• 한국강구조학회 논문집
• /
• 제23권6호
• /
• pp.763-775
• /
• 2011

경사진 평행 병렬 사장재 케이블의 웨이크 갤로핑 발현 특성을 2차원 부분모형을 통하여 규명하였다. 경사진 병렬 사장재를 모사하기 위하여 두 실린더를 나란히 경사배치 하였으며 중심간격 변화에 따른 풍상측 및 풍하측 실린더의 진동을 관찰하였다. 실린더 지름의 여섯 배까지 케이블강교량설계지침의 허용값을 초과하는 진동이 관할되었다. 이는 설계 시 관용적으로 사용되는 검토기준이 비교적 적정함을 의미하는 것이다. 반면, 감쇠의 증가는 웨이크 갤로핑의 발현을 억재하는 데 효과적이지 않음을 확인할 수 있었다.

• 한국정밀공학회지
• /
• 제17권7호
• /
• pp.113-123
• /
• 2000

In the navigation for a mobile robot, the collision avoidance with unexpected obstacles is essential for the safe navigation and it is independent of the technique used to control the mobile robot. This paper presents a new collision avoidance algorithm using neural network for the safe navigation of the autonomous mobile robot equipped with CAN and ultrasonic sensors. A tracked wheeled mobile robot has a stability and an efficiency to move on a rough ground. And its mechanism is simple. However it has difficulties to recognize its surroundings. Because the shape of the tracked wheeled mobile robot is a square type, sensor modules are generally located on the each plane surface of 4 sides only. In this paper, the algorithm using neural network is proposed in order to avoid unexpected obstacles. The important character of the proposed algorithm is to be able to detect the distance and the angle of inclination of obstacles. Only using datum of the distance and the angle, informations about the location and shape of obstacles are obtained, and then the driving direction is changed. Consequently, this algorithm is capable of real time processing and available for a mobile robot which has few sensor modules or the limited sensing range such as a tracked wheeled mobile robot. Effectiveness of the proposed algorithm is illustrated through a computer simulation and an experiment using a real robot.

• 대한기계학회논문집B
• /
• 제25권8호
• /
• pp.1103-1112
• /
• 2001

The effect of pressure gradients on the hairpin structures in three different turbulent boundary layers (ZPG : Re(sub)$\theta$=910, FPG : Re(sub)$\theta$=575, APG : Re(sub)$\theta$=1290) has been examined with instantaneous velocity fields obtained in streamwise-wall-normal planes using PIV (particle image velocimetry) method. In the outer layer hairpin vortices occur in streamwise-aligned packets that propagate with small velocity dispersion. The signature pattern of the hairpin consists of a spanwise vortex core located above a region of strong second quadrant fluctuation (u<0 and v>0 : Q2 event) is clearly observed. The formation of packets explains the occurrence of multiple VITA events in turbulent burst. Noticeable differences are found in the average inclination angles of hairpin vortex packets which are 45$^{\circ}$, 35.7$^{\circ}$, and 51.9$^{\circ}$in the case of ZPG, FPG and APG, respectively. It is found that the large, time-varying, irregularly shaped zones with nearly constant streamwise momentum exist throughout the boundary layer. Within the interior of the envelope the spatial coherence between the velocity fields induced by the individual vortices leads to strongly retarded streamwise momentum, explaining the zones of uniform momentum. The formation of the uniform momentum zone is remarkably different with respect to the pressure gradients especially in the logarithmic layer.

• 농촌계획
• /
• 제24권3호
• /
• pp.33-42
• /
• 2018

The aim of our study was to provide a basic data for the development of a small greenhouse model suitable for urban farmers. The study analyzed installation inclination, positive and negative reasons for installation, location of installation, preferred crops in small greenhouses, plans for use of products, and expected effects by using small greenhouse. Positive opinion on small greenhouse installation was 80.4% of the survey respondents. The most positive reason for the installation of small greenhouses was fresh and safe food supply, and the negative reason was maintenance difficulties. The results obtained in our survey indicated that small greenhouses were more likely to be installed near the house, and urban farmers tended to grow organic leafy vegetables in soil. The expected benefits of small greenhouse operation were largely divided into 'benefit for the improvement of the quality of life' and 'benefit for economic profits', and expectation for the improvement of the quality of life was higher than economic benefit. As a result of the Likert 5-point scale analysis, 'benefit for the improvement of the quality of life' by using a small greenhouse was graded as high as 4.17~4.60. On the other hand, the 'benefit to economic profits' was rated as low as 3.51~4.14.

• 한국운동역학회지
• /
• 제19권4호
• /
• pp.761-770
• /
• 2009

이 연구는 엘리트 110m 허들선수의 세 번째 허들 넘는 동작에 관한 자세의 기술적 특징을 운동학적으로 비교분석하였다. 연구대상자는 국내에서 개최된 110m 허들의 제3회 국제육상경기대회에서 상위 입상한 전 세계기록 보유자인 국외선수 2명과 국내선수 1명으로 선정하였다. 허들을 넘는 동작인 허들링 동작의 자세에 대한 기술적 요인을 분석하기 위해 신체분절의 각도를 조사한 결과 다음과 같은 결론을 얻었다. 국외선수는 국내선수에 비해 도약과 착지 순간 신체중심각도가 전 세계기록 보유자인 국외선수는 평균 $34.14^{\circ}$, 국내선수는 $24.89^{\circ}$로 신체중심각도의 이동범위가 크게 나타났다. 상체전경각도는 도약과 착지 순간 전 세계기록 보유자인 국외선수가 $4.27^{\circ}$, 국내선수가 $6.37^{\circ}$로 전 세계기록 보유자인 국외선수 상체의 상하 움직임이 작은 것으로 나타났고, 상체좌우각도는 도약과 착지 순간전 세계기록 보유자인 국외선수가 $3.18^{\circ}$, 국내선수가 $11.58^{\circ}$로 전 세계기록 보유자인 국외선수 상체의 좌우 움직임이 작은 것으로 나타났다.

• 한국항공우주학회지
• /
• 제33권8호
• /
• pp.92-98
• /
• 2005

스크린은 유동저항을 일으켜 유동의 난류, 속도 및 압력 특성을 변화시킬 수 있으며, 이에 따라 유동제어 방법으로 널리 사용되어 왔다. 과거 관련 분야 연구들은 마하수가 0.3에서 0.7 사이의 유동에 제한되어 왔고, 초음속 유동에서 나타나는 충격파 구조에 대한 연구는 수행되어진 바 없다. 따라서 본 연구에서는 철선으로 엮어진 스크린 후방에서 나타나는 축대칭 초음속 제트유동장에 대한 실험적 관찰이 이루어졌다. 다양한 제트유동 팽창조건에 대하여 스크린 후방에서 연속 및 순간광원을 이용한 쉴리렌 유동가시화와 피토압력/유동소음 측정이 이루어졌다. 노즐 출구에 설치된 스크린의 다공도와 설치 기울기 변화에 따른 영향도 관찰되었으며, 얻어진 결과는 스크린이 설치되지 않은 경우와 서로 비교되었다.

• 한국지역지리학회지
• /
• 제18권2호
• /
• pp.129-140
• /
• 2012

제주도 폭포의 지형 특성을 파악하기 위하여 한라산 산록과 서귀포 해안지대에 소재하는 26개 폭포를 대상으로 용암류의 형태와 물리적 성질에 의해 폭포를 분류하고, 후퇴프로세스를 검토하였다. 폭포벽과 폭호를 구성하고 있는 용암류 유형과 매수에 근거하여 단일 용암류형, 복수 용암류형, 기저부 연암형 및 용암류 암괴형으로 유형화할 수 있다. 단일 용암류형 폭포는 조면암이나 조면안산암 분포지역에, 복수 용암류형 폭포와 기저부 연암형 폭포는 현무암이 나 조면현무암 분포지역에 잘 발달하여 폭포 유형에 용암류의 암질이 반영되고 있다. 폭포의 후퇴프로세스는 단일 용암류형 폭포에서는 감경사적 후퇴나 교체후퇴가 나타나는 반면 기저부 연암형 폭포는 전형적인 평행후퇴를 한다. 복수 용암류형 폭포는 용암류의 물리적 성질에 따라 세 후퇴 유형을 모두 보인다. 수직절리가 잘 발달한 용암류가 폭포벽을 만들고 있으므로 대부분의 폭포는 수직에 가까운 폭포벽을 지닌다.

• 한국의류학회지
• /
• 제28권6호
• /
• pp.746-757
• /
• 2004

This study was intended to analyze clothing preference images according to the age groups (30's, 40's, 50's and 60's) and to clarify the differences between present clothing preference images and that of the future after 60. The data was collected through a questionnaire and a total of 482 questionnaires on the age groups ranging from 30s through 60s were used in the analysis. As for the present clothing preference images in accordance with age groups, the younger age groups in the range of 30's and 40's presented higher scores in most of these images. But the older age groups in the 50's and 60's had lower scores in most of these images. On the contrary, the older age groups had higher scores than the younger age groups with respect to similar, mature, magnificent, innocent, plump and virtuous images. As for the future clothing preference images after 60 in the elegant, luxurious, graceful, intellectual, chic, urbane, slimy and sociable images, the age groups in the 30's and 40's presented higher scores than the age groups in the 50's and 60's did. However, with respect to the youth-oriented images such as fashionable, innocent, remarkable, cute and vigorous images, the age group in the 60's had a higher score than the age group in the 30's, 40's and 50's did. There were differences between the present clothing preference images and future clothing preference images after 60. The 30's and 40's presented distinctively different clothing preference images in the present and future after 60. Thus, distinct images were pursued in the older age group. The 50s showed closest images to that of the older age group, presenting more conservative inclination in clothing preferences.

• 한국해안·해양공학회논문집
• /
• 제27권3호
• /
• pp.182-189
• /
• 2015

ESA는 석션파일에 의해 설치되는 영구적인 해양구조물기초의 한 형태이다. 인발에 대한 정착하중을 증가시키기 위해, 3개의 수직플랜지가 120도의 간격으로 앵커표면을 따라 부착되어있다. ESA 거동에 영향을 미치는 여러 매개변수의 영향을 찾기 위해 고안된 분석적 해법을 이용한 분석적 매개변수 연구가 이루어졌다. 분석의 결과는 앵커의 매입깊이와 흙의 강도가 증가할 때 ESA의 부담하중도 증가하는 것으로 나타났으며, 그리고 하중 경사각이 증가할 때는 감소하는 것으로 나타났다. 또한 사각형의 투영된 면적을 가진 ESA는 앵커길이의 중심에서 수평적으로 인발될 때 가장 큰 인발력을 갖는 것으로 나타났다.

• 한국의류학회지
• /
• 제28권2호
• /
• pp.270-279
• /
• 2004

The purpose of this study is to make a basic resource in developing a design satisfying male consumers＇ fashion inclination by examining the features of the men＇s fashion style shown in the fashion collections. Collected were 1,291 photos relating to the suit style through the analysis on the men＇s fashion collections for 8 years(1995-2002). Representative men＇s fashion images are extracted from these photos, then figurative features were analyzed and typified according to image, and finally representative fashion styles were presented and its meaning was analyzed. Representative men＇s fashion images are Sophisticated, Casual, Elegant, Active, Natural, Classic, Romantic, Ethnic, Military, Marine, Colonial, and Avant-garde. With the subcategories such as detailed shape of jacket and trousers, the relationship of color between upper and lower clothes, type and organizing method of material quality, type and arranging method of pattern, and coordination, the extracted fashion images were analyzed the figurative features. After finding out the common and different features, four men＇s fashion styles were suggested. Formal style maintains the typical suit style and has the feature expressing the men＇s authority, tradition, and honor. It includes Sophisticated, Elegant. and Classic image. Casual St Sporty style has the feature that there is a change in the volume of suit by adding activity to the typical suit style. It includes Casual, Active, and Natural image. Uniformed style is that political and social environment such as war has an influence on the suit design. It includes Military, Marine, and Colonial image. Deformed style has the feature that it suggests new type instead of adhering to the typical suit design. It includes Ethnic, Romantic, and Avant-garde image.