• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2013년도 추계학술대회 논문집
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• pp.320-324
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• 2013

A crack identification method using an equivalent bending stiffness for cracked beam and committee of neural networks is presented. The equivalent bending stiffness is constructed based on an energy method for a straight thin-walled pipe, which has a through-the-thickness crack, subjected to bending. Several numerical analysis for a steel cantilever pipe using the equivalent bending stiffness are carried out to extract the natural frequencies and mode shapes of the cracked beam. The extracted modal properties are used in constructing a training patterns of a neural network. The input to the neural network consists of the modal properties and the output is composed of the crack location and size. Multiple neural networks are constructed and each individual network is trained independently with different initial synaptic weights. Then, the estimated crack locations and sizes from different neural networks are averaged. Experimental crack detection is carried out for 3 damage cases using the proposed method, and the identified crack locations and sizes agree reasonably well with the exact values.

• Structural Engineering and Mechanics
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• 제87권4호
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• pp.391-403
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• 2023

In this study, a new type of self-centering beam-column joint with tapered steel plate links is proposed. Firstly, mechanical property of the basic joint (with the prestressed steel strands only, to provide the self-centering ability) and the combined joint (with both the prestressed steel strands and tapered steel plate links, to provide self-centering and energy dissipation simultaneously) is theoretically analyzed. Then, three joints with different dimensions and combinations of tapered plate links are designed and tested through a series of quasi-static cyclic loading tests. Test results show that a nearly bilinear elastic moment-rotation relationship for the basic joint is obtained. With the addition of tapered steel plate links, typical flag-shape hysteretic curves are obtained, which indicates good self-centering and energy dissipating ability of the combined joint. By installing multiple tapered plate links, stiffness and bearing capacity of the beam-column joint can be enhanced. The theoretical moment-rotation relationships agree well with the test results. A simplified macro model of the proposed joint is developed using OpenSees, which simulates reasonably well its hysteretic behavior.

• 한국환경생태학회지
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• 제29권4호
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• pp.636-644
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• 2015

본 연구는 2014년 현재 입산시간지정제를 시행하고 있는 7개 국립공원 탐방객에 대한 설문조사를 실시하여, 입산시간지정제의 정착에 미치는 요인을 파악하였다. 설문 응답자들의 입산시간지정제에 대한 인지율이 60.7%로, 제도에 대한 홍보는 성공적인 것으로 나타났다. 응답자들이 인식하는 재난 안전사고 원인에 대한 중요도에 대한 요인분석 결과, '탐방객의 부주의', '공원 안전관리 부족', '탐방객 산행 준비 부족'으로 축약할 수 있었다. 요인분석을 통해 추출된 3개 잠재 요인과 응답자의 사회경제적 특성을 독립변수로 하고 입산시간지정제 취지에 동의하는 정도를 종속변수로 한 회귀분석 결과, 재난 안전사고의 원인이 탐방객 산행 중 부주의와 탐방객 산행 준비 부족이라고 생각하는 사람일수록 입산시간지정제 취지에 동의하는 것으로 나타났다. 이는 입산시간지정제 취지에 동의하지 않는 사람일수록 안전사고에 개인의 책임이 없다고 생각한다는 의미로, 재난 안전사고 예방을 위해서는 공원 내 안전시설 설치보다는 탐방객들에게 안전사고에 대한 경각심을 주는 홍보에 투자하는 것이 더 효과적임을 시사한다.

• 대한소아치과학회지
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• 제37권4호
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• pp.545-550
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• 2010

Freeman-Sheldon Syndrome(FSS)은 드물게 발생하는 선천성 유전 질환으로 휘파람을 부는 듯한 특징적인 안모로 인해 'Whistling face syndrome'으로 불리워진다. 또한 편평한 안모, 긴 인중(philtrum), 낮은 비연골이 나타나 두드러진 안면이상을 보이고, 내반족(club foot, 內反足), 손가락의 관절구축(joint contracture)으로 인한 풍차 모양의 손을 가지며, 지능은 보통 정상이다. 본원에 내원한 환아는 이 질환의 특징적 양상인 구강 주위 근육의 수축으로 소구증 및 개구제한, 높은 구개 및 부정교합, 치열의 심한 총생을 보여 구강위생이 매우 불량하였고 치과치료에 비협조적이었다. 소아치과적 행동조절 및 구강위생관리, 섭식장애의 상담으로 치과적 문제는 다소 개선되었으나, 안과 및 정형외과, 신경정신과, 교정과, 마취과적 문제로 인해 다양한 협진이 필요하며 계속적인 관찰 및 치료가 요구되기에 이를 보고하는 바이다.

• Steel and Composite Structures
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• 제15권1호
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• pp.103-130
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• 2013

Fire performance and fire safety of high-rise buildings have become major concerns after the disasters of World Trade Center in the U.S. in 2001 and Windsor tower in Spain in 2005. Performance based design (PBD) approaches have been considered as a better method for fire resistance design of structures because it is capable of incorporating test results of most recent fire resistance technologies. However, there is a difficulty to evaluate fireproof performance of large structures, which have multiple structural members such as columns, slabs, and walls. The difficulty is mainly due to the limitation in the testing equipment, such as size of furnace that can be used to carry out fire tests with existing criteria like ISO 834, BS 476, and KS F 2257. In the present research, a large scale calorie meter (10 MW) was used to conduct three full scale fire tests on medical modular blocks. Average fire load of 13.99 $kg/m^2$ was used in the first test. In the second test, the weighting coefficient of 3.5 (the fire load of 50 $kg/m^2$) was used to simulate the worst fire scenario. The flashover of the medical modular block occurred at 62 minutes in the first test and 12 minutes in the second test. The heat resistance capacity of the external wall, the temperatures and deformations of the structural members satisfied the requirements of fire resistance performance of 90 minutes burning period. The total heat loads and the heat values for each test are calculated by theoretical equations. The duration of burning was predicted. The predicted results were compared with the test results, and they agree quite well.

• 한국초전도학회:학술대회논문집
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• 한국초전도학회 1999년도 High Temperature Superconductivity Vol.IX
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• pp.260-260
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• 1999

We compared c-axis tunneling characteristics of small stacked intrinsic Josephson junctions prepared on the surface of pristine, I-, and HgI$_2$-intercalated Bi$_2Sr_2CaCu_2O_{8+x}$ (Bi2212) single crystals. The R(T) curves are almost metallic in I-Bi2212 specimens, but semiconducting in HgI$_2$-Bi2212 ones.· The transition temperatures were 82.0 K, 73.0 K, and 76.8 K for pristine Bi2212, I-Bi2212, and HgI2-Bi2212 specimens, respectively, consistent with p-T$_c$ phase diagram. Current-voltage (IV) characteristics of both kinds of specimens show multiple quasiparticle branches with well developed gap features, indicating Josephson coupling is established between neighboring CuO$_2$ planes. The critical current I$_c$ of I-Bi2212 is almost the same as of that of pristine crystals, but I$_c$ is much reduced in Hgl$_2$-Bi2212. In spite of expanded interlayer distances, the interlayer coupling is not significantly affected in I-Bi2212due to holes generated by iodine atoms. The coupling in HgI$_2$-Bi2212 is, however, weakened due to inertness of HgI$_2$ molecules and the expansion of interlayer distance. Relation between the superconducting transition temperature T$_c$ and the critical current I$_c$ seems to contradict Anderson's interlayer-pair-tunneling theory but agree with a modified version of it.

• Structural Engineering and Mechanics
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• 제10권1호
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• pp.53-66
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• 2000

This paper proposes a simple numerical model for use in a finite analysis (FEA) of scaffold-shoring systems. The structural model consists of a single set of multiple-story scaffolds with constraints in the out-of-plane direction at every connection joint between stories. Although this model has only two dimensions (termed the 2-D model), it is derived from the analysis of a complete scaffold-shoring system and represents the structural behavior of a complete three-dimensional system. Experimental testing of scaffolds up to three stories in height conducted in the laboratory, along with an outdoor test of a five-story scaffold system, were used to validate the 2-D model. Both failure modes and critical loads were compared. In the comparison of failure modes, the computational results agree very well with the test results. However, in the comparison of critical loads, computational results were consistently somewhat greater than test results. The decreasing trends of critical loads with number of stories in both the test and simulation results were similar. After investigations to explain the differences between the computationally and experimentally determined critical loads, it was recommended that the 2-D model be used as the numerical model in subsequent analysis. In addition, the computational critical loads were calibrated and revised in accordance with the experimental critical loads, and the revised critical loads were then used as load-carrying capacities for scaffold-shoring systems for any number of stories. Finally, a simple procedure is suggested for determining load-carrying capacities of scaffold-shoring systems of heights other than those considered in this study.

• 한국통신학회논문지
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• 제39C권4호
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• pp.400-406
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• 2014

본 논문에서는 주어진 영역 안에서 다중 청소로봇을 동시에 운용하여 전력 소비량을 최소화하는 방법을 제안한다. 협력 게임 이론 중 Nash 협상 해법을 이용하여 다중 청소로봇 사이의 가용 자원 및 대상 영역의 특성을 고려하여 대상 영역을 공평하고 효율적으로 관리하여 자원 효용을 극대화하였으며 궁극적으로 이를 통하여 총 소비전력량을 최소화 할 수 있다. 본 논문에서는 가용 자원 및 대상 영역의 특성을 포괄할 수 있는 효용 함수를 정의하고 이를 통한 다중 로봇 간 협상 게임을 통하여 공평하고 효용이 파레토 최적인 지점에서 각 청소로봇의 해당 영역이 결정된다. 시뮬레이션을 통하여 제안한 해결 방법이 임의 공간 할당 방법 대비 소비전력량 면에서 15-30% 이상의 효율이 개선되는 것을 확인할 수 있었다.

• 전자공학회논문지
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• 제50권3호
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• pp.16-22
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• 2013

n 개의 균일한 결합선로를 해석하기 위하여 2n-port 어드미턴스 매트릭스의 추출에 기초한 일반적인 특성화 절차가 제시된다. 본 논문에서는 비대칭 다중 결합선로를 해석하기 위하여 시간영역의 유한차분법을 사용하여 정규화 모드 파라미터 접근법의 적용을 제안한다. 주파수 의존적인 정규화 모드 파라미터는 2n-port 어드미턴스 매트릭스로부터 얻어지고, 이로부터 주파수 의존적인 전파상수와 유효 유전율 및 결합선로의 특성임피던스를 계산할 수 있다. 이 기법을 설명하기 위해 몇몇의 실질적인 다중 유전체상의 결합선로 구조들이 모의 실험되었으며, 특히 전도체가 유전체 사이에 내재된 형태의 선로가 해석되었다. 시간영역 유한 차분법을 활용한 결과는 Spectral Domain Method의 모의실험 결과와 비교하였고, 잘 일치함을 보였다. 시간영역의 특성화 절차에 기인한 유한차분법은 얇거나 두꺼운 혼성 구조 뿐 아니라 다층 PCB상의 다중의 전도체 결합 선로 설계를 위한 훌륭한 광대역 모의실험 도구가 됨을 볼 수 있다.

• 대한치과기공학회지
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• 제28권1호
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• pp.67-81
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• 2006

This research has been attempt to examine closely factors that high cost and value to overall satisfaction state for dental implant prosthesis, re-utilization intention, inducement intention of the general hospital dental service user and provide basis data necessary to establish competitive general hospital dentistry management strategy. Collected data using own recording way questionnaire from April 17, 2004 to May 15, 2004 choosing 142 people that agree on this research and question of 361 people that dental implant prosthetic treatment finished from March 1, 1999 to March 1, 2004 for this. Major analyzation consequences are as follows : First, general satisfaction, re-utilization intention, inducement intention for implant prosthesis that highly correlation variables are kindness, explanation, medical treatment level and appreciation of the aesthetic. Second, correlation is high relatively between re-utilization intention, inducement intention in the 3 variables such as general satisfaction re-utilization intention, inducement intention. Third, the result of multiple regression analysis showed that most significant effective factors are satisfaction with explanation of dental implant prosthesis between the 3 dependant variables such as general satisfaction, re-utilization intention, inducement intention. In looking into these consequence, how to improve that raise satisfaction about dental implant prosthetic treatment and to establish patient focused care service system for dental implant prosthesis, it is consider that explain enough about implant prosthesis and raise quality of medical examination and treatment level, including satisfied with fabrication of good esthetic dental implant prosthesis.