In order to investigate the environmental properties of set net grounds located in the coastal waters of Yeosu, oceanographic observations on the fishing grounds were carried out by the training ship of Yeosu Fisheries University from Jun. 1988 to Dec. 1990. The resultes obtained are summarized as follows; 1) The water mass in the fishing grounds were divided into the inner water (29.50-31.00‰), the mixed water (31.10-32.70‰) and the offshore water (32.70-34.30‰) according to the distribution of salinity from T-S diagram plotted all salinity data observed from Jun. 1988 to Dec. 1990. In spring the mixing water prevailed and in summer the inner and mixing water. But in autumn and winter the mixing and offshore waters prevailed. 2) The inner water which was formed by land water from the river of Somjin and the precipitation in the Yeosu district flowed southerly along the coast of Dolsando and spread south-easterly in the vicinity of Kumodo. The inner water and offshore water which supplied from the vicinity of Sorido and Yokchido formed the thermal front and halofront. 3) As the mixing water flowing from the western sea of Cheju to the southern coast of korea was low in temperature, the water mass of low temperature which appeared at the offshore bottom of Sorido in summer was considered not to be the Tsushima warm current. 4) As vertical mixing was made frequently in spring, autumn and winter, the differences in temperature and salinity between surface and bottom was respectively small. In summer, however, the mixing was not made because of the inner water expanded offshore through the space between surface and 10m layer and so a thermocline of 2.0℃/10m and halocline of 4.0‰/10m respectively in vertical gradient was formed. 5) In the vicinity of Dolsando and Kum a water low in salinity prevailed, but in the vicinity of Namhaedo and YoKchido the reverse took place. The inner and mixing waters formed at these arease was limited to the observation area not to spread widely.
The purpose of this paper is to study the subject of economic evaluation in respect of optimum ship size and basic design spiral for fishing vessels. The main ta나 is developed the methodology of engineering economic system in order to apply various methods and tools which may be utilized by the designer in his efforts to arrive at principal design characteristics of fishing vessels with optimum size. The design procedure has been modeled in mathematical form with CBR as an criteria and applied to the optimization method. The contents of the study are as follows (the special treatises).
한국의 연안어선에 장비된 소형자기컴퍼스의 장비현황과 성능을 연구하기 위하여 소형어선 219척의 선박제원과 자기컴퍼스 이용에 대한 현장 설문조사를 행하고, 그 중에서 총톤수 4-6톤급의 실험대상 어선 4척을 선정하여 그 선박의 자기컴퍼스의 설치위치별 자차측정과 성능실험을 행하고, 이를 검사, 조사하였다. 주요한 결과를 요약하면 다음과 같다. 1. 조사 대상으로 한 총톤수 1-10 톤급 연안어선 219척 중 4톤 미만의 어선은 약 50%를 차지하였고, 자기컴퍼스의 제작연도가 20-30년 경과된 어선이 14척이나 되었으며, 자차수정용구를 비치한 어선은 2척 뿐이었다. 2. 컴퍼스의 설치위치별로 측정된 자차를 분석한 결과, 기관실위의 브리지갑판상과 브리지내의 컴퍼스받침대위 및 브리지위의 컴퍼스 갑판상에 자차수정을 한 자기컴퍼스를 설치하여 사용하면, 브리지내의 컴퍼스대의 위와 브리지위의 컴퍼스 갑판상에서는 잔재자차가 ±1~2 ˚ 정도였으나, 기관실 위의 브리지갑판상에서는 그 잔재자차가 ±5 ˚로 이곳은 컴퍼스 설치 장소로서 부적당함을 알 수 있었다. 3. 연안어선에서 사용 중인 자기컴퍼스의 제반특성은 표준규격인 반주기의 평균치가 12초 이상이어야 하고, 3회 이상 진동해야하는 기준에 미달하였으며, 측정치인 자기능률 1400 CGS는 소형컴퍼스의 표준치 400±30 CGS와는 큰 차이가 있었다. 4. 실험 대상 어선에 장비하고 있는 자기컴퍼스의 수반각은 6~16 ˚로서 한국표준규격인 1~1.5 ˚에 비해 너무 크게 나타나 그 표준규격에 부적합한 것으로 판단되었다.
예연소실식 디젤기관에 있어서 박용부하운전조건에 따른 연소특성을 규명하기 위해 예언소실의 압력데이터를 single-zone, single-chamber의 열역학적 해석에 적용하여 연소해석을 행한 결과 다음과 같은 결론을 얻었다. 1) 부하가 증가함에 따라 최고압력이 상승하고 그 위치가 크랭크각도상 후진되었다. 2) 착화 지연시간은 부하에 관계없이 거의 일정하고, 부하가 증가할수록 가연 혼합기 형성에 소요되는 흡열량은 겉보기로 감소하였다. 3) 예혼합 연소단계의 열발생 양상은 부하에 관계없이 거의 비슷하고, 예혼합 연소시간은 부하가 증가할수록 짧아졌다. 4) 부하가 증가함에 따라 예혼합 연소량은 다소 증가하나 일정 연공비 이상에서는 거의 일정했다. 5) 예혼합 연소분율은 부하가 증가함에 따라 감소했다.(이 논문의 결론부분임)
Modal Analysis is the process of characterizing the dynamic properties of an elastic structure by identifying its modes of vibration. A mode of vibration is a global property of an elastic structure. That is, a mode has a specific natural frequency and damping factor which can be identified from response data at practically any point on a structure, and it has a characteristic mode shape which identifies the mode spatially over the entire structure. Modal testing is able to be performed on structural and mechanical structure in an effort to learn more about their elastic behavior. Once the dynamic properties of a structure are known its behavior can be predicted and therefore controlled or corrected. Resonant frequencies, damping factors and mode shape data can be used directly by a mechanical designer to pin point weak spots in a structure design, or this data can also be used to confirm or synthesize equations of motion for the elastic structure. These differential equations can be used to simulate structural response to know input forces and to examine the effects of pertubations in the distributed mass, stiffness and damping properties of the structure in more detail. In this paper the measurement of transfer functions in digital form, and the application of digital parameter identification techniques to identify modal parameters from the measured transfer function data are discussed. It is first shown that the transfer matrix, which is a complete dynamic model of an elastic plate structure can be written in terms of the structural modes of vibration. This special mathematical form allows one to identify the complete dynamics of the structure from a much reduced set of test data, and is the essence of the modal approach to identifying the dynamics of a structure. Finally, the application of transfer function models and identification techniques for obtaining modal parameters from the transfer function data are discussed. Characteristics on vibration response of elastic plate structure obtained from the dynamic analysis by Finite Element Method are compared with results of modal analysis.