• 한국항해항만학회:학술대회논문집
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• 한국항해항만학회 2006년도 추계학술대회 논문집(제1권)
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• pp.205-210
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• 2006

해양구조물 설계시 급격한 파랑에 의한 충격력은 구조물 안전을 위한 중요한 설계인자이다. 이러한 충격력은 과도한 하중이 극히 짧은 시간 사이에 발생하는 현상으로 실험적 또는 수치해석적으로 해석하기 매우 어려운 문제이다. 본 연구에서는 급격한 파랑에 의한 충격력을 해석하기 위하여 수치파수조를 이용하여 N.S. 방정식에 기반한 수치해석을 수행하였다. 임의파를 선형중첩에 기반하여 조파기를 작동시켜 재현하였고 다블록격자하에서 수직실린더에 작용하는 충격력을 수치해석하였다. 한편 자유표면은 V.O.F. 및 local height function을 이용하여 추적하였다. 수치해석 검증을 위하여 수치해석 및 실험 결과와 비교를 수행하였는데 비교적 만족할 수 있는 결과를 확인하였으나 해양구조물 설계시 유용한 결과를 얻기 위해서는 쇄파와 같은 극한파 재현과 극한파에 의한 충격력에 대한 많은 연구가 지속되어야 함을 알 수 있었다.

• Journal of Astronomy and Space Sciences
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• 제36권2호
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• pp.61-68
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• 2019

We have investigated the variations of sporadic E (Es) layer using the measurements of digisondes at Icheon ($37.14^{\circ}N$, $127.54^{\circ}E$, IC) and Jeju ($33.4^{\circ}N$, $126.30^{\circ}E$, JJ) in 2011-2018. The Es occurrence rate and its critical frequency (foEs) have peak values in summer at both IC and JJ in consistent with their known seasonal variations at mid-latitudes. The virtual height of the Es layer (h'Es) during equinox months is greater than that in other months. It may be related to the similar variation of meteor peak heights. The h'Es shows the semidiurnal variations with two peaks at early in the morning and late in the afternoon during equinoxes and summer. However, the semi-diurnal variation is not obvious in winter. The semi-diurnal variation is generally thought to be caused by the semi-diurnal tidal variation in the neutral wind shear, whose measurements, however, are rare and not available in the region of interest. To investigate the formation mechanism of Es, we have derived the vertical ion drift velocity using the Horizontal Wind Model (HWM) 14, International Geomagnetic Reference Field, and Naval Research Laboratory Mass Spectrometer and Incoherent Scatter Radar-00 models. Our results show that h'Es preferentially occur at the altitudes where the direction of the vertical ion velocity changes. This result indicates the significant role of ion convergence in the creation of Es.

• 대한물리치료과학회지
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• 제29권1호
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• pp.47-54
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• 2022

Background: Plyometric exercise is an exercise exerting forceful power in a brief period using isotonic activation. It is effective to improve reaction of muscle, agility, endurance and athletics performance. Weight training is an exericse improving muscular strength, endurance and respirating ability applying diversely in frequency and load of exercise Plyometric exercise and Weight training is to facilitate the athletics performance though improving the function of lower limb muscle, there is a difference that Plyometic jump squats is the way to improve agility and Weight training is the way to improve muscular strength. Therefore, it is necessary to know how this difference effects on athletics performance as measuring ankle, ROM, and jumping ability. Design: Randomized controlled trial. Method: This study was conducted with the voluntary participation of 40 university students, who were randomly assigned to jump squat and calf raise groups (n=20 per group). For each subject, we measured the range of motion of the ankle joint before and after exercise, as well as a standing broad jump and vertical jump test performance. We compared the performance indices before and after exercises using paired t-tests, and between groups using independent-samples t-tests. Conclusions: Both jump squat and calf raise exercises improved ankle joint dorsiflexion and plantar flexion, as well as standing broad jump and vertical jump height performance. However, there were no significant differences before versus after exercise, or between exercise types. Although jump squats and calf raises have different purposes, it is thought that, in combination, these exercises improve performance more effectively than either alone, and that such a combined exercise program improves the quality of training in both the general public and athletes in various sports.

• 한국운동역학회지
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• 제13권3호
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• pp.81-98
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• 2003

The purpose of this study is to closely examine kinematic characteristics by jump phase of Li Xiaopeng motion in horse vaulting and provide the training data. In doing so, as a result of analyzing kinematic variables through 3-dimensional cinematographic using the high-speed video camera to Li Xiaopeng motion first performed at the men's vault competition at the 14th Busan Asian Games, the following conclusion was obtained. 1. It was indicated that at the post-flight, the increase of flight time and height and twisting rotational velocity has a decisive effect on the increase of twist displacement. And Li Xiaopeng motion showed longer flight time and higher flight height than Ropez motion with the same twist displacement of entire movement. Also the rotational displacement of the trunk at peak of COG was much short of $360^{\circ}$(one rotation) but twist displacement showed $606^{\circ}$. Likewise, Li Xiaopeng motion was indicated to concentrate on twist movement in the early flight. 2. It was indicated that at the landing, Li Xiaopeng motion gets the hip to move back, the trunk to stand up and the horizontal velocity of COG to slow down. This is thought to be the performance of sufficient landing, resulting from large security of rotational displacement of airborne and twist displacement. 3. It was indicated that at the board contact, Li Xiaopeng motion made a rapid rotation uprighting the trunk to recover slowing velocity caused by jumping with the horse in the back, and has already twisted the trunk nearly close to $40^{\circ}$ at board contact. Under the premise that elasticity is generated without the change of the feet contacting the board, it will give an aid to the rotation and twist of pre-flight. Thus, in the round-oH phase, the tap of waist according to the fraction and extension of hip joint and arm push is thought to be very important. 4. It was indicated that at the pre-flight, Li Xiaopeng motion showed bigger movement than the techniques of precedented studies rushing to the horse, and overcomes the concern of relatively low power of jump through the rapid rotation of the trunk. Li Xiaopeng motion secured much twist distance, increased rotational distance with the trunk bent forward, resulting in the effect of rushing to the horse. 5. At horse contact, Li Xiaopeng motion makes a short-time contact, and maintains horse take-off angle close to vertical, contributing to the increase of post-flight time and height. This is thought to be resulted from rapid move toward movement direction along with the rotational velocity of trunk rapidly earned prior to horse contact, and little shave of rotation axis according to twist motion because of effective twist in the same direction.

• 한국실내디자인학회논문집
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• 제40호
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• pp.139-148
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• 2003

For lighting design in such diverse structures, we need lots of considerations, such as use and characteristics of the structure, harmony with its surroundings, and the function and type of lighting to be installed. The structural characteristics is determined by its shape and several vertical and horizontal factors based on the shape, which can be focused on at day time by shading, the surface structure, the quality of the surface and the color. On the other hand, they can be at night hidden in the darkness or enforced strongly by the effect of the lighting. In this paper, correlation between the ways of lighting and building facade types according to vocabularies for sensitivity is explored based upon an analysis of building facades for small-scale commerce which plays an important role in cityscape lighting design. It is considered that categorization of types of building facades, presented in this article, and the classification system of exterior lighting methods can be useful in planning lighting. And the process of the study is thought to be able to present a method about the exterior lighting planning. Furthermore, computer simulation on the bases of the correlation model of the lighting methods related to vocabularies for sensitivity about the building facade types is expected to be data and means which can be a great help for designers to predict various results quickly.

• 한국의류학회지
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• 제24권4호
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• pp.530-537
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• 2000

The purpose of this study is to develop the measuring tool that can grasp the relationship between body and pattern, the result can be directly digitalized and developed as the pattern as body form is. There are 6 measurements; 1) the width of front and rear neck 2) the slant degree of shoulder 3) the degree of protrusion of breasts and scapulae 4) the separation of front and rear board 5) space between body and clothes 6) vertical strand in the clothes Developed measuring tool is handy in un. in which points of body to be measured are small, and it has the capability of designing the high fitness for body. The measurer developed through this study is named as $\ulcorner$Somato-pattern Measurer$\lrcorner$, size paper is named$\ulcorner$Somato-pattern Paper$\lrcorner$and the pattern made by$\ulcorner$Somato-pattern Measurer$\lrcorner$is named$\ulcorner$Somato-pattern$\lrcorner$respectively by our team. The result of this study is thought to make a great contribution to solving the various problems which can be derived in the time of pattern design because of the difference of physical forms in the same size as well as the difference between the factor of size and that of form in body.

• 대한치과교정학회지
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• 제22권3호
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• pp.703-713
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• 1992

Researches in pathologic entities and syndromes that describe temporomandibular joint (TMJ) or TMJ-related pain and dysfunction, have been hampered by confusion and conflict over the pathogenesis of myofascial and joint pain, the character and causes of joint noises, and the lack of scientific methods. Investigators have more recently correlated clinical diagnosis and arthrographic and surgical findings to demonstrate 'internal derangements' of the TMJ. It is thought that the structural and functional changes characteristic of internal derangements constitute the principal pathologic entity of the TMJ. Cephalometric data from a group of 34 subjects with documented functional changes in the TMJ were compared with those of a group of 35 subjects from a control sample. The results were as follows: 1. Comparison of a group which shows Class I relationship, there was a tendency to show clock-wise rotation of mandible and linguoversion of upper and lower anterior teeth in the experimental sample. 2. Excluding the vertical relationship, there was a tendency to show low values of the lingual surface slope of the upper central incisor and high values of the interincisor angle in the experimental sample.

• 한국화재소방학회논문지
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• 제18권4호
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• pp.103-109
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• 2004

지하공간에서의 재난은 많은 인명피해를 가져오고 있어서 지하공간에 대한 위험성평가는 인명피해를 최소화할 수 있는 방안으로 우선되어야 한다. 특히 지하철 역사에서의 피난동선과 연기의 이동경로가 동일하여 발생되는 피해를 최소화하기 위한 수직개구부상의 제연경계벽 설치연구는 필수적이며, 화재시뮬레이션을 통한 평가를 통하여 그 효용성을 분석한 결과 연기제어와 피난여유시간을 확보하고 기존 역사에 설치된 제연설비와의 연계된 작동시 많은 효과가 있을 것으로 확인되었다. 이를 통하여 일부 수도권 지하철 역사에는 수직개구부에 제연경계벽을 설치하였고, 계속적으로 위험성평가를 통한 분석을 진행하고 있다.

• Journal of Radiation Protection and Research
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• 제45권3호
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• pp.95-100
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• 2020

Background: Compared with reported data of radon concentration, data of radon progeny concentration is limited in general, especially in outdoor environment. Materials and Methods: To know both the level and the variation of radon progeny concentration in outdoor environment in Beijing area, one-year continuous measurement with a cycle of 60 minutes was carried out by a step-advanced filter (SAF) monitor for radon progeny measurement. The observation site was located in a park in Eastern Beijing area, and the observation period was from October 17, 2018 to September 29, 2019. Results and Discussion: The equivalent equilibrium concentration (EEC) of radon progeny varies from 0.7 to 19.1 Bq·m^-3, with an annual average of 4.9 ± 2.7 Bq·m^-3. A clear diurnal variation of EEC, higher in the early morning and lower in the late afternoon, is observed due to the high sensitivity of the SAF monitor. Conclusion: Vertical convection of atmospheric boundary layer is thought to be the main reason of this phenomenon. For annual variation, the lowest monthly average EEC appeared in April, while the highest appeared in November, which might attribute to the atmospheric stability in different seasons.

• 한국기계가공학회지
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• 제11권4호
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• pp.160-167
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• 2012

This paper is concerned with a particular fracture mechanics parameter ${\Delta}K_{th}$, known as the 'threshold stress intensity range', or 'fatigue threshold'. This threshold ${\Delta}K_{th}$ constitutes, as it were, a hinge between the notion of crack initiation and the notion of crack growth. It has often been thought that, like the endurance limit, it could be an intrinsic criterion of the material. The study was conducted on a SA-508 pressure vessel steel used in the nuclear power industry. This material exhibits a typical threshold effect in the range of the crack growth rates which were determined; that is, below approximately $da/dN=10^{-6}mm/cycle$, the slope of the da./dN versus ${\Delta}K$ curve is almost vertical. The value of ${\Delta}K_{th}$ was determined at a growth rate of $10^{-7}$ mm/cycle according to the ASTM Standard for threshold testing. The fatigue threshold values are in the range 21 $kg/mm^{3/2}$ to 12 $kg/mm^{3/2}$ depending on the stress ratio effect.