• Journal of Korean Society of Coastal and Ocean Engineers
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• v.18 no.1
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• pp.63-68
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• 2006

Time series of waterline changes during a flood/ebb cycle can be utilized for supplementary data for measuring bottom topography. The waterlines extracted from consecutive images are substituted for depth contours using water level data. The distances between contours are quantified through a rectification image process. This technique is applied to the Keunpoolan beach in the Daeijak Island near Incheon. A camera monitoring technique supported by natural water level changes produces bottom topography with high precision. It is also less time consuming and more economical. The technique also can be utilized effectively to the physical modeling f3r measuring bottom changes in the three dimensional basin.

• The korean journal of orthodontics
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• v.30 no.5 s.82
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• pp.657-668
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• 2000

The purpose of this study was to evaluate the amount and interrelationship of the soft tissue of nose and maxillary changes and to identify the nasal morphologic features that indicate susceptibility to nasal deflection in such a manner that they would be useful in presurgical prediction of nasal changes after maxillary advancement surgery in skeletal Class III malocclusion. The sample consisted of 25 adult patients (13 males and 12 females) who had severe anteroposterior skeletal discrepancy. The patients had received presurgical orthodontic treatment. They underwent a Le Fort I advancement osteotomy, rigid internal fixation, alar cinch suture and V-Y advancement lip closure. The presurgical and postsurgical lateral cephalograms and lateral and frontal facial photographs were evaluated. The computerized statistical analysis was carried out. Soft tissue of nose change to h point change ratios were calculated by regression equations. The results were as follows 1. The correlation of maxillary hard tissue horizontal changes and nasal soft tissue vortical changes were high and the ${\beta}_0$ for soft tissue to ADV were 0.228 at ANt, 0.257 at SNt. 2. The correlation of maxillary hard tissue and nasal soft tissue horizontal changes were high and the ${\beta}_0$ for soft tissue to ADV were 0.484 at ANt, 0.431 at SNt, 0.806 at Sn. 3. The correlation of maxillary hard tissue horizontal changes and width changes of ala of nose were high and the ${\beta}_0$ lot alar base width ratio to ADV were 0.002. 4. The DRI, Prominence of nose, Pre-Op CA is not a quantitative measure that can be used clinically to improve the predictability of vertical and horizontal nasal tip deflection. In this study, increases in nasal tip projection and anterosuperior rotation occur when there is an anterior vector of maxillary movement. These nasal changes were Quantitatively correlated to magnitude of maxillary(A point) movement.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2002.09a
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• pp.43-50
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• 2002

부지고유의 강지진동모사를 위해 한반도 남부의 지각감쇠(Q)에 대한 두 가지 특성을 비선형 역산을 통해 규명하였다. 한 특성은 한반도 남부의 주요 지체구조구 및 특정 주향각에 대한 Q의 이방성이고 다른 특성은 Q의 수평방향으로의 공간적 변화 특성이다. 0의 이방성은 주향에 평행한 Q와 이에 수직한 Q의 비로 정의되었다. 사용된 지진자료는 190개 지진에 대한 3,400개 기록의 푸리에스펙트럼으로서 기록의 파선 분포는 한반도 남부 대부분을 조밀하게 덮었다. 역산 방법은 Levenberg-Marquardt 비선형역산 방법을 보다 안정화시킨 수정된 Levenberg-Marquardt 방법이 사용되었으며 기존에 도출된 광역적인 지진동파라미터를 초기해로 활용하였다. 역산 결과 국내의 중요 지체구조구 중 소백산육괴와 경상분지는 서로 다른 방향의 강한 Q 이방성을 나타내었으며 Q의 공간적 분포는 지진발생위치와 매우 밀접한 상관관계를 보여주었다

• Bulletin of the Korean Space Science Society
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• 2010.04a
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• pp.29.3-29.3
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• 2010

남극세종기지 상공 중간권계면에서의 중량파(gravity wave)를 연구하기 위해 세종기지 유성 레이더로 관측한 유성 에코를 분석하였다. 2007년 이후 유성 에코의 공간적 이동으로부터 유성 관측 고도에서의 수평 바람 정보를 지속적으로 수집해왔다. 80-100 km 고도에서의 바람 프로파일에서 지구 규모의 성분인 평균 바람(Mean wind), 대기 조석 효과(Tides)를 제거하여 국지적인 규모의 중량파에 의한 바람 변화폭(wind variance)을 결정하였다. 월 단위로 평균한 결과로부터 중량파가 계절과 고도에 대한 뚜렷한 특징을 보이고 있음을 확인하였다. 남극 지역에서의 중량파는 동서방향의 바람(zonal wind)와 저층 대기의 남극 소용돌이(vortex)와 깊은 관련이 있을 것으로 생각된다. 남극 반도에 위치한 Rothera 기지에서의 관측 결과와의 비교를 통하여, 남극 반도에서 발생하는 중량파가 중간권과 저층 대기 사이에서 어떤 역할을 하는 지를 확인할 수 있을 것으로 기대한다.

• Proceedings of the KIEE Conference
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• 2008.04a
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• pp.244-245
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• 2008

본 논문은 관성센서를 이용한 무인 항공체의 자세 제어에 관한 연구를 다루었다. 항공계의 종류는 크게 고정익기와 회선익기로 나뉘는데 본 연구에서는 회전익기의 형태를 가진 Quarter Vehicle을 사통하였다. Quarter Vehicle은 4개의 프로펠러에 의한 양력과 회전 반발력으로 비행을 한다. 이때의 양력은 수평면에 대해 수직으로 추력을 발생시키므로 다른 비행체보다 불안정하며 이를 안정하게 제어하기 위해 관성 센서를 적용하여 균형을 유지한다. 본 연구에서는 관성센서를 이용하여 UAV의 자세와 균형을 안정적으로 유지하여 안정적인 비행이 가능하도록 하였다. 또한 상호 의존적인 항법 시스템으로 환경변화에 영향을 받지 않으며, 정확한 위치정보를 제공하는 GPS를 사용하여 3개 이상의 위성으로부터 정보를 받아 좌표를 계산하고 위치, 속도 및 방향을 결정하여 자율 비행이 가능하도록 설계하였다. 본 논문에서는 Quarter Vehicle의 구조와 이론적 배경을 통한 설계, 그리고 관성센서와 GPS의 적용을 위한 방법을 제시 한다.

• The korean journal of orthodontics
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• v.39 no.5
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• pp.278-288
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• 2009

Objective: The aim of this study was to investigate the changes in the center of resistance of the maxillary teeth in relation to alveolar bone loss. Methods: A finite element model, which included the upper dentition and periodontal ligament, was designed according to the amount of bone loss (0 mm, 2 mm, 4 mm). The teeth in each group were fixed with buccal and lingual arch wires and splint wires. Retraction and intrusion forces of 200 g for 4 and 6 anterior teeth groups and 400 g for the full dentition group were applied. Results: The centers of resistance were at 13.5 mm, 14.5 mm, 15 mm apical and 12 mm, 12 mm, 12.5 mm posterior in the 4 incisor group; 13.5 mm, 14.5 mm, 15 mm apical and 14 mm, 14 mm, 14.5 mm posterior in the 6 anterior teeth group; and 11 mm, 13 mm, 14.5 mm apical and 26.5 mm, 27 mm, 25.5 mm posterior in the full dentition group respectively according to 0 mm, 2 mm, 4 mm bone loss. Conclusions: The center of resistance shifted apically and posteriorly as alveolar bone loss increased in 4 and 6 anterior teeth groups. However, in the full dentition group, the center of resistance shifted apically and anteriorly in the 4 mm bone loss model.

• The Journal of the Petrological Society of Korea
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• v.13 no.4
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• pp.179-190
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• 2004

Precambrian metamorphic rocks of Yeongyang-Uljin area, which is located in the eastern part of Sobaegsan Massif, Korea, are composed of Pyeonghae, Giseong, Wonnam Formations and Hada leuco granite gneisses. These show a zonal distribution of WNW-ESE trend, and are intruded by Mesozoic igneous rocks and are unconformably overlain by Mesozoic sedimentary rocks. This study clarifies the deformation history of Precambrian metamorphic rocks after the formation of gneissosity or schistosity on the basis of the geometric and kinematic features and the forming sequence of multi-deformed rock structures, and suggests that the geological structures of this area experienced at least four phases of deformation i.e. ductile shear deformation, one deformation before that, at least two deformations after that. (1) The first phase of deformation formed regional foliations and WNW-trending isoclinal folds with subhorizontal axes and steep axial planes dipping to the north. (2) The second phase of deformation occurred by dextral ductile shear deformation of top-to-the east movement, forming stretching lineations of E-W trend, S-C mylonitic structure foliations, and Z-shaped asymmetric folds. (3) The third phase deformation formed I-W trending open- or kink-type recumbent folds with subhorizontal axes and gently dipping axial planes. (4) The fourth phase deformation took place under compression of NNW-SSE direction, forming ENE-WSW trending symmetric open upright folds and asymmetric conjugate kink folds with subhorizontal axes, and conjugate faults thrusting to the both NNW and SSE with drag folds related to it. These four phases of deformation are closely connected with the orientation of regional foliation in the Yeongyang-Uljin area. 1st deformation produced regional foliation striking WNW and steeply dipping to the north, 2nd deformation locally change the strike of regional foliation into N-S direction, and 3rd and 4th deformations locally change dip-angle and dip-direction of regional foliation.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.3
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• pp.662-668
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• 2018

Most electric rooms are located in the underground spaces of buildings. When a fire occurs in electrical equipment, the fire expands to cable insulation material, resulting in toxic smoke and combustion products. If the smoke and combustion products quickly move vertically and horizontally, the evacuation of occupants and firefighting activities will be hindered. Therefore, it is necessary to design optimal equipment for smoke control in cases of fires in electric rooms. This study analyzes the characteristics of smoke and combustion products in fires in a cubicle-type switchboard in an electric room using PyroSim, which is based on the program Fire Dynamics Simulator (FDS). The fire modeling consists of four scenarios according to the operation mode of the mechanical ventilation equipment, the amount of air supply and exhaust, and the location of the air supply slot. The analysis shows that the mechanical ventilation equipment improves the smoke density, visibility, carbon monoxide concentration, and temperature characteristics. The visibility and temperature characteristics were improved when the air flow rate and the location of the air supply slot from fire defense regulations were applied.

• The korean journal of orthodontics
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• v.31 no.1 s.84
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• pp.15-24
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• 2001

In order to achieve a desirable tooth movement, it is of great importance to control the M/F ratio and to know the location of the center of resistance. The purpose of this study was to locate the center of resistance and the axis of rotation, and to estimate the stress distribution in the periodontal ligament with experimental model. After preparing a model of an upper canine with a simulated periodontal ligament and alveolar bone, the force and moment were applied. The tooth movement was traced using measuring device with LVDTs(Linear variable differential transformers) that can measure three dimensional tooth movement in real time. The results were as follows. 1. The location of center of resistance by transverse force was $29\%$ of root length measured from alveolar crest to apex regardless of force magnitude. The position of the center of resistance is more coronal than that of two-dimensional model($42\%$). 2. The center of resistance and the axis of rotation coincide when couple moment was applied. 3. As the magnitude of moment increases, tooth tends to extrude irrespective of the direction of the moment. 4. The relationship between location of force and axis of rotation (a x b = $49.6\;mm^2$) was obtained. A tooth movement can be predicted through this formula. 5. The centers of rotation by transverse force were plotted linearly.

• Journal of the Korean Geophysical Society
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• v.2 no.1
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• pp.45-56
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• 1999

Seismic refracrion and reflection surveys were conducted along an E-W trending track of 482 m long in Ilwall-dong, Pohang. End-on spread was employed as source-receiver configuration with 2 m for both geophone interval and offset. Seismic data were acquired using 24 channels at every shot fired every 2 m along the track. Refraction data were interpreted using equations for multi-horizontal layers. Reflection data were processed in the sequence of trace edit, gain control, CMP sorting, NMO correction, mute, common offset gathering, and filtering to produce a single fold seismic section. There are two layers in shallow subsurface of the study area. Upper layer has the P-wave velocities ranging from 267 to 566 m/s and is interpreted as a layer of unconsolidated sediments. Lower layer has P-wave velocities of 1096-3108 m/s and is interpreted as weathered rock to hard rock. Most of the lower layer classified as soft rock. Upper layer has lateral variations in both P-wave velocity and thickness. The upper layer in the eastern part of the seismic line is 3-5 m thick and has P-wave velocity of 400 m/s in average. The upper layer in the western part is 8-10 m thick and has P-wave velocity of 340 m/s in average. The eastern part is interpreted as unconsolidated beach sand, while the western part is interpreted as infilled soil to develop a construction site. Three fault systems of high angle are imaged in seismic reflection section. It is interpreted that the area between these fault systems are relatively safe. Large buildings should be located in the safe ground condition of no fault and footings should be designed to be in the basement rock of 3-10 m deep below the surface.