• 한국생물공학회:학술대회논문집
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• 한국생물공학회 2002년도 생물공학의 동향 (X)
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• pp.201-204
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• 2002

gellan 생산의 최적 pH 조건을 알아보기 위해 삼각플라스크와 회분식 발효를 이용 하여 실험하였다. 삼각플라스크 내에서 초기 pH 7.0 은 1.66g/ ${\ell}$ 의 gellan 을 생산하였고 , 회분식 발효에서는 pH 5.5-8.5 의 범위에서 pH를 조절하면서 실험한 결과, pH 3.0 에서 균체량 O.48g/ ${\ell}$f) 및 gellan 생산량O.97g/ ${\ell}$) 이 최대값을 나타내었다.

• 한국물환경학회지
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• 제20권1호
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• pp.86-92
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• 2004

Lab-scale experiments have been carried out to investigate ammonia stripping with a modified spray tower for removing ammonia nitrogen from swine wastewater. The operating conditions such as initial pH, temperature, air flow, hole size of distributor determining the diameter of water drops, and influent solids concentration were closely examined focusing on removal efficiency of ammonia. As a result of the experiment, in order to achieve high rate of ammonia removal by the air stripping system, the air flow rate must be supplied at high rate with sufficiently high initial pH, temperature. The optimum operating condition to meet the residual ammonia concentration of 300 mg/L was the initial pH of 11.0 at $35^{\circ}C$ with the air flow rate of 20 L/min. It also showed that the smaller hole size is, the higher removal rate of ammonia is expected. However, when used a small sized distributor (2 mm), the flooding problem at the upper column occurred due to clogging of the hole. With regard to the influent solids concentration, it was showed that the lower concentration of solids, the higher removal rate of ammonia. The removal of particulate materials in influent led to improve the removal efficiency of ammonia, rather than to control the operating condition including initial pH, temperature, and air flow. The empirical correlation between KLa and operating parameters would be driven as, $K_{La}=(0.0003T-0.0047){\cdot}G^{0.3926}{\cdot}L^{-0.5169}{\cdot}C^{-0. 1849}$. The calculated $K_{La}$ from proposed formula can be used effectively to estimate the optimum reaction time and to calculate the volume of modified spray tower system.

• 한국식품저장유통학회지
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• 제9권1호
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• pp.51-55
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• 2002

느타리버섯을 이용하여 김치를 제조한 후 숙성 중 식품학적 특성을 조사하였다. 느타리버섯 김치의 숙성기간에 따른 pH를 측정한 결과 생 느타리버섯 김치는 처음에 대조구인 배추김치보다 높았으나, 숙성기간이 지남에 따라 그 값이 배추김치에 비하여 낮게 나타났으며, 데친 느타리버섯 김치는 배추김치보다 조금 높게 나타났고, 적정산도는 pH의 경우와 반대현상으로 나타났다. 아미노태 질소 함량은 숙성기간이 지남에 따라 증가하는 경향이었는데, 생 느타리버섯 김치는 배추김치에 비하여 그 함량이 높게 나타났으며, 데친 느타리버섯 김치는 배추김치와 비슷하게 나타났다. 김치의 환원당은 숙성기간이 지남에 따라 크게 감소하였는데, 생느타리 버섯 김치의 함량은 배추김치보다 높게 나타났고, 데친 느타리버섯 김치는 조금 낮게 나타났다. 배추김치의 생균수는 숙성 2일째는 급격하게 증가하였으며, 그 이후는 거의 비슷한 수로 나타났다. 느타리버섯 김치도 배추김치와 같은 경향이었는데, 그 수는 배추김치보다 약간 낮게 나타났으며, 젖산균수의 경우는 생균수 거의 같은 경향이었다. 상온에서 1일간 저장한 느타리버섯 김치의 관능검사결과 데친 느타리버섯 김치에 비하여 생느타리버섯 김치가 좋은 값을 나타내었으나, 배추김치에 비하여 기호도가 낮게 나타났다.

• Asian-Australasian Journal of Animal Sciences
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• 제28권9호
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• pp.1296-1302
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• 2015

This study was conducted to examine the effects of supplementing brown seaweed by-products (BSB) in the diet of ruminants on ruminal fermentation characteristics, growth performance, endocrine response, and milk production in Holstein cows. In Experiment 1, the effects of different levels (0%, 2%, and 4% of basal diet as Control, 2% BSB, 4% BSB, respectively) of BSB were evaluated at 3, 6, 9, 12, and 24 h in vitro batch culture rumen fermentation. The pH tended to be higher for the higher level of BSB supplementation, with the pH at 12 h being significantly higher (p<0.05) than that of the control. The concentration of ammonia nitrogen was lower at 3, 9, 12, and 24 h incubation (p<0.05) compared with the control, and tended to be low at other incubation times. Volatile fatty acid concentration appeared to be minimally changed while lower values were observed with 4% BSB treatment at 24 h (p<0.05). In Experiment 2, effects of levels (0%, 2%, and 4%) of BSB on growth performance, endocrine responses and milk production were studied with Holstein dairy cows during transition. Dry matter intake, daily gain and feed efficiency were not affected by BSB supplementation. The concentration of plasma estrogen for the control, 2% BSB and 4% BSB after three months of pregnancy were 55.7, 94.1, and 72.3 pg/mL, respectively (p = 0.08). Although the differences of progesterone levels between BSB treatments and the control were minimal, the concentration in 4% BSB treatment increased to 157.7% compared with the initial level of the study. Triiodothyronine and thyroxine levels were also higher after both three months and eight months of pregnancy than the initial level at the beginning of the study. In addition, BSB treatments during one month after delivery did not affect daily milk yield and composition. In conclusion, the present results indicate that supplementation of BSB did not compromise ruminal fermentation, and animal performance at lower levels and hence may have potential to be used as a safe feed ingredient in dairy cows.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2013년도 제44회 동계 정기학술대회 초록집
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• pp.230-230
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• 2013

In amorphous or microcrystalline thin-film silicon solar cells, p-i-n structure is used instead of p/n junction structure as in wafer-based Si solar cells. Hence, these p-i-n structured solar cells inevitably consist of many interfaces and the cell efficiency critically depends on the effective control of these interfaces. In this study, in-situ plasma treatment process of the interfaces was developed to improve the efficiency of a-Si:H solar cell. The p-i-n cell was deposited using a single-chamber VHF-PECVD system, which was driven by a pulsed-RF generator at 80 MHz. In order to solve the cross-contamination problem of p-i layer, high RF power was applied without supplying SiH4 gas after p-layer deposition, which effectively cleaned B contamination inside chamber wall from p-layer deposition. In addition to the p-i interface control, various interface control techniques such as thin layer of TiO2 deposition to prevent H2 plasma reduction of FTO layer, multiple applications of thin i-layer deposition and H2 plasma treatment, H2 plasma treatment of i-layer prior to n-layer deposition, etc. were developed. In order to reduce the reflection at the air-glass interface, anti-reflective SiO2 coating was also adopted. The initial solar cell efficiency over 11% could be achieved for test cell area of 0.2 $cm^2$.

• 한국미생물·생명공학회지
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• 제30권4호
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• pp.415-419
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• 2002

본 연구는 배추김치 제조시 김치의 단백질원인 젓갈 대신 치즈를 첨가하였을 때 김치의 발효적, 이화학적 및 관능적 품질 특성을 조사하였다. 젓갈이 첨가된 대조구와 치즈가 첨가된 김치 모두 담근 후 2일까지 빠른 속도로 미생물이 증식되었으나, 담근 후 3일부터는 치즈 첨가 김치가 대조군 김치에 비하여 높은 생균수를 보였으며, 치즈 첨가량이 많을수록 더욱 더 높았다 pH는 대조구와 치즈 첨가 김치 모두 담근 후 하루동안 일시적으로 약간 상승하다가 2일째부터 급격히 저하되어 3일째에는 pH4.33-4.18로 가장 맛있다고 일반적으로 평가되는 김치의 pH 범위를 보였으며, 치즈 첨가량이 많을수록 pH가 다소 낮은 경향이었다. 발효속도는 대체로 치즈 첨가량이 많을수록 빨랐으며 특히 발효 3일 이후에는 7% 치즈 첨가군이 발효속도가 가장 빨랐다. 일반성분을 분석한 결과 치즈를 첨가한 시험구에서는 수분이 대조구보다 다소 낮게 나타났고 조단백질과 조지방이 다소 높은 경향을 보였다. 담근 후 3일 된 김치의 관능검사를 실시한 결과 젓갈을 넣은 대조구 김치보다 치즈를 3%, 5% 첨가한 김치가 외관, 향미, 질감, 맛 등 관능에서 대체적으로 좋은 점수를 받았다

• 공업화학
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• 제22권5호
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• pp.562-565
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• 2011

본 연구에서는 합성가스를 기질로 Clostridium ljungdahlii를 생물촉매로 바이오에탄올을 생산하는 공정을 개발하고, pH가 미생물 성장 및 에탄올 생산에 미치는 영향을 분석하였다. 다양한 초기 pH 조건(pH 5~8)에서 pH제어 없이 발효실험을 수행한 결과, 부산물인 acetic acid의 축적에 따라 모든 조건에서 24 h 이내에 pH 4.5 이하로 감소되고 미생물의 성장과 에탄올 생산이 중단되는 것을 확인하였다. 사용된 pH 조건 중에서 가장 높은 초기 pH 8의 경우가 가장 높은 미생물 성장과 에탄올 생산량(0.53 g/L)을 보였으며, 이는 상대적으로 pH의 감소가 늦게 일어나기 때문으로 생각된다. pH를 제어할 수 있는 생물반응기를 사용하여 pH 7로 유지시키며 생물공정을 운전한 결과, 최대 미생물 농도 1.65 g/L과 최대 에탄올 농도 1.43 g/L를 24 h 이내에 얻을 수 있었으며, 이는 pH를 중성영역에서 유지할 경우 C. ljungdahlii의 성장을 최대화할 수 있고, growth-associated production의 특성을 보이는 에탄올의 생산량을 최대화할 수 있는 것을 확인시켜준다.

• 한국자원식물학회지
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• 제11권1호
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• pp.111-117
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• 1998

The effect of chitosan on physicochemical and organoleptic properties of Nabak kimchi was studied during fermentation at 2$0^{\circ}C$ . Viscosity of the juice of Nabak kimchi added with chitosan was lower than that of control group. The viscosity was gradually increased during storage period, especially from 5 days to ,7 days of storage. Initial pH was higher in control group than inchitosan groups. The pH of controlgroup decreased rapidly during 4 days of storage. The pH of chitosan groups was slightly increased during the first 3 days of storage and decreased thereafter. Acidity was rapidly increased from 3 to 5 days. Reducing sugar contents increased up to 3 days and decreased thereafter. Acidity was rapidly increased from 3 to 5 days. Reducing sugar contents increased upto 3 days and decreased therafter. Glutamic acid, alanine, threonine, aspartic acid, proline and valine were the major free amino acids, and as the fermentation preceeded they were increased gradually. There were signigicant differences in saltiness, sourness and aged odor in sensory evaluation of Nabak kimchi solution during fermentation at 2$0^{\circ}C$.

• 한국환경보건학회지
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• 제23권4호
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• pp.97-103
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• 1997

Carbofuran was incubated for four weeks in three differenf types of paddy soil samples at 25$\circ$C. The soil samples prepared in the present study were as follows: control soil, 3% cellulose added soil and 10% cellulose added soil. The degradation rate of carbofuran significantly decreased by the addition of cellulose to soil(p<0.05). The initial pH of soils was 5.0. After incubation for four weeks, the pH of 10% cellulose added soil sample was lower than those of control soil and 3% cellulose added soil. According to increased organic carbon content of the soil, redox potentials of soils decreased. The decreased degradation rate of carbofuran in 10% cellulose added soil was related to the highly negative redox potentials in contrast with the oxidised conditions of control soil and 3% cellulose added soil.

• Asian-Australasian Journal of Animal Sciences
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• 제14권9호
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• pp.1299-1303
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• 2001

For the Exp. 1, a total of fifty four crossbred [(Duroc Yorkshire)${\times}$Landrace] pigs ($77.67{\pm}1.42kg$ average initial BW) were used in a 41-d growth assay to determine the effects of yucca extract supplementation on growth performance, nutrient digestibility and serum characteristics of finishing pigs. Dietary treatments included 1) Control (basal diet), 2) YE60 (basal diet+60 ppm yucca extract), 3) YE120 (basal diet+120 ppm yucca extract). Average daily gain was not improved by yucca extract supplementation during the whole experimental perid (d 0 to 41). Pigs fed control diet showed the best average daily gain. Pigs fed control and YE120 diets tended to increase average daily feed intake compared with pigs fed YE60 diet (quadratic effect, p<0.0001). Gain/feed with control treatment was significantly better than the YE groups (linear effect, p<0.071). However, there was no significant difference among levels of yucca extract (p>0.10). Apparent digestibility of dry matter in pigs fed yucca extract were greater than for pigs fed control diets (linear effect, p<0.017). Pigs fed YE120 tended to have higher digestibility of nitrogen than pigs fed the control diets (linear effect, p<0.019). There were no significant differences in Total-, HDL- and LDL-cholesterol concentrations of serum, and the blood urea nitrogen (BUN) concentrations in serum was not influenced by the yucca extract supplementation (p>0.10). For the Exp. 2, fifteen [(Duroc${\times}$Yorkshire)${\times}$Landrace] pigs ($25.00{\pm}0.50kg$ average initial BW) were used in a 30-d metabolism experiment to determine the effects of yucca extract supplementation on fecal ammonia gas production. Treatments were : 1) Control (basal diet); 2) YE (basal diet+150 ppm yucca extract); 3) BD (basal diet+100 ppm Bio-Dr; yucca extract+far infrared emitted materials). Fecal ammonia gas production differences between d 0 and d 30 were significantly reduced (p<0.05) by feeding BD compared to control and YE. Also, when pigs were fed the diet with YE tended to be decreased ammonia gas production compared to pigs fed the control diet without significant differences (p>0.05). There were no differences for DM and N digestibility among pigs fed the treatment diets. In conclusion, yucca and (or) far infrared radiological materials can be used to make environment-friendly diets for growing-finishing pigs without negative effects on growth performance and nutrient digestibility.