• Ocean and Polar Research
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• 제23권3호
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• pp.279-284
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• 2001

The natural high productivity of temperate coastal waters in Korea can be used in advantage to reduce the feed costs for the cage-cultured marine carnivorous fish species. By using the night-lights methods an alternative of supplementary feeding strategy can be offered to the cage farmers and maintain sound environmental conditions that could enhance maximum sustainable yields. The aim of this study was to investigate the effects of night-lights which shown positive results on feeding and growth in sea cage cultured rockfish, Sebastes schlegeli. The study showed that for the water around overhead illuminated sea cage, higher zooplankton density was observed at night than during the daytime. Increased amounts of for-age, evidenced by stomach content analyses were observed in the early evening, but decreased amounts were observed in the morning and afternoon. That is, feeding activities of the fish were most intensive from midnight to dawn. In a three month feeding experiment, the results showed that night-lighted groups were superior to groups with the highest feeding efficient. This study suggested that the evidence that night-lights superimposed on only day-lights enhance growth of rockfish in sea cages during summer and winter, with timing of exposure affecting growth of juvenile fish. The capability to control the feeding behavior of marine life via manipulation and external stimuli could considerably benefit the advancement of sea cage aquaculture in coastal areas.

• ALGAE
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• 제36권1호
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• pp.51-60
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• 2021

The sea urchin, Mesocentrotus nudus, is widely distributed in North West Pacific regions. It has a substantial impact on macroalgal communities as a generalist herbivore. This study examined various aspects of its feeding ecology, including algal preference, foraging behaviors, and possible effects of past feeding history on its algal preference. We used six common algal species (Ulva australis, Undaria pinnatifida, Sargassum confusum, Dictyopteris divaricata, Grateloupia elliptica, and Grateloupia angusta) from the east coast of Korea as food choice in a series of indoor aquarium experiments. The first choice of starved M. nudus was exclusively U. pinnatifida, followed by G. elliptica and S. confusum. Unlike large urchins, small urchins equally preferred U. pinnatifida and G. elliptica. On the other hand, Undaria-fed urchins preferred to feed only G. elliptica, although its preference slightly differed over time. We then grouped sea urchins into three categories (starved, Undaria-fed, mixed species-fed) to observe 12-days feeding preference as well as early foraging movements. Foraging behaviors of the three groups were distinctively different, although they could not completely reflect the actual consumption. For example, U. australis was highly attractive, but rarely eaten. Undaria-fed urchins seemed to stay with only S. confusum and U. australis. This study demonstrates that M. nudus shows high flexibility in food preference depending on past feeding history and body size. Its foraging behaviors are also affected by past feeding conditions, exhibiting active chemoreceptive movements.

• The Korean Journal of Ecology
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• 제27권6호
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• pp.383-390
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• 2004

본 연구는 1999년 3월부터 2002년 9월에 걸쳐 경기도 시화호, 경기도 웅진군 동${\cdot}$서만도, 장구엽도 3곳에서 검은머리물떼새의 번식기전 행동, 텃세권 행동, 번식생태, 주요 섭식지역과 섭식행동, 종내와 종간번식 및 먹이경쟁에 대해 조사하였다. 검은머리물떼새의 번식 시작은 지역에 따라 차이를 보여 시화호 지역은 4월 중순부터, 동${\cdot}$서만도와 장구엽도의 경우 5월 중순 번식을 시작하였다. 번식에 들어가기 전 짝간의 유대를 강화하기 위한 행동으로 암수짝간의 섭식행동(foraging behavior)과 추적행동(male-female chasing behavior)을 보인다. 교미행동에 들어가기 전 암수는 함께 섭식행동을 하며, 다른 쌍이나 개체들이 섭식장소로 접근해 오면 삑- 삑- 하는 울음소리(piping calling)와 함께 공격적 행동을 보이며 침입자를 쫓아내거나, 침입자 추적비행을 하기도 한다. 연속적 행동양상을 관찰하지 않으면 암수 추적비행과 침입자 추적비행을 구별하기 어렵다. 텃세권 행동은 나비비행(butterfly flight), 음성행동(calling behavior), 침입자 추적행동(chasing behavior), 싸움행동(fight behavior)의 4가지 타입으로 분류하였다. 시화호 지역의 중요 취식 지역은 대부도 선착장 앞쪽, 방어머리 갯벌, 시화방조제 오이도 초입부의 정치망이 설치되어 있는 갯벌, 공단의 조류 조망대 앞쪽 북측 간석지 등 크게 4지역으로 구분된다. 섬지역 중 동${\cdot}$서만도는 썰물시 갯벌에서, 만조시에는 섬 주변에서 취식하였고, 밀${\cdot}$썰물의 차가 없는 장구엽도의 경우 섬 주변에서 주로 취식하였다. 섭식행동 중 종내(intraspecific)와 종간 (interspecific) 경쟁이 이루어졌다. 취식지역에서 검은머리물떼새 개체간에는 먹이를 빼앗기 위해 쫓아가는 행동이 관찰되기도 하고, 중요 취식지역에 다른 개체가 들어올 경우 침입자 추적행동을 하며 쫓아내기도 하였다. 종간 섭식 경쟁은 주로 괭이갈매기와 일어난다. 괭이갈매기와 먹이경쟁이 이루어질 경우에 검은머리물떼새는 먹이를 갈취 당하거나 공격을 받아 다른 지역에서 먹이를 취식하는 개체보다 먹이 섭취율이 상대적으로 떨어지는 것이 관찰되었다. 종간 경쟁이 심하면 섭식지역을 떠나 다른 지역으로 이동하였다.

• 한국생산제조학회지
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• 제22권3호
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• pp.380-387
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• 2013

In this study, two finite element (FE) models were developed to evaluate the thermal characteristics of a feeding axis of a CNC lathe. One was used for analysis of heat transfer to identify the temperature distribution of the feeding axis and then, the other was used for analysis of thermal deformation to evaluate its structural behavior based on the temperature distribution. The FE models were based on the test standard for the axial thermal displacement. The feeding velocity was composed of three steps: the ascending, constant, and descending velocities. Therefore, the heat generation and convection coefficient were calculated for each velocity and applied to the thermal FE model. The convection coefficient for the ball screw rotation was based on an experimental equation. The result of the analytical thermal displacement was compared with that of the experimental displacement to verify the finite element models.

• 생태와환경
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• 제51권2호
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• pp.184-191
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• 2018

섭금류인 검은머리물떼새(Haematopus ostralegus osculans)는 주로 조수 경계부를 섭식지로 이용하는데, 번식기에는 간조시 드러난 갯벌에서 섭식하는 개체들이 일부 관찰된다. 드러난 갯벌에서 섭식하는 경우 조수 경계부에 비해 걸음수가 더 많고, 먹이탐색을 위해 중복탐침과 찔러넣기 행동의 비율이 더 높았지만, 섭식성공률은 현저히 낮았다. 또한, 주요 먹이원은 드러난 갯벌에서는 갯지렁이류였지만, 조수 경계부에서는 복족류(서해비단고둥)와 이매패류로 섭식지 유형간 뚜렷한 차이가 있었다. 번식기에 국한하여 드러난 갯벌을 섭식지로 이용하는 현상은 본래 선호하는 섭식지에 비해 효율이 떨어지더라도 번식 성공을 위해 번식지와 가까운 지역을 섭식지로 이용하는 것으로 판단된다. 본 연구는 번식이라는 생활사 변화에 맞춰 검은머리물떼새가 섭식행동과 먹이원을 달리함으로써 환경 변화에 대한 적응이 가능하다는 것을 제안한다.

• 한국수산과학회지
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• 제2권2호
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• pp.161-172
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• 1969

Ten experimental tuna long line fishing operations were performed with the long lines A and B, in combination casting orders of BA and AB. The long line B differs from A in its additional main line length per basket and its greater depth of submersion (Table 1). The BA casting order results in an AB hauling order, so that the long line B is casted at an earlier time of a day and fishes for a longer period than A line (fig. 2). The number of fish caught was divided into subclasses in order to be subjected to $x^2-tests$ (Table 2). The first series of $x^2-tests$ were calculated using the hooking rates of two subclasses with other factors pooled (Table 3). The second series of $x^2-tests$ were calculated to obtain the interactions between two subclasses when other factors differed (Table 4). Attention was paid to the extremely small interactions as well as to the large interactions in order to find out whether a factor functions in the same way or in a contradictory way when the other factors involved differ. The test result is summarized in Table 5. The relationship between the hook casting time (relative to the sunrise time) and the hooking rates reveals the feeding behavior of particular species (fig. 3) A high hooking rate for yellowfin tuna shown in the period from one hour before sunrise to the moment of sunrise suggests that they feed actively in that period. Their poor hooking rate on earlier casted hooks suggests that they do not feed well under conditions of darkness and that they feed best while the hooks are sinking. Furthermore it is likely that yellowfin tuna maintain a shallow depth in the daytime, for the $x^2$ interaction between the line casting order BA and AB shows their persistant preferance of the long line A regardless of line casting order. Bigeye tuna show their feeding behavior under conditions of darkness, and show a preference for the sea's deeper layer. Alepisaurus borealis (Gill) show their feeding behavior under conditions of darkness more significantly than the bigeye tuna and their preferance for deep layers is also more significant. Marlins (mainly Makaria mazara) show a feeding behavior which is similar to the yellowfin tuna. The author emphasizes that certain variations of the hooking rates in relation to the line easting time were caused by an inadequate fishing depth as well as by the fish preference for a particular feeding time. When the part of the line casted in pre-dawn hours and hauled in the pre-sunset hours show a significantly lower hooking rate than other parts of the line, then it is concluded that tile hooks settled in a sea layer too deep for feeding.

• 수산해양기술연구
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• 제42권4호
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• pp.234-239
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• 2006

This paper introduces an auto-feeding system to exactly control the feeding time and the amount to cultured fishes in aquaculture industrial field. To reduce expensive costs or labors in this field, it was designed by the concept of controlling feed quantity exactly on the basis of fish's feeding behavior pattern in water tank. A feed control method of this system was developed for controlling feed amount by rotor capacity and motor rotated number. Moreover, a scattering section was selected by rotate way of propeller wing to scatter dried feed to designated site, and then, the diameter of its wing was 250mm and maximum scattering distance was 7.6m for 600rpm. Furthermore, the scattering ways were embodied 2 types such as a simplified way and a multistage shift way looks like a manual scattering. As a results, the multistage shift way is more effective to discharge the dried feed widely than the simple way in the water tank.

• Asian-Australasian Journal of Animal Sciences
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• 제17권5호
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• pp.655-658
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• 2004

Heat stress is known to affect physiological systems in goats. This study investigated changes in nutrient digestibility, behavior and growth hormone secretion among goats in a hot environment (H; 35${\pm}$ 1.2$^{\circ}C$, [RH] 80${\pm}$7.2%, 13 d), and in a thermoneutral environment (T; 20${\pm}$0.6$^{\circ}C$, [RH] 80${\pm}$3.4%, 20 d), and accompanied by the same restricted diet as provided in the hot environment. The following results were obtained: rectal temperature and water intake were higher in the H treatment than in the T treatment or TR treatment, while hay consumption was lower. CP, NDF and ADF digestibility was highest in H treatment. Time spent eating in the H treatment was also the highest, followed in order by T treatment and TR treatment. Ruminating time was lower in H treatment than in T treatment or TR treatment, and reposing time was highest in the TR treatment. Growth hormone concentrations in T increased 4.5 h after feeding. In H, growth hormone concentrations increased 0.5 h after feeding. However, growth hormone concentrations were not changed following TR feeding. In conclusion, heat exposure in goats decreased feed intake, but increased digestibility. However, when goats in a thermoneutral environment received the same restricted feeding as they received in the hot environment, digestibility increased. Between the H treatment and TR treatment, the changes in digestibility were accomplished by coordinate changes in hormone secretion in order to maintain body homeostasis. To maintain energy balance under a hot temperature or a restricted feeding condition, goats may control their metabolism by changing growth hormone release.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2002년도 춘계학술대회 논문집
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• pp.78-81
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• 2002

To achieve high precision machine totals with high speed, it is needed to develop excellent rigidity statically, dynamically and thermally as well. In this view the chief things that thermal deformation of machine tool structure is directly related to high precision. And thermal behavior for transmission procedure have an effect on high precision. It is needed to exact temperature distribution of each members and all contact elements included for machine tool structure. This paper deals with thermal behavior caused by temperature variation in a high speed feeding process. At this procedure of temperature distribution is estimated using a Predictor-Corrector Method.

• Child Health Nursing Research
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• 제26권2호
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• pp.277-285
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• 2020

Purpose: This study aimed to identify factors-both infant-related and maternal-associated with pressure to eat as a feeding practice among mothers with infants. Methods: This study used a cross-sectional design and included 163 mothers of infants aged 2~12 months. Of the 180 self-reported questionnaires that were distributed, 163 (91%) were included in the data analysis. Multiple regression analysis was used to identify the factors associated with pressure to eat as a feeding practice among the mothers. Results: Infant's temperament (β=-.17, p=.035), mother's body mass index (β=-.16, p=.048), and concern about the infant being underweight (β=.30, p=.001) were associated with pressure to eat as a feeding practice among mothers. The explanatory power of these variables in the predictive model was 19.2%. Conclusion: Educational programs should be developed for improving mother's awareness of cues from infants with difficult temperament. In addition, educational interventions regarding the correct evaluation of infant's weight are needed to relieve mother's concern about their infant's being underweight. These interventions might be helpful to reduce the prevalence of pressure to eat as a feeding practice among mothers with infants.