• 헤리티지:역사와 과학
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• 제43권3호
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• pp.102-121
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• 2010

회암사지에서 출토된 3점의 금탁에 대한 성분조성과 미세조직을 분석하여 조선초기 금탁(琴鐸)을 제작하기 위한 주조방법과 가공처리 기술에 대해 살펴보았다. 분석결과 구리, 주석, 납을 주성분으로 하며, 그 비율은 평균 85 : 8 : 7로 나타났다. 주성분인 구리, 주석, 납을 제외한 10개의 원소가 0.3% 이하의 적은 양으로 검출되어 비교적 잘 정련된 구리소재가 사용되었음을 알 수 있다. 또한 검출된 10개의 미량 원소 중 황과 철은 공급된 구리소재의 원광석으로 황동광이나 휘동광 등 황이 포함된 광석일 가능성을 보여준다. 주조방법으로 사형주조법이 적용되었으며, 방법은 먼저 주물사로 틀을 만들고, 여기에 거푸집을 종 모양대로 세워놓고 구리-주석-납을 용해시킨 청동 주물을 정수리에서 하륜부 방향으로 부어 본체를 만들었다. 형태가 완성된 뒤에는 표면 가공을 위한 추가적인 열처리 없이 가질 작업을 통해 표면을 정리하였다. 모든 가공처리 공정이 마무리된 뒤에는 정수리 부분에 풍판을 연결시키기 위해 철제 연결고리를 끼우고, 그 부분에만 용해된 청동 주물을 부어 고정시켰다. 금탁의 표면에 음각된 명문의 새김법은 축조각과 모조각 기법이 각각 다르게 사용되었고, 획순과 서체에서 차이가 나는 점에 비추어 명문 조각에는 다수의 장인이 동원된 것으로 보인다. 청동기 제작기술의 변천과정을 입증할 만한 사료나 이와 관련된 연구 성과물이 매우 부족한 현 실정에서 제작 연대와 제작 주체가 명확한 금탁에 대한 과학적인 조사연구는 향후 청동기 제작기술 체계의 전반적인 흐름을 이해하는 데 있어서 중요한 자료이다.

• 한국가금학회:학술대회논문집
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• 한국가금학회 2002년도 가을 학술발표논문집
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• pp.116-117
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• 2002

보존온도별(5, 25, 35$^{\circ}C$)로 정액과 희석액의 비율(1：1, 1：2, 1：3)을 달리하여 보존시간(1, 3, 6시간)에 따른 정자운동성을 조사한바, 5$^{\circ}C$ 냉장 온도에서는 희석배율에 따른 보존시간별 정자운동성은 차이가 없었으나, $25^{\circ}C$ 상온에서 6시간, 35$^{\circ}C$ 고온에서 3시간 이상 보존할 때 정액과 희석액의 비율이 1：1보다는 1：2 비율에서 정자운동성이 현저히 높게 유지되었다(P<0.05). 온도가 높을수록 1：1 배율보다는 1：2 이상 희석배율을 높여 주었을 때 정자의 운동성을 높게 유지시킬 수 있었다. Skim milk glucose액을 사용하여 닭 정액을 희석한 후 인공수정 하였을 때, 1회 주입정자수를 0.2, 0.4, 1 및 2억으로 하였을 때 각각 90.67, 94.00, 96.00 및 98.67%의 수정율을 나타냈다. 90%이상의 수정율을 얻기 위해서는 0.2억 이상의 정자 주입이 필요하며, 94%이상 안정적인 수정율을 얻기 위해서는 0.4억의 정자가 필요하다고 판단된다.

• 청정기술
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• 제18권1호
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• pp.69-75
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• 2012

본 연구에서는 휴대용 기기의 터치스크린에 사용된 ITO (Indium Tin Oxide) 투명전극의 재활용에 대한 환경성 평가를 실시하였다. ITO 전극의 경우 도전성과 함께 투명성을 가지는 재료로서 터치 패널이나 LCD (Liquid Crystal Display), ELD (Emitting Light Device), PDP (Plasma Display Panel) 등 각종 디스플레이 장치의 제조를 위한 투명전극으로 수요가 증가하는 추세이다. 특히 인듐과 같은 희소금속을 함유하고 있기 때문에 국가 전략적으로 반드시 재활용되어야 한다. 또한 매립이나 폐기시 발생하는 환경오염 및 인간에게 미치는 영향도 고려해야 한다. 이에 대해 Material Life Cycle Assessment (MLCA)를 이용하여 ITO를 재활용과 매립의 두 가지 처리방법에 따른 환경부하를 정량적으로 분석하고자 한다. 또한 이산화탄소 배출과 투입된 에너지량도 계산하였다. 재활용은 폐 디스플레이에 포함된 ITO의 10, 20, 30%를 회수했을 때를 기준으로 한다.

• Fisheries and Aquatic Sciences
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• 제24권1호
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• pp.19-31
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• 2021

Seaweeds are a potential source of minerals, essential amino acids, fatty acids, proteins, and various bioactive compounds such as antioxidants. The higher water content of seaweeds reduces the shelf life and this requires the appropriate drying method. The drying conditions play a major role in the conservation of nutrient composition in dried seaweeds. In recent years, the seaweed industry has used many different drying methods with advantages and limitations. Hybrid hot-water Goodle dryer (HHGD) which is a special dryer mixed with hot-water and a Korean traditional heating system (Goodlejang) might be a solution to avoid these limitations. The present study evaluated the effect of drying conditions in HHGD on nutrient composition and bioactivities of brown seaweeds. Moreover, freeze-dryer (FD) and HHGD were employed in this study to compare the dried outputs obtained from four brown seaweed species. The present study aims to evaluate the effect of the hybrid hot-water Goodle drying method (HHGDM) on the nutritional composition and antioxidant activity of dried seaweeds. AOAC standard methods were used to analyze the proximate composition of dried samples and their 70% ethanol extract. The intracellular and extracellular antioxidant activities were evaluated using Vero cells and electron spin resonance (ESR) spectrometer respectively. High performance liquid chromatography, apoptotic body formation, and in-vivo experiments were used for further confirmation of the quality of dried output. The proximate composition results obtained from drying in HHGD and FD did not exhibit any significant difference. Moreover, the seaweed extracts from the dried seaweeds by HHGD and FD dryings were also not different and both significantly down-regulated in-vivo and in-vitro oxidative stress. Furthermore, the high performance liquid chromatography results revealed that the two dryers did not make the major peaks different in the chromatograms. Freeze-drying method (FDM) provides elevated quality for dried output, but there are limitations such as high cost and low capacity. The results from a novel HHGD did not provide any significant difference with the results in FD and expressed a potential to avoid the limitations in FD. Overall, these findings solidified the applicability of HHGD over FD.

• Plant Biotechnology Reports
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• 제2권2호
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• pp.123-131
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• 2008

Vitrification methods are convenient for cryopreserving plant specimens, as the specimens are plunged directly into liquid nitrogen (LN) from ambient temperatures. However, tissues and species with poor survival are still not uncommon. The development of vitrification solutions with high survival that cover a range of materials is important. We attempted to develop new vitrification solutions using bromegrass cells and found that VSL, comprising 20% (w/v) glycerol, 30% (w/v) ethylene glycol, 5% (w/v) sucrose, 10% (w/v) DMSO and 10 mM $CaCl_2$, gave the highest survival following cryopreservation, as determined by fluorescein diacetate staining. However, the cryopreserved cells showed little regrowth, for unknown reasons. To check its applicability, VSL was used to cryopreserve gentian axillary buds and the performance was compared with those of conventional vitrification solutions. Excised gentian stem segments with axillary buds (shoot apices) were two-step precultured with sucrose to induce osmotic tolerance prior to cryopreservation. Gentian axillary buds cryopreserved using VSL following the appropriate preculturing approach exhibited 78% survival (determined by the regrowth capacity), which was comparable to PVS2 and PVS1 and far better than PVS3. VSL had a wider optimal incubation time (20-45 min) than PVS2 and was more suitable for cryopreserving gentian buds. The optimal duration of the first step of the preculture was 7-11 days, and preculturing with sucrose and glucose gave a much higher survival than fructose and maltose. VSL was able to vitrify during cooling to LN temperatures, as glass transition and devitrification points were detected in the warming profiles from differential scanning calorimetry. VSL and its derivative, VSL+, seem to have the potential to be good alternatives to PVS2 for the cryopreservation of some materials, as exemplified by gentian buds.

• 공업화학
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• 제17권1호
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• pp.111-117
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• 2006

냉 난방 수요에서 일어나는 환경오염의 최소화와 화석연료 소비를 감소시키기 위해서 에너지보존을 개선시키는 것은 필수적이다. 이러한 점에서 흡수식 열펌프기술은 에너지 절약을 위해서 많은 가능성을 가지고 있다. 흡수식 열펌프는 에너지를 주입하지 않고 폐열의 이용을 높일 수 있는 방법이다. 흡수식 열펌프는 흡수기에서 흡수된 양의 증가가 매우 중요하기 때문에 흡수기 성능이 매우 중요하다. 본 연구에서는 흡수기의 성능을 개선시키기 위해서 메탄올과 글리세린을 작동유체로 하는 두 종류의 흡수기에 관한 연구를 수행하였다. 전자는 흡수기 내에 액상을 접선방향으로 공급하는 것이고 후자는 흡수기 내벽에 나선형 관을 설치하여 액상을 접선방향으로 공급하는 것이다. 실험 결과 후자가 흡수기에서 발생하는 열 및 물질전달이 향상되어 흡수성능이 증가되었음을 알 수 있었다.

• Computers and Concrete
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• 제24권2호
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• pp.151-158
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• 2019

The sustainable development principle of replacing natural resources with renewable material is an important research topic. In this study, waste LCD (liquid crystal display) glass powder was used to replace cement (0%, 10%, 20% and 30%) through a volumetric method using three water-binder ratios (0.47, 0.59, and 0.71) to make cement mortar. The compressive strength was tested at the ages of 7, 28, 56 and 91 days. The test results show that the compressive strength increases with age but decreases as the water-binder ratio increases. The compressive strength slightly decreases with an increase in the replacement of LCD glass powder at a curing age of 7 days. However, at a curing age of 91 days, the compressive strength is slightly greater than that for the control group (glass powder is 0%). When the water-binder ratios are 0.47, 0.59 and 0.71, the compressive strength of the various replacements increases by 1.38-1.61 times, 1.56-1.80 times and 1.45-2.20 times, respectively, during the aging process from day 7 to day 91. Furthermore, a prediction model of the compressive strength of a cement mortar with waste LCD glass powder was deduced in this study. According to the comparison between the prediction analysis values and test results, the MAPE (mean absolute percentage error) values of the compressive strength are between 2.79% and 5.29%, and less than 10%. Thus, the analytical model established in this study has a good forecasting accuracy. Therefore, the proposed model can be used as a reliable tool for assessing the design strength of cement mortar from early age test results.

• Journal of Veterinary Science
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• 제21권5호
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• pp.60.1-60.11
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• 2020

Background: Tumor-associated neoangiogenesis is a crucial target for antitumor therapies. Thalidomide (TAL) is a promising anti-neoangiogenetic drug that has recently been used in the treatment of several malignancies in dogs. Objectives: The aim of the study was to assess the pharmacokinetics of TAL after single oral administration in dogs. Additionally, the influence of feeding on the pharmacokinetic profile of TAL in dogs has been preliminarily investigated. Methods: Six healthy adult female Labradors were enrolled according to a randomized single-dose, 2-treatment, 2-phase, paired 2 × 2 cross-over study design. The dogs were administered a single 400 mg capsule of TAL in fasted and fed conditions. Blood was collected from 15 min to 48 h after dosing, and TAL quantified in plasma by a validated high-performance liquid chromatography method. The pharmacokinetics of TAL were analyzed using a non-compartmental approach. Results: TAL concentration was quantifiable up to 10 h and 24 h after fasted and fed conditions, respectively. C_max (fasted, 1.34 ± 0.12 ㎍/mL; fed, 2.47 ± 0.19 ㎍/mL) and T_max (fasted, 3 h; fed, 10 h) differed substantially between the 2 groups. AUC and t_1/2λz were significantly higher in fed (42.46 ± 6.64 mg × h/L; 17.14 ± 4.68 h) compared to fasted (12.38 ± 1.13 mg × h/L; 6.55 ± 1.25 h) dogs. The relative oral bioavailability of TAL for the fasted group was low (36.92% ± 3.28%). Conclusions: Feeding affects the pharmacokinetics of oral TAL in dogs, showing a delayed, but higher absorption with different rate of elimination. These findings are of importance in clinical veterinary settings, and represent a starting point for further related studies.

• 한국수소및신에너지학회논문집
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• 제33권6호
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• pp.808-818
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• 2022

In this research paper, we investigated the cryogenic line chill down characteristics of liquefied natural gas (LNG). A numerical analysis model was established and verified so that it can calculate the precise cooling characteristics of cryogenic fluid for the stable and safe utilization especially such as LNG and liquid hydrogen. The numerical modeling was programmed by C++ as an one-dimensional homogeneous model. The thermohydraulic cooling process was simulated using mass, momentum, energy conservation equations and appropriate heat transfer correlations. In this process, the relevant heat transfer correlations for nuclear boiling, transition boiling, film boiling, and single-phase heat transfer that can predict the experimental results were implemented. To verify the numerical modeling, several cryogenic line chill down experiments using LNG were conducted at the Korea Institute of Machinery & Materials (KIMM) LNG and Cryogenic Technology Center.

• 한국농공학회지
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• 제22권1호
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• pp.53-66
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• 1980

The research work is concerned with the analytical and experimental studies on the heat transfer phenomenon around the underground concrete digester used for biogas production Systems. A mathematical and computational method was developed to estimate heat losses from underground cylindrical concrete digester used for biogas production systems. To test its feasibility and to evaluate thermal parameters of materials related, the method was applied to six physical model digesters. The cylindrical concrete digester was taken as a physical model, to which the model,atical model of heat balance can be applied. The mathematical model was transformed by means of finite element method and used to analyze temperature distribution with respect to several boundary conditions and design parameters. The design parameters of experimental digesters were selected as; three different sizes 40cm by 80cm, 80cm by 160cm and l00cm by 200cm in diameter and height; two different levels of insulation materials-plain concrete and vermiculite mixing in concrete; and two different types of installation-underground and half-exposed. In order to carry out a particular aim of this study, the liquid within the digester was substituted by water, and its temperature was controlled in five levels-35。 C, 30。 C, 25。 C, 20。C and 15。C; and the ambient air temperature and ground temperature were checked out of the system under natural winter climate conditions. The following results were drawn from the study. 1.The analytical method, by which the estimated values of temperature distribution around a cylindrical digester were obtained, was able to be generally accepted from the comparison of the estimated values with the measured. However, the difference between the estimated and measured temperature had a trend to be considerably increased when the ambient temperature was relatively low. This was mainly related variations of input parameters including the thermal conductivity of soil, applied to the numerical analysis. Consequently, the improvement of these input data for the simulated operation of the numerical analysis is expected as an approach to obtain better refined estimation. 2.The difference between estimated and measured heat losses was shown to have the similar trend to that of temperature distribution discussed above. 3.It was found that a map of isothermal lines drawn from the estimated temperature distribution was very useful for a general observation of the direction and rate of heat transfer within the boundary. From this analysis, it was interpreted that most of heat losses is passed through the triangular section bounded within 45 degrees toward the wall at the bottom edge of the digesten Therefore, any effective insulation should be considered within this region. 4.It was verified by experiment that heat loss per unit volume of liquid was reduced as the size of the digester became larger For instance, at the liquid temperature of 35˚ C, the heat loss per unit volume from the 0. 1m$^3$ digester was 1, 050 Kcal/hr m$^3$, while at for 1. 57m$^3$ digester was 150 Kcal/hr m$^3$. 5.In the light of insulation, the vermiculite concrete was consistently shown to be superior to the plain concrete. At the liquid temperature ranging from 15。 C to 350 C, the reduction of heat loss was ranged from 5% to 25% for the half-exposed digester, while from 10% to 28% for the fully underground digester. 6.In the comparison of heat loss between the half-exposed and underground digesters, the heat loss from the former was fr6m 1,6 to 2, 6 times as much as that from the latter. This leads to the evidence that the underground digester takes advantage of heat conservation during winter.