Towing tension of the model nets were determined by the load cell(O~20kg, 20DBBP) in front of W〈lrp with the combinations of towing velocity, warp length and the distance between paired boats. Towing tension of the full scale net was determined by the load cell( 0 ~ 6ton) in front of warp with the towing velocity. The results obtained can be summarized as follows; 1. The changing aspect of towing tensions of the model nets A and B varied by the same tendency in the range of O.356-2.019kg and O.352~2.117kg, respectively, depend on the operational factors. Among the factors, the towing velocity was the most influential. The tensions(T) can be expressed as a function of the towing velocity(V) as TmA = 1.57 . V1.86 (unit: kg, mlsec) TmB= 1.58 . V1.90 2. The towing tension of the full scale net was almost coincided with the results obtained by the model experiment. The towing tension(T) can be expressed as a function of the towing veJocity(V) as T=479V1.75(unit: kg, k't)
Full scale experiment was carried out in the southern sea of Korea to compare some important factors tested in the model experiment. The results obtained can be summarized as follows ; 1. The changing aspect of mouth performance of the full scale net was almost coincided with the results obtained by the model experiment. The vertical opening(H) and the opening area(S) can be expressed as a function of the towing velocity(V) as H=48.78. e0.38V(unit: m, k't) S= 1,443 .e-0.25V(unit: m2V, k't) 2. The changing aspect of working depth of the full scale net was almost coincided with the results obtained by the model experiment. The depth(D) can be expressed as a function of the towing velocity(V) and the warp length(L) as D=92.49.V1.37(unit: m, k't, L= 150m) D= 12.07+0.32. L (unit: m, V=2k't) [)= - 7.90+0.22 . L (unit: m, V=3k't) 3. Some problems were found to operate A - type full scale net by common bottom pair trawlers. The problems can be summarized as follows; (1) Entangling of wing and square head ropes while net casting.(2) Man power needed and time spent for net hauling by common bottom trawlers increased considerably.( 3) Tearing of nettings caused by over -load of tension and entangling of net pendant while net hauling. To solve these problems, the trawlers are favorable to be equipped with variable pitch propeller and llet drum. While the net is favorable to be constructed with trifurcated net pendant in stead of quadrifurcated net pendant used at present.
Spatial distribution characteristics, volume backscattering strength and species composition of midwater trawling catch was analyzed biological and acoustical characteristics of anchovy shoal, using a high resolution echo - sounder at the south region of East sea of Korea. 1) In the survey site A of Lat.35˚55'N, Long.129˚45'E, the anchovy shoal of small to middle size with the horizontal range of 10~25m and large size with the horizontal range of 40~50m were distributed together. However in the survey site B of Lat.35˚38'N, Long.129˚40'E, the anchovy shoal was observed to be mainly small size which about 78% of the detected shoal. Another was that the anchovy shoal with the vertical range of 2~8m occupied about 68.6% in the survey site A and that of 6~12m occupied about 42.5% in the survey site B. The mainly the site A and B were found to be 10~50m super (2), 64.5% and 20~80m super (2), 66%, respectively. 2) The volume backscattering strength in the site A and B were observed to be -44.0~ -28.0dB, respectively. In the site A, the backscattering strength of -40.0~ -30.0dB was analyzed about 41.4%. 3) Most of total anchovy shoal was concentrated in the water layer of 50~100m in depth with 15.3~18.5℃, 34.0~34.3‰ in the survey site A and 14.2~16.4℃, 34.1~34.2‰ in the survey site B. 4) Mean total length(TL) and body weight(BW) of anchovy in the survey site A were 9.9cm and 4.4g respectively, with TL-BW relationship of BW=0.0007TL3.65super (3.85). In site B, mean total length(TL) and body weight(BW) were 11.2cm and 8.7g, with TL-BW relationship of BW=0.0023TL3.36.
This paper described on relation between the catches of tuna and the distribution of water temperature of eastern fishing ground of Tropical region in the Pacific Ocean. The data of catches and water temperature used in this paper were based log book which # 27 CHENG RONG(Gross tonnage : 399 ton) had been worked eastern fishing ground(Lat : 09˚N- 14˚S, Long : 115˚- 149˚W)from January to October, 1991. The obtained result are as follows : 1. On the relation between the catches and the geographical distribution, bigeye tuna was higher catches at Lat 4˚- 9˚N, Long 135˚- 139˚W area in the equatorial counter current region where surface water temperature was range of 27.5℃ to 27.9℃, yellowfin tuna was higher catches at Lat 4˚- 9˚S, Long 145˚- 149˚W in the south equatorial current region where surface water temperature was range of 28.0℃ to 28.4℃ and albacore tuna was higher catches at Lat 10˚- 14˚S, Long 120˚- 124˚W area in the south equatorial current region where surface temperature was range of 26.5℃ to 26.9℃ 2. On the relation between catches and distribution of vertical water temperature, bigeye tuna was higher catches at the water temperature of 10℃ to 12℃ on depth layer between 300m and 360m, yellowfin tuna was higher catches at the water temperature of 15℃ to 19℃ on depth layer between 180m and 280m and albacore tuna was higher catches at the water temperature of 12℃ to 14℃ on depth layer between 280m and 310m. Above the result, it seemed that bigeye tuna distributed deeper layer than yellowfin and albacore tuna.
The author examined the response of Armorclad rockfish, Sebastes hubbsi [MATSUBARA]to the surface attracting lamps (0.5W, 0.8W, 1W) line in the experimental water tank (550L×58W×73Hcm). The attraction rate was investigated in accordance with the intervals of lighting and putting out hour (1,5 minute) when each of the attraction lamps was gradually switched off after they were switched on all at once. The results are as follows : 1. Total distribution rate of fish in the illuminated section was 61.6%(mean 12.3%) in case of 1 minute interval, and 41.0%(mean 8.2%) in case of 5 minutes interval. 2. Mean distribution rate of fish at the illuminated section : ①Distribution rate at interval of 1 minute were 12.7% in 0.8W, 12.4% in 0.5W and 11.9% in 1 W respectively. ②Distribution rate at interval of 5 minutes were 9.0% in 1W, 8.6% in 0.8W and 7.0% in 0.5W respectively. 3. Attraction rates of the last section showed a little increasing as illuminating time elapsed. A difference of attraction rates according to lighting source in 1 minute interval was bigger than that in 5 minute interval. 4. Attraction rate of fish in only last section switched on : ①Attraction rate at interval in case of 1 minute were 52.0% in 0.8W, 46.7% in 0.5%W and 45.3% in 1W respectively. ②Attraction rate at interval in case of 5 minutes were 32.0% in 1W, 24.0% in 0.8W and 14.7% in 0.5W respectively.
The authors carried out a field experiment to confirm the effect of underwater sound on the luring of fish schools in a setnet in the coast of Cheju Island. The effects of the acoustic emission on the luring of fish schools were observed using a manufectured underwater speaker in the setnet, and pure sound, of which frequency was 600Hz and the source level was 126dB, was emitted on and off at 5 minutes intervals in the set net during the night of ,July 29 and ,July 31. So we had recorded behavior of fish schools by the telesounder with two channel and shape of the setnet by underwater video camera and analyzed them. When the flood and ebb currents were around the setnet, the nets rised to the surface of water and it happened occasionaly at the stand of tide. Therefore, it was in the state that fish schools feel constraint to enter into the setnet, and was required a new design of the setnet stand up to strong tidal current. As the pure sound, of which frequency was 600Hz was emitted for the luring of fish schools in a setnet, the catch ammounts of fish, the young horce mackereWI'rachllrlls japonicus), was increased 4~6 times than not emitted.
This paper considers robust stability and transient behavior of the Two - Degree - of - Freedom(2DOF) servosystem. A class of uncertainties allowed in the plant model is obtained, to which the servosystem is robustly stable for any gain of the integral compensator. This result implies that if the plant uncertainty is the allowable set defined by the condition, a high - gain compensation can be carried out preserving stability to achieve a high - speed tracking response. The transient behavior attainable by the limit of the high - gain compensation is calculated using the singular perturbation approach.
The heat transfer performance of R - 11 vapor condensing on integral fin tubes has been studied using fin tubes having the fin density from 748 to 1654 fins per meter. Electric heater supplied heat energy to the boiler to generate R - 11 vapor over the range of 25-60W. Condensation rates of each tubes were tested under the condition of cooling water flow rate from 400l/h to 2500l/h. For the seven fin tubes tested, the best performance has been obtained with a tube having a fin density of 1417fpm and a fin height of 1.3mm. This tube has yielded a maximum value of the heat transfer coefficient of 16500W/m2K, at a vapor to wall temperature difference of 3K. Experimental results of integral fin tubes have been compared with available predictive models such as Beatty - Katz's analysis, Webb's analysis, Sukhatme's analysis and Rudy's empirical relation. The experimental results were shown to be in good agreement with that of the Sukhatme's analysis.
Recently, the fact that welding conditions are dangerous for men and the shapes of seams are complex enforced the welding system to be automatic. In order to obtain this target, are chip Microprocessor controlled welding system is devised in this study. The tracking of seam shape is achieved by applying a differential transformer and by using a program developed. This welding system mainly consists of a sensor, the differential transformer, a servo power amplifier, a control system, and DC motors. It is verified that the developed welding system is able to track three kinds of seam shapes.
In the elM construction of naval architecture industry, ship hull surface modeling is critical process of design/manufacture process. This paper describes a fairing process of ship waterlines to represent boundary curves which are input data of surface modeling. Among the fairing methods, Sapidis's method and Rong's method are used in sequential to fair the boundary curves. Also it proposed four methods of determining the magnitude of end tangent vector. Among the four end tangents the best one is chosen by comparing with the shape of near curves. An application to the actual ship hull is given as an example.
2단계 접속 논리(two-stage cascaded logic)는 관측 지역 내에 새로이 출현한 표적에 대한 트랙을 만드는 대표적인 방법중의 하나이다. 2단계 접속 논리의 트랙 생성 (track formation)에 관한 성능 평가 방법 및 결과는 Bar-Schalom에 의해 발표된 바가 있으나, 그 연구 결과는 트랙 생성 성능을 도출할 때 클러터로 인한 오경보율(false alarm probability)을 무시한다는 가정에 기초한 것이기 때문에, 오경보율이 높은 경우에는 적용 할 수 없다는 단점을 지닌다. 이에 본 논문에서는 오경보율을 고려하여 2단계 접속 논리의 트랙 생성 성능을 평가 할 수 있는 개선된 방법을 제시하고자 한다. 그리고 2단계 접속 논리에서 사용하는 데이터 연관(data association)기법으로 트랙 분리(track splitting)기법과 최 근접 데이터 선택 기법(nearest neighbor rule)을 사용하는 경우에 대하여 각각의 성능 평가 결과를 몇 가지 예시하고자 한다.
반도체 소자에 정전기 방전으로 인한 소자내의 온도 상승을 알기 위해 열전달 방정식으로부터 열모델을 유도하였다. 그리고 열파괴 문턱전류를 얻고 시간에 따른 온도 변화를 열모델로부터 해석하였다. 여기서 유도한 열모델은 Wunsch-Bell모델에 지수 항을 추가한 형태이다. 이 모델의 유효성을 증명하기 위해 실험결과와 비교한 결과 매우 잘 일치하였으므로 이 열모델의 함수는 입력보호회로의 반도체소자를 설계하는데 매우 유용하다.