• Earthquakes and Structures
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• 제11권3호
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• pp.421-443
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• 2016

When conducting seismic assessment of an asymmetric building, it is essential to carry out three-dimensional analysis considering all the possible directions of seismic input. For this purpose, the author proposed a simplified procedure is to predict the largest peak seismic response of an asymmetric building subjected to horizontal bidirectional ground motion acting in an arbitrary angle of incidence in previous study. This simplified procedure has been applied to torsionally stiff (TS) asymmetric buildings with regular elevation. However, the suitability of this procedure to estimate the peak response of an asymmetric building with vertical irregularity, such as an asymmetric building with setback, has not been assessed. In this article, the pushover-based simplified procedure is applied to estimate the peak response of asymmetric buildings with bidirectional setback. Nonlinear dynamic (time-history) analysis of two six-storey asymmetric buildings with bidirectional setback and designed according to strong-column weak beam concept is carried out considering various directions of seismic input, and the results compared with those estimated by the proposed method. The largest peak displacement estimated by the simplified method agrees well with the envelope of the dynamic analysis response. The suitability assessment of the simplified procedure to analysed building models is made as well based on pushover analysis results.

• 한국해안·해양공학회논문집
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• 제32권3호
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• pp.161-169
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• 2020

테트라포드로 피복된 경사식방파제 상부구조물에 파가 경사 입사할 때의 파력 변화를 관찰하기 위한 수리모형실험을 수행하였다. 입사파향은 0, 15, 30, 45° 4가지로 변화시켰으며 상부구조물 전면 및 하부면에 파압계를 부착하여 수평 및 연직파력을 계측하였다. 실험을 통해 입사각과 구조물 전면이 이루는 각도가 증가할수록 수평 및 연직 파력이 모두 감소함을 확인하였다. 실험자료 분석 결과로부터 입사파향에 대한 수평 및 연직 파력 감소율 산정식을 각각 제시하였다.

• 터널과지하공간
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• 제30권4호
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• pp.417-431
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• 2020

이 연구에서는 라이다(LiDAR) 반사강도를 이용하여 암반 풍화도 및 변질도를 산정하는 작업의 기초연구를 진행하였다. 실내 시험을 통하여 라이다 반사강도에 직접적으로 영향을 미치는 인자와 그 영향 정도를 정량적으로 고찰하고자 하였다. 영향 인자로는 주사거리, 입사각, 표면거칠기, 표면색상, 암석물성, 광물조성, 포화도를 선정하였다. 실험에서는 FARO 라이다 장비와 12가지 종류의 시험편을 사용하였다. 실험 결과 반사강도는 표면색상, 입사각, 주사거리, 암석물성, 포화도 혹은 표면습윤상태, 표면거칠기 순으로 영향을 크게 미치는 것으로 나타났다.

• 대한원격탐사학회지
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• 제34권4호
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• pp.639-647
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• 2018

This paper presents TerraSAR-X and KOMPSAT-5 sigma nought variation according to season and antenna observation configuration in Mongolia. Two types of landcover including bare surface and cropland were examined. The seasonal variation of sigma nought in cropland was about 7 dB and particularly a significant sigma nought reduction occurred after harvest. On the contrary, the Mongolia bare surface provides a consistent sigma nought values for several years with an annual variation less than 2.5 dB of standard deviation. However, the bare soil was relatively sensitive to look-direction (or ascending or descending mode) as well as incidence angle while the cropland was almost independent of antenna look-direction and small incidence angle changes. Although the look-directional variation of bare surface sigma nought was observed in this study, the look-direction anisotropic nature of the surface was not well examined. A further study would be required to account for this feature with various SAR observation configurations.

• 한국광학회지
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• 제10권2호
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• pp.120-127
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• 1999

Head-Up Display(HUP)에 사용되는 홀로그래픽 광결합기의 회절 효율 및 결상 특성을 분석하고 제작하였다. Kogelnik의 결합파이론을 통해 반사형 체적 홀로그램에 대한 각도 및 분광 대역 특성을 수치계산하고 홀로그래픽 광학소자에서의 파장 변화에 의한 색수차의 최소화 방법을 HUD의 재생각 및 초점거리 보정에 응용하였다. 또한 자동차에 사용되는 형태로 등각형(conformal type)과 비등각형(non-conformal type)의 홀로그래픽 광결합기를 비교하고 대역 특성을 실험적으로 분석하였다. 실제적으로 등각형 보다 넓은 각도 대역폭을 보이며 광학적 배율(optical power)을 지니는 홀로그래픽 광결합기를 설계, 제작하였다.

• 한국산업정보학회논문지
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• 제4권1호
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• pp.102-109
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• 1999

본 논문에서는 접지평면위에 2개의 유전체 층을 가지는 완전도체 격자구조에서의 전자파 산란문제를 간단한 방수치해석 방법으로 잘 알려진 PMM방법을 적용하여 입사각에 따라 수치해석하였다. 산란전자계는 Floquet 모드 함수의 급수로 전개하였다. 경계조건은 미지의 계수를 구하기 위하여 적용하였고, 도체의 경계조건은 접선성분의 전계와 스트립 위의 전류와의 관계를 위해 적용하였다. 입사각이 수직일 때 비유전율이 증가함에 따라 기하광학적 반사전력의 변하는 최소점은 스트립 폭이 높은 값으로 이동한다는 것은 주목되며, 이때 수직입사시 대부분의 전력은 다른 각도의 방향으로 산란된다.

• 한국해안해양공학회지
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• 제19권4호
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• pp.375-384
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• 2007

[ $Pad{\acute{e}}$ ] 근사에 의한 포물형 근사모형들을 제시하였고 $Pad{\acute{e}}$(15, 15) 근사모형은 일정 경사의 지형에 대한 엄밀해와 비교할 때 입사각 $80^{\circ}$까지 적용 가능함을 보였다. 포물형 근사식에 대한 체계적인 유도방법을 보인 후, 본 연구에서는 15차 $Pad{\acute{e}}$ 근사모형까지 나타내었고 일정 경사지형에서의 파랑변형에 대한 수치결과들을 제시하였다.

• Maxillofacial Plastic and Reconstructive Surgery
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• 제28권1호
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• pp.49-57
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• 2006

Mandibular fractures have higher incidence rate compared to facial bone fractures because of relatively prominent form. Specially, mandibular angle fractures were known as common fracture site because of morphological anatomic structure. The mandibular third molar appears to be the most frequent impacted tooth. The mandibular third molar have influence on mandibular angle fractures according to it's eruption state. Also, the mandibular angle fracture including the third molar may influence on post operative infection whether the third molar is in impacted or extracted state when reduction of fracture site is operated. The presence or absence and degree of impaction of the mandibular third molar were assessed for each patient and were related to the occurrence of the mandibular angle fracture. The extraction or non extraction of the mandibular third molar were related to the occurrence of the post operative infection in the reduction of mandibular angle fractures. In the presence of mandibular third molar, the possibility of mandibular angle fractures were relatively common. When viewing the mandibular third molar at occlusal plane, the possibility of mandibular angle fractures were high in the class C group. The possibility of mandibular angle fractures were high in the mesial angulation and partial impaction. There was a statistically significant difference(P<0.05). In complete erupted mandibular third molar, the possibility of post operative infection occurs quite often, but there was no statistical significant difference(P>0.05). In the extracted or non extracted of mandibular third molar, the post operative infection showed no statistical significant difference(P>0.05). With the results mentioned above, mandibular third molar was significantly more susceptible to mandibular angle fracture. In the reduction of mandibular angle fracture, it was recommended that mandibular third molar should be extracted especially in case of pericoronitis, periodontitis and other infections.

• 대한기계학회논문집
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• 제15권1호
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• pp.229-240
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• 1991

본 연구에서 사용한 이론과 제시된 방법의 타당성을 검토하기 위하여 익열 간 극이 무한대인 단일 익형 주위의 유동장을, 최근에 개발된 계산방법인 Lambda방법을 사용한 Dadone의 해석결과와 비교하였고, 범용의 압축기 익형인 NACA65게열 익열 유동 에 대한 Herrig의 실험값, 그리고 미분해석에 의한 점성-비점성 상호작용 방법을 사용 한 Hansen의 계산값고, 이들 조건과 동일한 상태에서 본 연구에서 제시한 방법으로 계 산한 결과와 만족할 만한 일치를 얻었다.

• 한국전문물리치료학회지
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• 제5권3호
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• pp.72-87
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• 1998

This study examined the rates of spinal abnormal curvature and the correlation of the Body Mass Index (BMI), Low Back Pain (LBP) and spinal curvature by measuring scoliosis, kyphosis, and lordosis in university students. The study population included 67 male, 92 female university students, making a total of 159, in Wonju City. Spinal curvature was measured by an electrogoniometer in a computerized skeletal analysis system. Lateral curvature of spine of more than 10 degrees was considered as nonspostural scoliosis. The correlation of BMI, LBP and the spinal curvature was analysed by Pearson's correlation coefficient and t-test. The following results were obtained: 1. The overall incidence and rate of scoliosis in cases with a greater than 10 degree curve in males was an incidence of 8 and a rate of 11%. In females the incidence was 36 and the rate 39.2%. 2. The overall incidence and rate of kyphosis of less than 20 degrees in males was a rate of 9 and an incidence of 11.9%. In females, the rate was 5 and the incidence 5.4%. In kyphosis cases of more than 40 degrees, the male rate was 5 and the incidence 7.7%. For female the rate was 13 and the incidence 14.2%. 3. The overall incidence and rate of lordosis with curves of less than 20 degrees was a rate of 6 for males and an incidence of 9.0%. For females, the rate was 5 and the incidence 5.4%. In cases of more than 50 degrees lordosis, the female rate was 2 and the incidence 2.2%. There were no males in this category. 4. There was a negative correlation between kyphosis and BMI. The greater the kyphotic curve, the less the BMI in males (p<0.05). There was no significant BMI difference by gender in either scoliosis or lordosis. There was, however, a significantly decreased sacral angle in the female group with LBP. The results of this study cannot be generalized to the general population because the subjects were all from one university. The measurements were quite reliable because the angles determined by the Metrocom System were highly correlated with radiologic findings. This study shows the need for a regular screening system for spinal curvatures in university health examination procedures.