• Korean Chemical Engineering Research
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• 제60권4호
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• pp.525-534
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• 2022

본 연구에서는 물과 전기의 동시 생산이 가능한 pressure retarded membrane distillation (PRMD)의 폐루프식 구성 디자인을 기수담수화에 적용해 최적 운전 조건과 성능 평가를 수행하였다. 시뮬레이션 결과 80 ℃ 이상의 폐열이 공급될 때 순 에너지 생산량이 양수 값을 보이며 90 ℃ 이상일 때 안정적인 전력 생산이 가능한 것을 확인할 수 있었고 최적 유입수 유량은 0.6 kg/s를 나타냈다. 이 조건에서 3 g/L의 기수가 유입될 때 순 에너지 생산량은 2.56 W/m², 물 플럭스는 8.04 kg/m²/hr의 값을 나타냈다. 기수의 농도가 1-3 g/L로 변화할 때 물 플럭스나 에너지 생산량은 큰 변화가 나타나지 않았고, 해수가 유입수로 사용될 때와 비교하면 더 높은 물 플럭스와 순 에너지 생산량을 보였다. 이를 통해 에너지 생산이라는 측면에 집중한다면 기수를 사용해서 PRMD를 운전하는 것이 더 효율적이라는 것을 확인할 수 있었다.

• 한국수산과학회지
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• 제50권3호
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• pp.257-262
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• 2017

This study was conducted to investigate the growth and skin color of red- and white-colored fancy carp Cyprinus carpio var. koi juvenile reared at different water temperatures (21, 24, 27, and $30^{\circ}C$) for eight weeks. Two experimental diets were prepared to contain 10% Arthrospira platensis or 10% Arthrospira pacifica powder. After the feeding trial, survival was 100% in all group. Weight gain of fish reared at 24, 27, and $30^{\circ}C$ was higher than $21^{\circ}C$ group. Feed efficiency was not affected by water temperature and dietary Arthrospira sp. Daily feed intake tended to increase with water temperature. The $a^*$ value of skin coloration was affected by Arthrospira sp., but not by water temperature. Fish fed the diet containing A. pacifica powder reared at $27^{\circ}C$ had the highest $a^*$ value among the groups. Total carotenoids were highest in fish fed the diet containing A. pacifica powder reared at $21^{\circ}C$. Based on the results of this study, we conclude that 24-$30^{\circ}C$ water temperature was the optimal range for growth, and dietary inclusion of A. pacifica improved the skin redness of red- and white-colored fancy carp reared at $27^{\circ}C$.

• Asian-Australasian Journal of Animal Sciences
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• 제11권6호
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• pp.746-750
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• 1998

This experiment was conducted to investigate the water requirement of exercising sheep. Nine Merino ewes were allocated into three groups differing in water supply after exercise, group 1(G1) supplied water ad libitum, group 2 (G2) supplied with water twice a day, and group 3 (G3) supplied with water once a day. The ewes were exercised outdoors using a circular exercising machine at a speed of 5 km/h for 1 hour for 12 consecutive days. Total daily water intake (TDWI) of animals in G3 was significantly lower (p < 0.05) than that of those in G1 and G2. TDWI of the 2 later groups was not different. TDWI of G3 was about 60% of that of G1. Feed intake of G3 was significantly (p < 0.05) lower than that of the other two groups. Immediately after exercise, rectal temperature (RT) of animals in G1 was significantly (p < 0.05) lower than those in the other groups. Respiration rate (RR) of animals in all three groups was not significantly different. Faecal moisture of animals in G3 was significantly lower (p < 0.05) than those in the other groups. The results indicate that for optimum productivity sheep should be given water at least twice a day.

• 멤브레인
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• 제1권1호
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• pp.34-43
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• 1991

물에 대해 수착선택성이 높은 아세트산 셀룰로오스 치밀막(CA막)과 에탄올에 대해 수착선택성이 높은 실리콘 고무막(SR막)을 통한 물(1)/에탄올(2) 이성분 혼합액의 투과증발에 있어서 막의 친화성과 최적 조업조건의 관계를 조사하였다. CA막과 SR막을 제조하여, 이들 막에서의 수착량, 수착선택도, 투과증발 분리도 및 투과증발 속도를 실험으로 구하고 서로 비교하였다. 하류압력의 영향을 Thompson다이아그램을 써서 분석하였고, 공급액 농도와 조업 온도 변화에 따른 수착 및 투과증발 특성을 활동도 계수, 가소화 효과, 활성화에너지 등으로 설명할 수 있었다. CA막을 사용한 물의 분리의 경우에는 물에 대한 투과증발 분리도 ($[\alpha^2_1]_{PV}$) 및 투과증발 속도 모두 하류압력이 낮고, 공급액의 농도가 중간 정도이고, 온도가 높은 조업조건이 유리하였다. 그러나 SR막을 사용한 에탄올의 분리의 경우에는 에탄올에 대한 투과증발 분리도 ($[\alpha^2_1]_{PV}$) 는 하류압력이 높을수록, 공급액 중의 에탄올 농도가 낮을수록, 조업온도가 낮을수록 증가하였지만, 투과증발 속도는 반대의 경향을 나타내었다.

• Journal of Mechanical Science and Technology
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• 제17권6호
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• pp.896-905
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• 2003

A linear motor has many advantages next to conventional feed mechanisms: high transitional speed and acceleration, high control performance, and good positioning accuracy at high speed. Through the omission of a power transfer element, the linear motor shows no wear and no backlash, has a long lifetime, and is easy to assemble. A disadvantage of the linear motor is low efficiency and resultant high-temperature rise in itself and neighboring structures during operation. This paper presents the thermal behavior of the linear motor as a feed mechanism in machine tools. To improve the thermal behavior, an insulation layer is used. By placing the insulation layer between the primary part and the machine table, both the temperature difference and the temperature fluctuation in the machine table due to a varying motor load are reduced.

• Korean Membrane Journal
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• 제8권1호
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• pp.31-35
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• 2006

Pervaporation of water/2,2,2-trifluoroethanol (TFEA) mixtures was performed using a NaY zeolite membrane which was prepared by a hydrothermal synthesis. Pervaporation with a zeolite membrane is one of the economic separation technologies for liquid mixtures including organic/water solutions. The effects of a TFEA feed concentration and a temperature were studied on the permeation flux and the separation factor. Not only the water flux increased significantly with the increase of the operating temperature, but also the TFEA flux through the NaY zeolite membrane rapidly increased with the increase of the temperature at the feed concentration below 0.8 mole fraction of TFEA.

• 한국압력기기공학회 논문집
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• 제11권1호
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• pp.39-44
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• 2015

The fracture toughness of 2.25Cr-1Mo cast steel (SA217-WC9) samples which were taken from the check valves of feed water piping of Korean Standard Nuclear Power Plant(KSNPP) was measured by Master Curve method. The measured $T_0$ reference temperature of SA217-WC9 steel was $-30^{\circ}C$. The obtained $T_0$ was compared to the derived value from Charpy impact test data following to SINTEP procedure. The heat-to-heat variation in fracture toughness of SA217-WC9 steel was observed. It was found that the low toughness of a heat of SA217-WC9 steel was attributed to the coarse MnS inclusion originated by high sulfur content as the results of microanalyses.

• 환경생물
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• 제40권4호
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• pp.651-659
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• 2022

본 연구는 연어(Oncorhynchus keta) 치어의 성장, 생존 및 혈액 성상에 미치는 사육수온(8, 11, 14 및 17℃)의 영향을 연구하기 위해 수행되었다. 실험 종료 시 연어의 체중(body weight, BW)은 14℃ 실험구에서 가장 높았을 뿐 아니라, 특이성장률(specific growth rate, SGR), 사료전환 효율(feed conversion ratio, FCR), 사료효율(feed efficiency, FE), 증중률(weight gain, WG) 및 비만도(condition factor, CF)와 같은 성장지표에서도 14℃ 실험구가 가장 높은 경향을 나타내었다. 생존율(survival rate)은 8℃와 11℃ 실험구에서 100%를 보였고, 14℃ 실험구에서는 96% 및 17℃ 실험구에서는 98%를 각각 나타내었다. 혈장 성분 중 알라닌 아미노전이효소(alanine aminotransferase, ALT)는 17℃ 실험구에서 유의한 감소를 보였으나, 알부민(albumin), 총단백질(total protein, TP), 나트륨(sodium, Na⁺), 칼륨(potassium, K⁺) 및 염소(chloride, Cl^-)는 유의한 변화를 보이지 않았다. 실험 종료 시 연어의 체성분 조사를 실시한 결과, 수분(moisture), 단백질(crude protein) 및 회분량(crude ash)은 수온에 따른 유의한 변화는 보이지 않았으나, 지질(crude lipid)은 다른 실험구에 비해 8℃ 실험구에서 유의하게 높은 경향을 보였다. 결론적으로 연어 치어가 성장하는데 필요한 최적의 사육 수온은 14℃로 보이나, 혈액 성상 등 생리적인 영향은 향후 추가적인 연구가 필요한 것으로 판단된다.

• 한국수산과학회지
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• 제47권6호
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• pp.847-852
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• 2014

The aim of this study was to investigate the effects of stocking density and water temperature in the rearing of the longtooth grouper Epinephelus bruneus. Juvenile fish [mean body weight (BW)=$6.9{\pm}1.1g$] were raised for 6 weeks, in four density groups of 0.25, 0.5, 0.75, and 1 individuals/L. There were no significant differences in weight gain (WG) or specific growth rate (SGR) among the density groups; however, both WG and SGR tended to be higher in the low density group. After 6 weeks of rearing in temperature-controlled water ($23.6{\pm}0.8^{\circ}C$) and ambient temperature water ($19.6{\pm}1.8^{\circ}C$), there were no significant differences in WG or SGR values, but both tended to be higher in the temperature controlled water. The feed efficiency (FE) and daily feed intake (DFI) and WG values were also higher in the temperature-controlled water than in the ambient temperature water. WG values were lower at lower water temperatures. The same pattern was observed for SGR, FE, and FI, all of which exhibited lower values at lower temperatures. In particular, WG, SGR, and FE values all tended to decrease at the $16^{\circ}C$ water temperature. The effects of water temperature on 1-year fish (mean BW = $387.6{\pm}30.2g$) and 3-year fish (mean BW = $1,338.3{\pm}73.8g$) were similar to those of the juvenile fish (0-year fish).

• 한국수산과학회지
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• 제42권3호
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• pp.262-267
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• 2009

Two 15-week feeding trials were conducted to investigate feeding rate and feeding frequency for growth of sub-adult flounder in suboptimal water temperature ($12^{\circ}C$). In the first experiment, duplicated groups of fish (initial mean weight of 279 g) were fed a extruded pellet once a day at the different feeding rates of 0.1, 0.15, 0.2, 0.3% body weight per day (BW/d), and satiation (0.32% BW/d). Weight gain and feed efficiency were increased significantly (P<0.05) with increase in feeding rates from 0.1 to 0.3% BW/d, but there were no significant differences in weight gain and feed efficiency of fish fed the diet between 0.3% BW/d and to satiation. Crude protein content of dorsal muscle of fish fed the 0.1% BW/d diet was significantly (P<0.05) lower than that of the other groups. In the second experiment, duplicated groups of fish (initial mean weight of 281 g) were fed to apparent satiation with a extruded pellet at three different feeding frequencies (one meal every two days, one meal a day and two meals a day). Weight gain, feed efficiency and condition factor of fish fed one meal every two days were significantly (P<0.05) lower than those of fish fed one meal and two meals a day, but there were no significant differences in weight gain, feed efficiency and condition factor of fish fed between one meal and two meals a day. Based on the results of this study, optimum feeding frequency is one meal a day with satiation feeding for growth and feed efficiency of sub-adult flounder (270-350 g) in suboptimal water temperature ($12^{\circ}C$).