• 한국약용작물학회지
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• 제24권3호
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• pp.198-206
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• 2016

Background: Electrical conductivity (EC) and pH are important features of nutrient solution, affecting both growth and quality of crops by altering nutrient uptake. Methods and Results: The pH values of nutrient solutions were controlled at 5.0, 5.5, 6.0, 6.5 and EC values were controlled at 0.68, 0.84, 1.23, 1.41 dS/m. Gingesng root weights were higher during the initial growth period when the plants were treated with low pH and low EC nutrient solutions. However, the higher pH and EC levels, the greater the increase in the rate of root weight between the initial and middle growth periods. The highest ginsenoside amount changed during growth period. The total ginsenoside amount was highest in the root, and the lowest in leaves at 45 and 90 days after treatment, respectively, with solution at a pH of 6.0. After 135 days of treatment, the highest total ginsenoside amount was detected in root treated with soluton with EC values of 1.23 dS/m. Conclusions: For the cultivation of ginseng using a nutriculture system, the pH and EC values of nutrient solutions should to be controlled based on the stage of growth and targeted plant organ (root or leaves).

• 설비공학논문집
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• 제11권3호
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• pp.369-376
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• 1999

Experiments were carried out to study the heat transfer characteristics of a disrober for 150 RT LiBr-water absorption heat pump. An experimental apparatus was divided into four sections, a combustion chamber area, two bare-tube areas, and finally a finned-tube area to quantify the heat transfer rate of each section by measuring the generation rate of vapor. Dividing plates was installed at the upper inside part of deserter to prohibit the moving of vapor generated at heating tubes of a section to another section near. In the first bare-tube area, the generation rate of vapor was the largest among the four sections. The finned-tube area only contributed to give sensible heat increase of solution to the saturation temperature. The heat transfer area of the finned-tube area was 52.2%, which absorbed only 9.2% of the total heat from the combustion gas. On the contrary, the heat transfer area of the first bare-tube area was 16.6%, but it absorbed 52.4% of the total absorbed heat. The temperature of the solution at upper part at the finned-tube area was lower than that of the lower part, because weak solution came in upper part of the finned-tube area. But, this tendency was changed at the first and second bare-tube area due to the vigorous heat transfer and fluid flow enhanced by vapor generation through heating tubes. The overall heat transfer coefficient and heat flux were the largest at the first bare-tube area among the other sections.

• 대한기계학회논문집B
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• 제20권1호
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• pp.346-358
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• 1996

A finite volume radiation solution method was applied to a non- orthogonal coordinate system for the analysis of radiative-convective heat transfer about a circular cylinder in crossflow. The crossflow Reynolds number based on the cylinder radius was 20, and the fluid Prandtl number was 0.7. The radiative heat transfer coupled with convection was reasonably predicted by the finite volume radiation solution method. The investigation includes the effects of conduction- to-radiation parameter, optical thickness, scattering albedo and cylinder wall-emissivity on heat transfer about the cylinder. As the conduction- to-radiation parameter decreases, the radiative heat transfer rate increases and conduction rate as well due to the increase in temperature gradient on the cylinder wall which is caused by radiation enhancement. With an increase in the optical thickness, the Nusselt number increases significantly and the temperature gradient shows similar behavior. Though the radiative heat transfer increases with the scattering albedo, the total heat transfer decreases. This is because the decrease in the conduction heat transfer exceeds the increase in the radiation heat transfer. As the wall- emissivity increases, the radiation absorbed in the vicinity of the cylinder wall increases and thereby the total heat transfer increases, even though the conduction heat transfer decreases.

• 태양에너지
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• 제19권4호
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• pp.45-53
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• 1999

본 논문은 태양열을 구동원으로 하고 액체흡수제인 염화리튬(LiCl) 용액을 이용하여 제습/냉방 및 난방을 하나의 시스템으로 이루는 태양열 이용 냉난방 공조시스템 중 여름철 전열교환기의 제습/냉방에 관한 성능실험 결과이다. 여름의 고온다습한 실내공기는 휀에 의해 전열교환기로 유입되어 충진층에서 살수된 LiCl 용액과 직접 접촉하여 제습/냉각된 후, 건조공기로 바뀌어 실내로 취출된다. 한편 수분을 흡수하여 저농도 용액으로 변한 LiCl 용액은 재생기에서 태양열에 의해 다시 고농도 용액으로 바뀌어 흡수포텐셜을 갖는다. 본 실험에서는 형상 및 크기가 다른 3가지 충진재를 사용하여 전열교환기의 제습성능을 비교하였으며, 절대습도기준 총괄 물질전달계수인 $k_xa(kg/m^3h{\Delta}x)$로써 그 성능을 평가하였다. 특히 $k_xa$값은 액체흡수제 유량, 공기 풍량, 충진재 형상 및 충진층 높이에 따라 변한다. 따라서 이에 대한 영향을 조사하기 위하여 여러 가지 실험한 결과, 풍량은 $k_xa$값에 미치는 영향이 컸으나, 유량은 그다지 영향을 미치지 않음을 알 수 있었다. 또한 충진재의 형상에 따른 비교 실험에서 충진재의 직경이 큰 경우에는 충진층 높이의 영향이 컸으나, 직경이 작은 경우에는 높이에 의한 영향이 직경이 큰 경우보다 작았다. 이상의 실험 결과로부터 $k_xa$값을 충진재 형상 및 충진층 높이에 따라 정지하면 최적 전열교환기 설계 및 제작에 기초자료로 활용할 수 있음을 알았다.

• 멤브레인
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• 제4권1호
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• pp.38-45
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• 1994

계면중합법에 의한 막 제조시 여러 제조변수의 영향을 평가하기 위한 실험을 행하여 다음과 같은 결과를 얻었다. 반응물인 MPD(m-phenylene diamine)농도가 증가할수록 배제율은 증가하나 투과유속은 감소하였다. MPD의 경우에 함침시간이 증가할수록 배제율은 증가하나 투과유속은 감소하였다. TMC(trimesoyl chloride)경우에는 함침시간이 증가할 때 투과유속은 감소한 반면 배제율은 증가한 이후 감소하였다. 열처리 온도가 상승함에 따라 투과유속은 증가하나 배제율은 증가한 이후 감소하였다. 첨가제인 NaOH는 중합시 발생하는 염산의 양이 적어 미량이 중화에 필요하였으며, 그 양이 증가할수록 배제율과 누과유속은 증가한 이후 감소하여\ulcorner. 후처리는 ethanol, isoprophlalcohol, $5~7^{\circ}C$의 물로 치환하여 배제율과 투과유속에서 상승을 가져왔으며, $5~7^{\circ}C$ 물의 경우에는 후처리 시간에 따라 극대값을 가짐을 알 수 있었다.

• 한국식품조리과학회지
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• 제12권4호
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• pp.535-540
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• 1996

감자 슬라이스를 CaCl$_2$ 용액과 chitosan 용액에 침지 하거나 혹은 이들 용액의 존재하에서 예열처리 한 후 냉장저장하여 침지 및 예열처리가 감자 슬라이스의 갈변정도, 페놀 함량, PPO 활성의 변화에 대한 영향을 조사한 결과는 다음과 같다. 1. 감자 슬라이스의 L값은 감소하는 경향을 나타내었으나, CaPS는 2주까지 L값이 증가하였고, ChPS는 4주간 L값이 증가하였다(p < 0.05). 또한 예열처리에 의 한 병용 효과에 의해 L값이 가장 증가하였다(p < 0.05). 2. CaPS를 제외한 각 처리군은 total phenol 함량이 감소하였으며(p < 0.05) 예열처 리 한 감자 슬라이스의 total phenol 함량이 더욱 감소하였다(p < 0.05). chloro-genic aicd 함량은 HCaPS를 제외하고 total phenol 함 량의 변화와 같은 경향을 나타내었다. 3. PPO 활성은 침지 및 예열처리를 통하여 감소하였는데 예열처리에 의한 감자 슬라이스의 PPO 활성 이 더욱 감소하였다 이로부터 CaCl$_2$,및 chitosan 용액에 침지 및 예열처리가 갈변억제에 효과적인 것으로 생각되어지며 L값 은 증가하고 페놀함량과 PPO 활성이 감소하였다. 이 러한 효과는 열처리군에서 더 크게 나타났다.

• Journal of Microbiology and Biotechnology
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• 제12권2호
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• pp.268-272
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• 2002

Kinetic experiments on the biological oxidation of $Fe^{2＋}$ by Acidithiobacillus ferrooxidans were conducted by measuring the total organic carbon content. The total organic carbon in the solution was determined with different initial concentrations of $Fe^{2＋}$(4, 9, 15, and 20 mg/ml). The growth of At. ferrooxidans and substrate utilization were described by the Monod expression. The total organic carbon was found to be an indicator of the biomass concentration and thus may be effectively utilized for estimating cell growth rates in kinetic model development.

• 한국세라믹학회지
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• 제46권6호
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• pp.596-601
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• 2009

Double-layered ZnO nanostructures have been synthesized by aqueous solution method on (001) plane of ZnO nanorod. A stepwise changing of aqueous solution concentration gave rise to a new nano-structured layer consisting of either multiple of nanorods or nanowires with much smaller radii than that of the ZnO nanorod on which the new layer was grown. As the first step the ZnO nanorods have been grown to have the (001) preferential orientation in the aqueous solution consisting of 0.1M zinc nitrate and 0.1 M HMT. This preferentially aligned ZnO nanorods have been regrown in either a less diluted solution of 0.01M zinc nitrate and 0.01 M HMT or a more diluted solution of 0.005M zinc nitrate and 0.01 M HMT. A new nano-layer consisting of numerous aligned nanorods or nanowires has been produced on the (001) planes of ZnO nanorods. The growth mechanism for this double layered ZnO nanostructure is ascribed to the (001) polar surface energy instability and inhibition of (001) plane growth due to the step-wise change of aqueous solution concentration; ZnO nuclei formed on the (001) plane grow preferentially in (010) plane instead of (001) plane to reduce the total surface energy. Surface area of ZnO nanostructure can be increased in orders of magnitudes by forming a new layer consisting of smaller nanorods/nanowires on (001) plane of ZnO nanorods.

• 대한한방부인과학회지
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• 제20권1호
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• pp.16-31
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• 2007

Purpose: This study was undertaken to evaluate the effects of the different administration duration of Cynomorii Herba extract solution on the spermatogenic abilities such as concentration, motility and morphological normality of sperm from the testis and the activities of sperm hyaluronidase. Methods : We used the 8-week-old ICR mice and administered 0.3mg/g extract solution of Cynomorii Herba once a day for 30, 60, 90 and 120 days. The control group was administered the normal saline in the same way and duration. We examined the number of total, motile and normal sperm from the cauda epididymis. And we compared the testicular tissue especially seminiferous tubules between control and treated groups by histochemical methods. At the end we observed the difference of sperm hyaluronidase activities between control and treated groups. Results : The significant differences were observed in the concentration of total sperm, the motility and normality of spermatozoa of the Cynomorii Herba extract solution administered groups compared to the control group in 60 and 90 days groups. In the histological analysis of the testicular tissues, the enlargement of testicular lobe diameter and apparent vasculogenesis between testicular lobes were observed in the Cynomorii Herba extract solution administered groups compared to the control group, respectively. Also, the activity of hyaluronidase was significantly increased in the Cynomorii Herba extract solution administered groups compared to the control group. Conclusion : This study shows that Cynomorii Herba has the beneficial effect on the concentration, morphology and motility of sperm especially in 60 and 90 days administration group. We can suggest that Cynomorii Herba extract solution be useful for the treatment of male sexual dysfunctions and infertility.

• 한국식품영양과학회지
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• 제38권5호
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• pp.587-593
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• 2009

당액에 수삼을 넣고 졸이는 횟수에 따라 얻어진 인삼정과 및 정과액의 품질특성을 조사하여 인삼정과의 품질향상을 위한 기초자료를 얻고자 하였다. 인삼정과는 수삼 8 kg을 2배량의 물 16 kg을 넣어 5분간 삶은 후 삶은 물 8 kg을 제거하고 설탕 10 kg을 넣어서 60분간 졸여서 24시간 당침하는 작업을 5회에 걸쳐 행하였다. 졸임 횟수가 증가함에 따라 정과와 정과액 모두 수분함량과 pH는 낮아졌고 정과액의 $^{\circ}Brix$는 상대적으로 높아졌다. 정과 내 조사포닌 함량은 원료삼의 4배가 증가하였으며 구성사포닌 중 Rf와 Rd의 함량이 많이 증가하여 각각 원료삼의 77배 및 16배가 높아졌으며 기타 검량된 구성사포닌은 감소하였다. 정과액에서도 정과에서와 같은 경향으로 인삼의 사포닌이 용출되어 마지막 정과액(GJS 5)에서 Rf와 Rd 및 조사포닌 함량이 각각 15.05, 3.54 및 61.88 mg/g이었다. 또한 졸임 과정 동안 수분증발에 의하여 정과 및 정과액 모두 총 당 함량은 증가하였으며 졸이는 동안 glucose와 fructose의 함량도 증가하였다. 정과의 유기산 함량은 당을 첨가하여 졸이기 시작하면서 급격하게 감소하였으며, 정과액은 졸임 횟수가 증가할수록 malic acid와 citric acid가 증가하는 경향이었다. 정과 및 정과액의 색도는 졸임 횟수가 증가할수록 L값은 낮아지고 a값과 b값은 증가하는 경향이었다.