• Journal of the Earthquake Engineering Society of Korea
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• v.14 no.2
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• pp.67-74
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• 2010

To a series of vibration records obtained from experimental modal testing using a fixed hammer and roving accelerometers for greenhouse arch structures, modal parameters such as natural frequencies, damping ratios and mode shapes are extracted by applying the two most advanced system identification methods in the frequency-domain up to now, so-called PolyMAX and FDD. The former involves both input and output data, while the latter utilizes only the output data. The possibility of determining the static buckling load, detecting damages, etc., for very slender steel-pipe arches by means of a non-destructive testing method based on vibration measurements is primarily investigated. The extracted modal parameters generally correlated well with those obtained using finite element analysis, demonstrating promising results for further on-going research.

• Journal of the korean academy of Pediatric Dentistry
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• v.41 no.1
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• pp.54-63
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• 2014

Transposition is a unique and extreme form of ectopic eruption where a tooth develops and erupts in a position, normally occupied by an adjacent tooth. Generally, three treatment options are available when the maxillary canine and first premolar are transposed. In the first treatment option, the transposed position of the teeth can be maintained such that the first premolar is moved to the position of the canine. Second, extraction of the maxillary first premolar can be considered. Third, the position of the transposed teeth can be corrected such that their normal positions in the arch are restored. Factors that should be considered in treatment modality decision include function, occlusion, periodontal support, treatment time, patient cooperation, and esthetic demands. This report describes cases of maxillary canine-premolar transposition treated with each of the three aforementioned treatment options. In the first case, transposed teeth were arranged in their transposed position. The second case was an extraction case. In the third case, orthodontic treatment and surgical repositioning were conducted.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.11a
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• pp.5-8
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• 2008

In this dissertation, experimental research was carried out to study the hysteretic behavior of reinforced high-strength concrete beam-column joints designed by high performance techniques, such as application of high-strength concrete, reducing of joint regions damage, moving of beam plastic hinge, advanced reinforcing detailings and High Ductile Fiber-Reinforced Mortar.(HDFRM) Specimens(HJCI), designed by the development of earthquake-resistant performance, moving of beam plastic hinge, and new design approach, were attained the moving of beam plastic hinge and developed significantly earthquake-resistant performance of such joints. Specimens(HJRP), designed with HDFRM, were indicated more stable hysteresis behavior, high load carrying capacity, and distributed crack pattern of specimens HJRP when compared to the control specimen.

• Journal of the Korean Ceramic Society
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• v.40 no.8
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• pp.784-790
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• 2003

Present investigation shows the analysis results for ceramic reinforced metal matrix composite under uniaxial transverse tensile loading. The resulting deformation, the projected damage type, and stress-strain behavior were computed depending on microstructure details such as the type of periodic reinforcement array, and the type of interface bonding. A two-dimensional finite element analysis was conducted based on the unit-cell of square, hexagonal, or diagonal periodic away For composite with strong interface bonding, the transverse stress vs. strain curve was generally increased with the increase of the ceramic volume fraction. For the composite with weakly bonded interface, however, the transverse stress vs. strain curve was reduced against the ceramic volume fraction. The decrease was caused by the interface debonding-induced stiffness reduction of the composite. For the composite of weakly bonded interface, the relative reduction rate in the final limit stress for hexagonal array was larger than that for square array. Outcome of the present study was compared favorably with the published literature data.

• Proceedings of the Korean Vacuum Society Conference
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• 1999.07a
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• pp.80-80
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• 1999

플라즈마 디스플레이 패널(PDP)의 공정을 간단히 하기 위하여 포토레지스트, ITO, 격벽재료를 Ar+ laser(λ-514 nm, CW)와 Nd:YAG laser(λ=532, 266nm, pulse)로 직접 패터닝 하였다. 레이저에 의한 포토레지스트의 패턴결과, 아르곤 이온 레이저의 포토레지스트 가공의 반응 메카니즘은 레이저 빔의 열에 의한 시료 표면의 국부적인 온도상승에 의한 용융작용이며, 그 결과 식각 후 형성된 패턴의 단면 모양도 레이저빔의 profile과 같은 가우시안 형태를 나타낸다. Nd:YAG 레이저의 4고조파(532nm)를 이용한 경우 200$\mu\textrm{m}$/sce의 주사속도에서 포토레지스트를 패턴하기 위한 임계에너지(threshold energy fluence) 값은 25J/cm2이며, 약 40J/cm2의 에너지 밀도에서 하부기판의 손상이 발생하기 시작하였다. 글미 1은 Nd:YAG 레이저 4고조파를 이용하여 포토레지스트를 식각한 경우 SEM 표면사진(위)과 단차특정기에 의한 단면형상(아래)이다. ITO 막의 레이저에 의한 직접 패턴 결과, ITO 막은 레이저 펄스에 의한 급속 가열 및 증발에 의한 메커니즘으로 식각이 이루어지며, 레이저 파장에 따른 광흡수 정도의 차이에 의해 2고조파 (532nm)에서 ITO 막의 가공 품질이 4고조파(266nm)에 비해 우수하며 패턴의 폭도 출력에 따라 제어가 용이하였다. 그림 2는 Nd:YAG 레이저 2고조파를 이용하여 ITO를 식각한 경우 SEM표면 사진(위)과 단차측정기에 의한 단면형상(아래)이다. 격벽 재료의 레이저에 의한 직접 패턴 결과, Ar+ 레이저(514nm)는 출력 밀도 32NW/cm2에서 격벽을 유리 기판의 경계면까지 식각하였다. Nd:YAG 레이저(532nm)는 laser fluence가 6.5mJ/cm2에서 격벽을 식각하기 시작하였으며, 19.5J/cm2에서 유리기판의 rudraus(격벽 두께 130$\mu\textrm{m}$)까지 식각하였다.

• Fire Science and Engineering
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• v.18 no.3
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• pp.57-73
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• 2004

Quantitative safety analysis through a fault tree method has been conducted for a fire broken out over the spilling LNG from a pilot LNG tank, which may have 4 types of scenarios causing potentially risky results. When we consider LNG release from venting pipelines as a first event, any specific radius of Low Flammable Limit(LFL) has not been built up. The second case of LNG outflow from the rupture of storage tank which will be the severest has been analyzed and the results revealed various diffusion areas to the leaking times even with the same amount of LNG release. As a third case LNG leakage from the inlet/outlet pipelines was taken into consider. The results showed no significant differences of LFL radii between the two spilling times of 10 and 60 minutes. Hence, we have known the most affecting factor on the third scenario is an initial amount of LNG release. Finally, the extent of LFL was calculated when LNG pipelines around the dike area were damaged. In addition, consequence analysis has been also performed to acquire the heat radiation and flame magnitude for each case.

• The Journal of the Korea institute of electronic communication sciences
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• v.1 no.1
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• pp.63-69
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• 2006

The optical submarine cable has a long distance cable and the repeater for optical amplification compared to territorial optical cable so conventional OTDR utilization for the optical submarine cable is limited. in case the optical core in the optical submarine cable system cut, by using Coherent OTDR that utilize OTDR path in repeater the cable fault point can be detected and in case the faulty of the copper tube in the cable that provide power for the repeater to amplify optical signal, the ways using the current/voltage characteristic, the capacitance per Km and so on is required. this report suggest efficient fault location detecting mechanism by categorized cable fault type.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.40 no.8
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• pp.721-724
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• 2016

Because of the inherent uncertainties caused by the manufacturing process variations, future loading conditions, and incomplete damage models, the lifetimes of mechanical structures under field conditions are significantly different from the results obtained in the laboratories. In this study, a dual sensor was developed to prognosticate the fatigue failure of structures under these uncertain conditions, and its effectiveness was demonstrated on a rectangular columnar structure under repeated uni-axial loading. The dual sensor is a slightly weaker structure embedded in the target structure, so that failure occurs in the sensor earlier than in the target structure. From the signal differences in the strain gauges in the embedded dual sensor, it is possible to differentiate between the normal status and warning status, even under variable loads.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.21 no.10
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• pp.1973-1980
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• 2017

In the case of a small UUV operating an active synthetic aperture sonar, various velocity disturbances may occur on the path due to the influence of external underwater environment, and this causes phase errors in coherent synthetic aperture processing, which has a large influence on the detected image. In this paper, when a periodic sinusoidal velocity disturbance is generated in the traveling direction, the phase generated by the round trip slope range at each position is estimated the cross correlation coefficient for multiple received signals and compensated the position variation in the overlapped DPC by the average value within the maximum allowable width. Through simulations, it has been confirmed that the images degraded by the velocity disturbance amplitude and fluctuating frequency of the UUV are removed from the false targets and the performance of azimuth resolution is improved by the proposed phase compensation method.

• Applied Microscopy
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• v.33 no.4
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• pp.291-298
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• 2003

Exposure to stressful stimuli is known to activate the peripheral sympathetic nervous system and the adrenal gland. In this study, we evaluated the effects of high-salt diet on the mouse adrenal medulla using the tyrosine hydroxylase (TH) immunohistochemistry and the transmission electron microscopic observation. Immunoreactivity for TH was increased after high-salt diet. Especially, the TH immunoreactivity was stronger in 4 days high-salt diet mouse than that of 4 weeks. TH immunoreactivity was mainly present in the cytoplasm and granules of the noradrenaline cells. After high-salt diet, the noradrenaline cells exhibited the ultrastructural alterations consisting of areas of empty cytoplasm, expanded granules, and some damaged mitochondria. These results suggest that high-salt diet may be a factor of stressful stimuli on the mouse.