• 한국해안·해양공학회논문집
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• 제36권1호
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• pp.1-10
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• 2024

해상 산업시설을 중심의 부유식 구조물 수요가 생활 밀접형 시설로 점차 확대됨에 따라, 부유 구조물의 동요를 저감하기 위한 기술 필요성이 대두되고 있다. 본 연구는 부유체 외부에 유공벽이 설치된 부유식 구조물을 제시하고, 규칙파 및 불규칙파 조건에서의 주파수 영역 해석을 통해 해당 구조물의 응답을 조사하였다. 제안된 구조물은 내부 부유체와 유공벽이 포함된 외부 부유체가 결합된 형태로, 유공률별(0~30%) 해석 모델을 생성해 부유체 중심점과 가장자리에서의 상하 및 회전 동요가 비교되었다. 해석 결과는 유공벽의 유공률 증가를 통해 부유체의 상하 및 회전 동요를 저감할 수 있음을 보여주었다. 또한 제안된 부유체를 사용함으로써 무유공 부유체 대비 규칙파와 불규칙파 조건에서 각각 10%, 2% 내외의 응답 감소 효과가 나타남을 확인할 수 있었다.

• 보건교육건강증진학회지
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• 제9권2호
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• pp.12-40
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• 1992

The study is designed to grasp school adminstrators' attitudes toward school health education and practices of school health education and to analyse relationships between characteristics of school administators and their attitudes to school health education and between their attitudes and practices of school health education in elementary and secondary schools, so that it may offer the basic materials for improving the school health education. This study was obtained from 740 school administrators all over the country, who have attended Certification Training of Elementary and Secondary Principal opened at Korea National University of Education from July, 1, 1991 to August 9, 1991. The results are summarized as follows: 1. School administrators' attitudes toward school health education 1) As for view of health education, those who believed that health is the means of education was 36.2%. 2) In methods of school health, those who want regular health education was 75% ; irregular health education 25%. 3) As for attitudes of those chose irregular health education as teaching methods : (1) In teaching hours, the morning and afternoon class meetings was highest 50.8% of whole. (2) In teaching staffs, home room teacher was 51.9% ; school nurse 34.8%. (3) In frequency of irregular health education, 1-2 times a week was 38%, 1-2 times a month 32.6%, 1-2 times a semester 11.8%. (4) As for teaching methods of irregular health education, practice through the health function showed higher frequency than other methods 4) As for attitudes of those chose regular health education as teaching methods : (1) Most of respondents had opinion that regular health education should be carried out by the subject of physical education in both elemetary and secondary schools. (2) Opinion that school nurse should be in charge of regular health education was a little higher than other ones. (3) More than a half of the whole thought that 1-2 hours a month was suitable for carrying out regular health education. (4) Therr-fourth of those who wanted regular health education chose the using of audiovisual material as a teching method. (5) Curriculum recommended first by respondents for the school health education were personal habits and health, prevention and control of disease, mental and emotional health etc. (6) As for impedimental factors in the development of school health education, it was shown as following order : the lack of professional health education instructors, the lack of budget and administrative support, the lack of instructional materials and instruments etc.

• 한국해양공학회:학술대회논문집
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• 한국해양공학회 2001년도 추계학술대회 논문집
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• pp.164-168
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• 2001

The motion of a ship advancing in regular waves is analyzed in the time-domain using the convolution integral of the radiation forces. The memory effect functions and infinite frequency added masses are obtained from the solution of the three dimensional improved Green integral equation in the frequency domain by making use of the Fourier transformation. The ship motions in regular waves have been calculated by both the time and frequency domain methods. It has been shown that they agree very well with each other. The present time-domain method can be used to predict the time histories of unsteady motions in irregular waves. It can also be used to calculate the hydrostatic and Froude-Krylov forces over the instantaneous wetted surface of the ship hull to predict large ship motions, in a practical sense, advancing in large amplitude waves.

• Nutrition Research and Practice
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• 제1권4호
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• pp.349-355
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• 2007

Stress has been known to change dietary behaviors and food intakes in individuals. The purpose of this study was to investigate the effect of stress level on the frequency and the amount of snack consumption. The high stress group (HS) showed significantly higher frequency of consumption for bread, chips, cookies, ramyeon, and frozen snacks (p<0.05) compared to low stress group (LS) with higher frequency of snack consumption (p<0.01), and increased intakes of energy, carbohydrates, and sodium from snacks (p<0.01) than LS. As the stress level became higher, the proportions of students with irregular meals, overeating, and night snacking increased (p<0.01). Also, 33.0% of the subjects answered that they consumed an increased amount of snacks when they were feeling stressed. Our results indicated that stress has negative influence on snack consumption in middle school girls.

• 한국소음진동공학회논문집
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• 제16권5호
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• pp.521-528
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• 2006

The vibration fatigue is suitable case of fatigue problem that system is exposed to the random or other irregular sources. Even some kinds of effort using power spectral density (PSD) and statistical concept was presented to cope with the intangible force signal, it is still lack of providing a reasonable solution when its exciting frequency is near or beyond of first eigenvalue. In this paper, energy approach method is presented to calculate a vibration induced fatigue damage in frequency domain. Since the corresponding damage become much larger than nominal case when the vibration is coupled with a mode shape of given structure, the new technique compensate the characteristics of structure with a measured frequency response function (FRF) between forcing acceleration and responding stress.

• 한국해양공학회지
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• 제12권2호통권28호
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• pp.33-42
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• 1998

In the presence of incident waves with different frequencies, the second order sum and difference frequency waves due to the nonlinearity of the incident waves come into existence. Although the magnitudes of the forces produced on a Tension Leg Platform(TLP) by these nonlinear waves are small, they act on the TLP at sum and difference frequencies away from those of the incident waves. So, the second order sum and difference frequency wave loads produced close to the natural frequencies of TLPs often give greater contributions to high and low frequency resonant responses. The second order wave exciting forces and moments have been obtained by the method based on direct integration of pressure acting on the submerged surface of a TLP. The components of the second order forces which depend on first order quantities have been evaluated using the three dimensional source distribution method. The numerical results of time domain analysis for the nonlinear wave exciting forces in regular waves are compared with the numerical ones of frequency domain analysis. The results of comparison confirmed the validity of the proposed approach.

• 한국해양공학회지
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• 제19권6호통권67호
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• pp.58-63
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• 2005

The estimation of springing responses for recent ships is carried out, and application to a ship design is described. To this aim, springing effects on hull girder were re-evaluated, including non-linear wave excitations and torsional vibrations of the hull. The Timoshenko beam model was used to calculate stress distribution on the hull girder, using the superposition method. The quadratic strip method was employed to calculate the hydrodynamic forces and moments on the hull. In order to remove the irregular frequencies, we adopted 'rigid lid' on the hull free surface level, and addedasymptotic interpolation along the high frequency range. Several applications were carried out on the following existing ships: The Bishop and Price's container ship, S-175 container ship, large container, VLCC, and ore carrier. One of them is compared with the ship measurement result, while another with that of the model test. The comparison between the analytical solution and the numerical solution for a homogeneous beam-type artificial ship shows good agreement. It is found that Most springing energy comesfrom high frequency waves for the ships having low natural frequency and North Atlantic route etc. Therefore, the high frequency tail of the wave spectrum should be increased by $\omega$$\^{-3}$ instead of $\omega$$\^{-4}$ or $\omega$$\^{-5}$ for the springing calculation.

• 한국해양공학회:학술대회논문집
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• 한국해양공학회 2004년도 학술대회지
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• pp.173-178
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• 2004

The estimation of springing responses for recent ships are carried out and application to a ship design are described. To this aim, springing effects on hull girder were re-evaluated including non-linear wave excitations and torsional vibrations of the hull. The Timoshenko beam model was used to calculate stress distribution on the hull girder by the superposition method. The strip method was employed to calculate the hydrodynamic forces and moments on the hull. In order to remove the irregular frequencies, we adopted 'rigid lid' on the hull free surface level and added asymptotic interpolation along the high frequency range. Several applications to the existing ships were carried out. They are Bishop and Price's container ship, S-175 container ship, large container, VLCC and ore carrier. One of them is compared with ship measurement result while another with that of model test. Comparison between analytical solution and numerical one for homogeneous beam type artificial ship shows good agreement. It is found that most springing energy came from high frequency waves for the ships having low natural frequency and North Atlantic route etc. Therefore, the high frequency tail of the wave spectrum should be increased by $\omega^{-3}\;instead\;of\;\omega^{-4}\;or\;\omega^{-5}$ for springing calculation.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2000년도 제13회 신호처리 합동 학술대회 논문집
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• pp.59-62
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• 2000

본 논문에서는 실측 데이터를 기준으로 9가지의 다양한 모델을 제안한 JTC(Joint Technical Committee) 모델을 전송 채널 모델로 채택하여 채널의 PDP(Power Delay Profile)의 불규칙성 따른 OFDM (Orthogonal Frequency Division Multiplexing) 통신 시스템의 성능을 분석하였다 전송 채널의 불규칙성은 Main profile의 길이, Peak 위치, Echo profile의 지연 시간, 그리고 Echo profile의 강도로 분류하여 각각에 따른 PDP를 설정하여 각 모델에 따른 OFDM 시스템의 성능 분석을 하였다.

• 한국산림과학회지
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• 제82권1호
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• pp.7-11
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• 1993

상해(傷害)에 기인하여 양버즘나무(Platanus occidentalis L.) 수간에 형성된 팽창조직(膨脹組織)의 해부학적(解剖學的) 특성(特性)을 조직학적(組織學的) 및 수량적(數量的) 측면(側面)네서 정상조직(正常組織)과 비교(比較) 고찰(考察)하였다. 팽창조직은 정상조직에 비하여 세포배열이 불규칙적이고 도관요소내 타일로시스가 현저하게 발달되어 있으며, 후벽화(厚壁化)된 목섬유가 흔히 관찰된다는 점, 복합관공이 덜 나타난다는 점에서 차이를 나타내었고, 관공의 직경이 작고 도관요소와 목섬유의 길이가 짧으며 도관빈도(vessel frequency)는 작은 반면, 도관요소내 계단상 천공관의 bar 수(數)가 많으며, 방사조직 빈도(ray frequency)가 크고 방사조직의 폭이 넓으나 높이가 작은 특성(特性)을 나타내었다.