• 대한조선학회지
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• 제24권2호
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• pp.36-46
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• 1987

This paper presents the results of seakeeping tests in a container ship model in irregular head waves. A time domain signal generating procedure is devised so that the wave maker behaves in accordance with the specified wave spectrum. The surface elevation of generated waves is measured and analysed to render the recorded wave spectrum for comparison with the specified one. Correction is made to the time domain signal until the differences between the two spectra become negligible. The motion responses and vertical acceleration of the self-propelled ship model are measured and analysed by both the spectral and the double amplitude methods. The two methods give nearly same statistical values. Finally the recorded spectra are compared with those calculated from the frequency domain motion analysis to show the credibility of the experimental results.

• 동의생리병리학회지
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• 제34권1호
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• pp.53-59
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• 2020

Dietary habits are known to be closely related not only to chronic diseases such as cardiovascular disease and diabetes, but also to self-rated health (SRH). Consequently, there is a highly important lifestyle component in maintaining a healthy life. The aim of the present study was to determine the correlation between diverse dietary habits based on the Sasang constitutions (SC) and SRH. The data were collected from 2,984 participants who met the constitution pharmacology criteria and whose SC were clinically confirmed by SC professionals. Dietary habits were observed by assessing the regularity of diet, meal volume, and meal speed; single-answer questions were used for SRH. Fisher's exact/chi-square test and logistic regression were used to analyze the correlation between dietary habits depending on constitutional type and SRH. In association with constitutional SRH, the Taeum type is related to the amount of meal, the Soeum and Soyang types are related to the regularity of meal and meal volume. In the Taeum type, there was a significantly higher risk of lower SRH when meal volumes were irregular less than previous amounts. Irregular diet, as well as increased or decreased meal volume, negatively correlated with SRH in the Soeum type; in the Soyang type, irregular diet and decreased or irregular meal volume negatively affected SRH. This showed the presence of the different effects of dietary habits on health depending on constitution and also confirmed the association of the regularity of diet and meal volume based on constitution and the frequency of bad dietary habits with SRH. We suggest that personalized healthcare with adequate dietary improvement considering constitution is needed for health management or improvement.

• 한국해안·해양공학회논문집
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• 제30권4호
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• pp.153-165
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• 2018

본 연구는 olaFlow을 이용하여 먼저 소스에 의한 불규칙파의 조파에서 목표주파수스펙트럼과 조파된 파랑의 주파수스펙트럼과의 비교 검토로부터 olaFlow의 타당성을 검증하였다. 이로부터 불규칙파랑 하 3차원투과성잠제를 대상으로 잠제 주변에서 형성되는 파고분포와 같은 수면변동의 특성과 설상사주의 주요외력으로 작용하는 평균유속, 연안류 및 난류운동에너지 등을 포함한 유속장의 특성을 수치적으로 검토하였다. 수치해석결과에 따르면 잠제 사이의 개구폭이 감소할수록 개구부 중앙에서는 자승평균평방근파고가 증가하지만 개구부 배후에서는 자승평균 평방근파고가 감소하며, 잠제의 개구폭이 넓을수록 강한 연안류가 형성됨과 동시에 수송유량이 증가되는 것을 확인할 수 있었다. 이로부터 잠제 배후에 형성되는 설상사주의 형성원인을 파악할 수 있었다.

• 한국해양공학회지
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• 제31권2호
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• pp.81-90
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• 2017

The 1MW OTEC (Ocean Thermal Energy Conversion) platform was designed for application in equatorial seas. In this study, the OTEC platform was investigated using numerical and experimental methods. An octagon-shaped OTEC platform was investigated using the Ocean Engineering Basin of KRISO. These experiments included various tests of regular waves, irregular waves and irregular waves with current (wave+current). The responses of the platform in regular waves showed good agreement between the numerical and experimental results, including the motion RAO, wave run up, and mean drift force. The peak period of heave and pitch motions were observed around 0.5 rad/s, and the effect of the total reflection was found under short wave conditions. The standard deviation (STD) of the platform motion was checked in irregular waves of equatorial and Hawaiian seas. The STD of the pitch was less than $4^{\circ}$ different from the operability requirement under equatorial conditions and the surge STD of the wave frequency showed good agreement between the numerical and experimental results. The STD values of the surge and pitch were increased 66.6% and 92.8% by the current effects in irregular waves, but the pitch STD was less than $4^{\circ}$ under equatorial conditions. This study showed that the STD of the surge was affected by spring effects. Thus, the watch circle of the platform and tension of the mooring lines must be evaluated for a specific design in the future.

• 대한조선학회논문집
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• 제38권3호
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• pp.47-53
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• 2001

선박이 파랑중에 충격력을 받거나 불규칙한 외력을 받았을 경우에 시간영역에서의 운동방정식을 해석하는 것이 편리하다. 본 연구에서는 주파수영역에서 3차원 Green함수를 이용한 패널방법을 사용하여 부가질량, 파랑감쇠계수, 1차항 파강제력과 시간평균된 표류력을 계산하였고, 기억효과를 포함한 시간영역의 운동방정식에서 Newmark-$\beta$방법을 사용하여 수치적분하였다. 계산 예로 계열 60 선박($C_B=0.7$)을 선정하여 불규파중에서 전진할 때의 6자유도 운동, 선수미에서의 가속도, 갑판침수 횟수 및 선저 노출 횟수 등을 계산하였다. 또한 2차항 파강제력을 운동방정식에서 고려하여 파도중에서 추력증가에 대해서 검토하였다.

• 대한영양사협회학술지
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• 제27권1호
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• pp.1-14
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• 2021

This study aimed to investigate the relationship between meal regularity (i.e. breakfast intake and meal-times), and the risk of metabolic syndrome (MetS) among generally healthy Korean single-person household adults (≤60 years, n=594) based on the Seventh Korean National Health Examination and Nutrition Survey (KNHANES) (2016~2018). Among men (n=325), the breakfast intake frequency was not significantly associated with the pervalence of MetS. However, men consuming a regular meal at least once a day showed a lower prevalence of MetS compared to those whose meals were irregular. These patterns remained after adjusting for age, smoking and drinking habits, individual income, education level, exercise, and total calorie intake. An association between meal regularity and MetS risk was observed in post-menopausal women (n=84), but not in pre-menopausal women (n=185). More specifically post-menopausal women with irregular breakfast eating habits or eating no breakfast at all showed a significantly higher risk of MetS than those eating breakfast regularly after the adjustment. The analysis revealed an odds ratio (OR) of 8.46, confidence intervals (CIs): 1.149~62.199, P<0.05 in irregular breakfast eaters, and an OR of 13.377, CIs: 1.665~107.511, P<0.05, in those who ate no breakfast. Furthermore, post-menopausal women who had irregular meals daily showed a higher risk of MetS than those consuming one or more regular meals/day after the adjustment (OR: 16.888, CIs: 1.258~226.655, P<0.05). In conclusion, the results from this study may be used for formulating optimal dietary guidelines for the prevention and the management of MetS in adults in single-person households.

• Journal of Ship and Ocean Technology
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• 제11권3호
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• pp.1-13
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• 2007

A semi-submersible drilling rig is regarded as one of the typical offshore structures operated in the field with moderate environments such as the Gulf of Mexico, Brazil, and West Africa. Its typical roll and pitch natural periods are around 30 seconds, which avoids prevailing regions of the wave energy spectrum, and their responses in waves are quite acceptable for common operation conditions. But large roll and pitch motions can be induced by wave difference frequency energy spectrum if the metacentric heights of a semi-submersible decrease to small values in some loading conditions, and it is because the roll and pitch natural periods increase and approach to the region where the spectral density of the low frequency wave drift moment has significant value. This paper describes the low frequency roll motion of a semi-submersible that are excited by the wave 2nd order difference frequency energy by a series of model experiments. From the model tests with several different initial metacentric heights (GM), it was observed that a semi-submersible can experience large roll motion due to the wave group spectrum.

• 대한지역사회영양학회지
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• 제6권2호
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• pp.172-181
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• 2001

The purpose of this study is to analyze the foods which 424(male 171, female 253) university students surveyed consumed frequently and to evaluate and the factors affecting their food consumption patterns. The survey was conducted at the beginning of nutrition courses each semester, March and September, 1998, with the questionnaire composed of general information, food, drinking and smoking habits, nutrition knowledge/attitude and food frequency questionnaire. The rates of alcohol drinking in male and female students were 89.2% and 78.1% respectively, and the rates of smoking were 68.1% and 1.6% in males and female. The nutrition knowledge score was higher in females than in males, but the nutrition attitude score was not significantly different between the male and female groups. The foods frequently consumed among students were cooked rice(14.3/week), kimchi(11.1/week), coffee(5.7/week), vegetables in soup, jjigae and jorim(3.5/week), carbonated beverages(3.3/week), cooked mixed rice(3.2/week). Ramyun and chocolate·candies·biscuits were frequently consumed, too. There were several factors influencing food consumption patterns. These were gender, regularity of mealtimes, the status of alcohol drinking and smoking, residence type and the levels of nutrition knowledge and attitude. Males ate more frequently cooked rice, coffee, carbonated beverages, ramyun, functional beverages and ham·sausage, while females ate more frequently cooked mixed rice and fruits. Those who had the habits of irregular mealtimes seemed to eat more soft drinks, instant foods and snacks. These trends were also found in the alcohol drinking and smoking groups. High level groups for nutrition knowledge of attitude score chose raw yellow green and green vegetables, cooked mixed rice, soybeans and seaweeds more frequently than the other groups. On the other hand, low level groups for nutrition knowledge or attitude score were apt to eat carbonated beverages and ramyun more frequently. Therefore, more attention should be taken to males, having habits of irregular mealtimes, alcohol drinking and smoking, and low level groups for nutrition knowledge or attitude score so as to improve their health.

• 대한기계학회논문집
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• 제9권6호
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• pp.706-713
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• 1985

본 논문에서는 연삭공정에서 채터의 진폭이 충분히 증가하면 숫돌차와 공작물 의 접촉이 더이상 유지되지 못하고 서로 떨어지게 되는 소위 접촉 이탈 현상에 의한 비선형 채터에 관한 연구를 수행하였다.비선형 요소인 비대칭 게인 (asymmetrical gain)을 사용하여 비선형 채터루우프를 유도 하였으며 기술 함수 방법(describing function method)에 의해 복소수 평면에서의 해석을 수행 하였다.또한 수치 시뮬레 이션에 의한 시간 영역에서의 해석을 수행 하였으며 그 결과를 서로 비교하였다. 이 와같은 연구를 통하여 그 비선형 효과에 의해 발생되는 연삭 채터의 특징적 현상을 구 명하였다.

• 동아시아식생활학회지
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• 제24권5호
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• pp.552-563
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• 2014

This study was performed to investigate the dietary habits and nutritional knowledge of elementary school students (boy : 250, girl : 250) by gender. Frequency of skipping breakfast was high in both boys and girls. Duration of mealtime was significantly higher for boys compared with girls (p<0.001). Regularity of meals was not significantly different between boys and girls. Reason for irregular meals was 'no appetite' for both boys (39.6%) and girls (40.0%). Unbalanced diet was high in both boys (60.8%) and girls (59.6%), and problems related to dietary habits were in order of 'unbalance diet', 'irregular mealtime', 'overeating', 'skip a meal frequently', and 'eat out frequently'. Frequency of snack intake was significantly higher for girls compared to boys(p<0.05). The criterion for selecting snacks was higher for 'nutrition' compared to 'good taste' for both boys and girls. Frequency of eating out was statistically insignificant, and eating out preferences were in the order of 'Korean food', 'western food', and 'Chinese food'. Eating behavior 'eat meat, fish, egg, tofu every meal' was significantly higher for boys compared to girls (p<0.01). 'Healthful' response rates were 57.6% for boys and 58.8% for girls. Practice level of nutritional knowledge was significantly higher in girls compared to boys (p<0.001). To establish good eating behaviors, we should develop systematic and continuous education programs.