• 한국유체기계학회 논문집
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• 제18권6호
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• pp.19-26
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• 2015

The present paper presented and applied an exergy analysis method to evaluate the magnitudes and the locations of exergy losses in the conventional desuperheating and depressurizing process of high pressure and temperature steam delivery system. In addition, for the reduction of exergy losses occurred in conventional process, the present study proposed new alternative processes in which the pressure reducing valve and the desuperheater of conventional process are substituted with steam turbine and heat exchanger, and their effects on exergy loss reduction and exergy efficiency improvement are theoretically investigated and compared. From the present analysis results, the total exergy loss caused in conventional desuperheating and depressurizing process accounted for 66.5% of exergy input and 85% of the total exergy loss was due to the mixing between steam and cold water(e.g desuperheating). However, it was shown from the present analysis results that the present alternative processes can additionally reduce exergy loss by maximum 92.7% of the total exergy loss in conventional process, and can also produce additional and useful energy, the electricity of 220.6 kWh and the heat of 54.3 MJ/hr.

• 신재생에너지
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• 제18권3호
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• pp.1-9
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• 2022

This study analyzed the anticipated supply-and-demand of forest biomass energy (through wood pellets) until 2050, in South Korea. Comparing the utilization rates of forest resources of five countries (United Kingdom, Germany, Finland, Japan, and S. Korea), it was found that S. Korea does not nearly utilize its forest resources for energy purposes. The total demand for wood pellets in S. Korea (based on a power generation efficiency of 38%) was predicted to be 3,629 and 4,371 thousand tons in 2034 and 2050, respectively. The anticipated total wood pellet power generation ratio to target power consumption is 1.13% (5,745 GWh), 1.17% (6,336 GWh), and 1.25% (7,631 GWh) in 2020, 2030, and 2050, respectively. Low value-added forest residues left unattended in forests are called "Unused Forest Biomass" in S. Korea. From the analysis, the total annual potential amount of raw material, sustainably collectible amount, and available amount of wood pellet in 2050 were estimated to be 6,877, 4,814, and 3,370 thousand tons, respectively. The rate of contribution to Nationally Determined Contributions was up to 0.64%. Through this study, the authors found that forest biomass energy will contribute to a carbon neutral society in the near future at the national level.

• Asian-Australasian Journal of Animal Sciences
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• 제6권2호
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• pp.235-242
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• 1993

In order to investigate the effects of dietary cellulose and protein levels on chick performance, four semi-purified diets were formulated so as to contain cellulose at levels of 5% (LC) and 20% (HC) in combination with 10% (LP) and 20% (HP) protein, and fed ad libitum to 1-week-old White Leghorn male chicks for 3 weeks. There were no significant differences in feed intake, body weight gain and feed efficiency between the LC-HP and HC-HP groups. All parameters were lower in the LP groups; the HC-LP group consumed very small amount of feed and lost body weight during the experiment. The retention rates of DM, ash, nitrogen and energy were higher in the HP than the LP groups. The triglyceride concentration of carcass was lower in the HC-LP group and that of liver was higher in the LC-LP group. The carcass total cholesterol level was higher in the HC-HP group. The relative weight of most digestive organs was higher in the HP group irrespective of the cellulose level. In conclusion, the chick performance was primarily influenced by dietary protein level, and when the chicks were fed inadequate levels of protein, the low cellulose level gave a better performance than the high cellulose level.

• 태양에너지
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• 제18권2호
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• pp.19-29
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• 1998

국내 소비 에너지 사용량의 약 97%를 수입에 의존하고 있고, 지구온난화와 관련된 환경문제가 심각하게 대두되고 있는 실정이다. 또한 우리나라 에너지 부문별 소비형태에서 47%를 차지하는 산업용의 에너지 소비는 대부분 유류애 의존하고 있고, 그 중에서도 제조부분의 소비가 91.5%로 나타나고 있어, 이 부분에 대체어네지원의 개발, 대체 시스템의 적용이 절실히 요구되고 있다. 우리 나라에서도 국가적 에너지 절약과 쾌적한 주거환경 및 생활의 편리함을 위해 기존 화석에너지로부터 무공해 청정에너지(Clean Energy)로 그 사용형태가 바뀌어 가는 지금 그 양과 질적인 면에서 무한정이고 무공해인 대체 에너지원으로서의 태양에너지는 다양한 이용분야가 개발되어 실용화되고 있다. 국�K의 경우 대표적으로 평판형 태양열집열기를 이용한 온수급탕 시스템을 들 수 있고, 냉난방, 산업공정열 및 태양열 발전 분야에 대한 실용화 및 타당성 연구가 활발히 진행되고 있다. 따라서 본 고에서는 태양열 시스템의 중요한 구성요소인 고효율 집열기술에서 산업용 응용($70{\sim}150^{\circ}C$)에 적합한 것으로 기대되는 진공유리관형 태양열집열기, 국내 외 기술개발 동향과 산업공정열의 대체 가능성에 대하여 기술하였다.

• Asian-Australasian Journal of Animal Sciences
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• 제10권5호
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• pp.445-454
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• 1997

Rice bran commonly available in Bangladesh is a mixture of rice hulls (60%), bran (35%) and polishing (5%), referred here as rice mill feed (RMF). Dose response effect of RMF supplementation to a straw diet including a zero level was measured on the intake, digestibility, nitrogen balance, microbial N yield and growth rate of growing native (Bos indicus) bulls. Twelve bulls of 33 months old and $272{\pm}31.5kg$ weight were randomly allocated to diets having 0 (T1), 1 (T2) and 2 (T3) kg RMF in addition to 200 g wheat bran, 200 g molasses, 60 g salt and 30 g oyestershe\l powder. Concentrate intake was 5.5, 19.2 and 29.5% of the dietary intake for the T1, T2 and T3 treatment respectively. RMF supplementation had no significant effect on the straw DM intake. However, with the increasing levels of RMF supplementation, total DM & digestible OM intake and the whole gut digestibilities of DM, OM, N & ADF increased but in deminishig return. Total microbial N yield estimated from the urinary purine excretion were 15.35, 26.56 and 38.44 g/d for the treatment T1, T2 and T3 respectively. Both the N intake and the N balance increased linearly in response to increasing level of RMF. Supplementation of RMF linearly increased the energy intake and dietary energy concentration. Growth rate in the T1, T2 and T3 treatments were 112, 125 and 250 g/d respctively. The basal N excretion and the maintenance energy requirement of the experimental animals were estimated to be 615 mg/kg $W^{0.75}/d$ and 447 kJ/kg $W^{0.75}/d$ respectively. The estimated efficiency on N utilization was 0.83 mg/mg of N intake ($r^2=0.997$) while the efficiency of metabolizable energy utilization for growth was 0.15. Since animal refused higher levels of RMF, inclusion up to 2 kg level (about 25% of the total DM intake) appears to have no depressing effect on the performances of animal. However, RMF itself fail to meet the critical nutrient need of the rumen microbes. Therefore response of supplementing RMF after correcting the critical nutrient deficiency need to be studied.

• Asian-Australasian Journal of Animal Sciences
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• 제19권5호
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• pp.720-726
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• 2006

In an attempt to develop an artificial diet for growing olive flounder (Paralichthys olivaceus), weight gain, feed utilization and nutrient retention were investigated in fish fed moist (MP), semi-moist (SMP) and extruded pellets (EP). Excretion of nitrogen and phosphorus was also estimated based on their whole body gain and intake. EP and MP composed of raw fish and SMP made of formulated powder feed with water were prepared to have the same energy contents on a dry matter basis. A total of 240 fish with an average initial weight of 120 g were randomly distributed to each (20 fish/tank) of 12 circular plastic tanks (4 tanks/treatment) and fed experimental diets for 8 weeks. Fish groups fed EP (209 g) or SMP (209 g) recorded higher final weight than those fed MP (176 g), while dry feed consumption was highest in SMP groups (106 g), followed by MP (71 g) and EP groups (62 g). As a consequence, fish groups fed EP showed much lower feed conversion ratio than the other two groups. Protein efficiency ratio was also significantly higher in fish groups fed EP (2.55) than in those fed MP (1.44) and SMP (1.31). Fish groups fed EP, which showed the highest nitrogen retention of 43.9%, resulted in the lowest excretion of nitrogen of 35.5 g per kg gain. Also, the lowest phosphorus excretion of 6.0 g per kg gain was found in the EP groups with the highest P retention (37.0%) among treatments. Although the EP groups had the lowest dietary energy intake, they retained the highest energy in the whole body among treatments. The present results showed that EP could be more advantageous than MP or SMP in terms of growth, feed utilization and excretion of nitrogen and phosphorus for olive flounder.

• 농업과학연구
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• 제50권3호
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• pp.349-356
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• 2023

Garlic powder (GP) was supplemented in the diet to assess the growth efficiency, nutritional retention, and fecal score of growing pigs. In total, 80 growing pigs ([Yorkshire × Landrace] × Duroc) were arbitrarily allotted (22.04 ± 0.56 kg primary average body weight) to two different trial groups with eight repetitions (three males and two females) in each pen for the 42-day trial. The dietary treatment consisted of control (CON, basal diet), which included 0.2% GP (TRT1). Growing pigs fed the GP diet exhibited an increase (p < 0.05) in body weight on day 42 and a lower (p < 0.05) overall feed conversion ratio compared to the CON pigs; however, the average daily gain and feed intake showed no difference (p > 0.05). Additionally, nutrient utilization of dry matter was greater (p < 0.05) in the GP-supplemented diet group than in the CON group. The feeding methods did not adversely affect the nitrogen and energy utilization and the fecal score significantly (p > 0.05). In summary, growing pigs fed the GP diet showed increased growth and nutritional utilization, and no adverse impact on the fecal score; thus, it could be utilized as a stimulant for improved growth performance.

• Asian-Australasian Journal of Animal Sciences
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• 제16권5호
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• pp.665-671
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• 2003

A factorial experiment was conducted to assess nutrient utilization by growing lambs maintained on three levels each of digestible energy (high: HE, medium: ME, low: LE) and protein (high: HP, medium: MP, low: LP) in nine combinations (HEHP, HEMP, HELP, MEHP, MEMP, MELP, LEHP, LEMP, LELP). The experiment was conducted during the hot season in a semiarid location. Daily dry matter intake (DMI) was similar in all the groups in terms of unit body weight or metabolic body size. Digestibility of DM and nitrogen free extract increased (p<0.01) from low to medium and high energy regimen while the CF digestibility followed a reverse trend. The digestibility of crude protein (CP) decreased from high to medium and low protein regimens while it was similar in terms of energy variation. Nitrogen intake was higher in high followed by medium and low protein regime while fecal and urinary nitrogen loss were similar in all the treatment groups. Lambs in all the three levels of protein were in positive N balance and percent N retention was higher (p<0.01) in high followed by medium and low protein levels whereas it was similar in terms of energy variation. Initial body weight was similar in all the groups while final weight, total gain in the experiment and average daily gain (ADG) were higher in high than medium and low energy regimens. It is concluded that crossbred lambs required 75.1 g DM, 9.6 g CP, 6.3 g DCP and 711 KJ DE/kg W $^{0.75}$or 11.0 g CP/MJ DE or 7.2 g DCP/MJ DE for 93 g average daily gain in a hot semiarid environment.

• Asian-Australasian Journal of Animal Sciences
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• 제30권10호
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• pp.1396-1404
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• 2017

Objective: This study was determined the influence of virginiamycin supplementation on growth-performance and characteristics of digestion of cattle with decreasing dietary net energy value of the diet for maintenance ($NE_m$) from 2.22 to 2.10 Mcal/kg. Methods: Eighty crossbred beef steers ($298.2{\pm}6.3kg$) were used in a 152-d performance evaluation consisting of a 28-d adaptation period followed by a 124-d growing-finishing period. During the 124-d period steers were fed either a lesser energy dense (LED, $2.10Mcal/kg\;NE_m$) or higher energy dense (HED, $2.22Mcal/kg\;NE_m$) diet. Diets were fed with or without 28 mg/kg (dry matter [DM] basis) virginiamycin in a $2{\times}2$ factorial arrangement. Four Holstein steers ($170.4{\pm}5.6kg$) with cannulas in the rumen (3.8 cm internal diameter) and proximal duodenum were used in $4{\times}4$ Latin square experiment to study treatment effects on characteristics of digestion. Results: Neither diet energy density nor virginiamycin affected average daily gain (p>0.10). As expected, dry matter intake and gain efficiency were greater (p<0.01) for LED- than for HED-fed steers. Virginiamycin did not affect estimated net energy value of the LED diet. Virginiamycin increased estimated NE of the HED diet. During daylight hours when the temperature humidity index averaged $81.3{\pm}2.7$, virginiamycin decreased (p<0.05) ruminal temperature. Virginiamycin did not influence (p>0.10) ruminal or total tract digestion. Ruminal (p = 0.02) and total tract digestion (p<0.01) of organic matter, and digestible energy (p<0.01) were greater for HED vs LED. Ruminal microbial efficiency was lower (p<0.01) for HED vs LED diets. Conclusion: The positive effect of virginiamycin on growth performance of cattle is due to increased efficiency of energy utilization, as effects of virginiamycin on characteristics of digestion were not appreciable. Under conditions of high ambient temperature virginiamycin may reduce body temperature.

• 농업과학연구
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• 제49권3호
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• pp.441-450
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• 2022

This study explored the effects of milk flavor (MF) supplementation on growth efficiency, nutrient absorption, fecal score, and blood profiles in weaning piglets. A total of 80 (21 days old) crossbred ([Yorkshire × Duroc] × Landrace) healthy weaned piglets with an initial body weight (BW) of 7.05 ± 1.22 kg were randomly allotted to one of two nutritive treatments with 8 repetitions and five pigs (2 female and 3 male) per pen. The experiment was divided into 2 phases (d 0 - 21, and d 21 - 42), and the dietary treatments consisted of TRT1, basal diet, TRT2 and basal diet + 1.0 g·kg^-1 MF. At days 21 - 42 and the overall period, the average daily gain (ADG) and average daily feed intake (ADFI) increased (p < 0.05) by receiving the MF added feed. However, MF inclusion did not impact (p > 0.05) the feed efficiency (G : F) throughout the entire experiment. Piglets consuming the MF supplemented diet showed that the apparent total tract digestibility of dry matter (DM), nitrogen (N) and energy (E) did not vary significantly (p > 0.05) between the treatments. All through the experiment, the fecal score and blood profile of the piglets fed the flavor diet also remained unaffected (p > 0.05). In conclusion, MF addition to the diet of the piglets increased their body weight and had no adverse effects on nutrient utilization, fecal score, and blood profile. Thus, MF addition could improve the performance outcomes of weaning piglets.