269
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• 2018

Purpose: The purpose of this study was to evaluate the deformation of the complete denture artificial teeth arrangement after festooning over time. Materials and Methods: 10 wax dentures of equal teeth arrangement and equal gingival contour were used in this study. Festooning of the wax dentures were conducted and 3D model scans were conducted every 10 minutes for 120 minutes. Interdental transverse distances were measured with the scanned images. Statistical analyses were performed with SPSS Ver. 22. 0. Results: Interdental transverse distance between teeth varied from 0.0999 mm to 0.1787 mm. Mean rate of deformation showed statistically significant change between the 40 - 50 minute interval and 50 - 60 minute interval and between the 50 - 60 minute interval and 60 - 70 minute interval. No statistically significant change of the mean rate of deformation was observed later on. Conclusion: Monitoring of the interdental transverse distance for 120 minute after festooning have shown the deformation and displacment of the artificial teeth arrangement. From after the 60 - 70 minute interval after festooning, the mean deformation showed no statistically significant change of the mean rate of deformation was observed. Within the limitations of this in vitro study results suggest that the final occlusal adjustment in wax denture before complete denture curing should be proceeded at least 60 minutes later after festooning.

• Korean Journal of Optics and Photonics
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• v.18 no.4
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• pp.246-255
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• 2007

The floating image system (FIS) is a device to display input source in the space between fast surface of the display and an observer and it provides pseudo 3D depth to an observer when input source as real object or 2D image was displayed through the optical lens system in the FIS. The Advanced floating image system (AFIS) was designed to give more effective 3D depth than existing FIS by adding front and rear depth cues to the displayed stereogram, which it was used as input source. The magnitude of disparity and size of stereogram were strongly related each other and they have been optimized for presenting 3D depths in a non-optical lens systems. Thus, if they were used in optical lens system, they will have reduced or magnified parameters, leading to problem such as providing incorrect 3D depth cues to an observer. Although the size of stereogram and disparity were demagnified by total magnifying power of optical system, the viewing distance (VD) from the display to an observer and base distance (BD) for the gap between the eyes were fixed. For this reason, the quantity of disparity in displayed stereogram through the existing FIS has not kept the magnifying power to the total optical system. Therefore, we proposed the methods to provide correct 3D depth to an observer by compensating quantity of disparity in stereogram which was satisfied to keep total magnifying power of optical lenses system by AFIS. Consequently, the AFIS provides a good floating depth (pseudo 3D) with correct front and rear 3D depth cues to an observer.