• 한국분말재료학회지
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• 제8권4호
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• pp.231-238
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• 2001

We combined Field-Activated Combustion Synthesis(FACS) with mechanical pressure to produce dense WC-20 vol.%Co composite in one step. The hardness, the fracture toughness and the relative density of the dense WC-20 vol.%Co were investigated. Under the application of 60 MPa pressure and 3000A current on the reactants, the relative density of WC-20 vol.%Co composite was 99.4%. The fracture toughness and hardness were $9.4 MPa.m^{1/2}$ and $1672kg\textrm{mm}^2$ respectively. The fracture toughness and hardness of WC-20 vol.%Co composite produced by FAPACS were lower than that of nanostructured composite, but similar to commercial ones. Therefore we concluded that the FAPACS method which can produce WC-20 vol.%Co within several minutes in one step is superior to conventional ones.

• 생약학회지
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• 제48권2호
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• pp.155-159
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• 2017

Cudrania tricuspidata Bureau (Moraceae) is a traditional oriental medicine that has been widely used as anti-oxidant, anti-inflammatory and immunomodulatory in Korea. This study was performed that the 70% ethanol extract of the roots of C. tricuspidata (CTE) suppressed receptor activator of NF-${\kappa}B$ ligand (RANKL)-induced osteoclastogenesis, actin ring formation in RAW 264.7 cell lines. CTE significantly inhibited the JNK/mitogen-activated protein kinase (MAPK) signaling pathway without affecting ERK and p38 signaling in RANKL-stimulated RAW 264.7 cells. Also, CTE inhibited RANKL-induced expression of c-Fos, an upstream activator of NFATc1. Consequently, CTE suppresses osteoclast differentiation by inhibiting RANKL induced MAPK signaling pathways and disrupts the actin rings in mature osteoclasts. Thus, CTE can be used for the development of osteoporosis treatment drug with a natural material.

• Bulletin of the Korean Chemical Society
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• 제19권12호
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• pp.1320-1325
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• 1998

ZnGa2O4: Mn phosphors were prepared by a new chemical process, and their photoluminescence and electron paramagnetic resonance characteristics were investigated. The chemical method showed a low temperature formation of phosphors and a rod-type shape of particles. The strong ultraviolet emission was observed in the undoped ZnGa2O4 phosphor, while strong green emission in the Mn2+-activated ZnGa2O4 phosphor. The green emission intensity of the phosphor prepared by the chemical method was much stronger than that prepared by the conventional method. This difference with preparation methods was interpreted as due to the difference in the distribution of Mn2+ in the host lattice. From EPR results, it was explained that the line intensity of the undoped ZnGa2O4 is associated with the electrical conductivity of this material and the concentration quenching of green luminescence of ZnGa2O4: Mn at higher Mn2+ concentration is attributed to the coupling by exchange interaction between Mn2+ ions.

• 사상체질의학회지
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• 제13권3호
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• pp.89-101
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• 2001

1. The purpose of study To study the effectiveness of Yangkyuksanhawtang(YST) against Allergic Contact Dermatitis(ACD) I observed the change of cutaneous shape, histochemistry, immunohistochemistry, and the distribution of apoptotic cells. 2. The material and method of study I divided 4-month-old rats into three groups of 10, which are a contrastive group of having applied Acetone olive oil only, ACD group to have intentionally activated Allergic Contact Dermatitis by DNCB and YST group to give medication of Yangkyuksanhawtang extract. And I observed each group of mice after 24, 48 and 72 hours. 3. The result and conclusion of study The change of cutaneous shape and hypersensitive reaction of immunity was significantly decreased by YST in ACD rats. I consider that YST suppressed hypersensitive reaction of immunity and inflammation in ACD.

• Coupled systems mechanics
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• 제12권5호
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• pp.419-428
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• 2023

We have developed a model for estimating the parameters of viscous materials from indirect tensile tests for asphalt. This is a simple Burger nonlinear rheological two-cell model or standard model. At the same time, we begin to develop a more versatile and complex multi-cell model. The simple model is validated using experimental load-displacement results from laboratory tests: The recorded displacements are used as input values and the measured force data are simulated with the model. The optimal model parameters are estimated using the Levenberg-Marquardt method and a very good agreement between the experimental results and the model calculations is shown. However, not all parts of the model are active in the loading phase of the experiment, so we extended the validation of the model to the simulation of the relaxation behaviour. In this stage, the other model parameters are activated and the simulation results are consistent with the literature. At this stage, we have estimated the parameters only for the two-cell uniaxial model, but further work will include results for the multi-cell model.

• Journal of Chest Surgery
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• 제31권9호
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• pp.867-872
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• 1998

배경: 심폐바이패스에 의한 개심술시 적절한 항응고요법은 수술 관련 혈액응고장애를 최소화한다 는 점에서 중요하다. 심폐바이패스시 헤파린 및 프로타민 투여량을 결정하는데에는 활성화응고시간을 이 용한 고정용량법이 용량반응 곡선을 이용한 방법과 함께 보편적으로 사용되고 있다. 대상 및 방법: 저자들은 고정용량법에 대한 전향적 연구를 통해 고정용량 투여후 헤파린 및 프로 타민의 추가 투여 빈도, 헤파린 저항및 헤파린 유발성 혈소판감소증 빈도, 심폐바이패스시 활성화응고시 간 변화 양상, 그리고 아프로티닌 사용시 활성화응고시간 변화등을 분석하였다. 심폐바이패스 시작전 헤 파린 300 unit/kg를 투여하고 5분후 그리고 심폐바이패스 시작후 10분, 30분, 60분(이후 30분 간격)의 활성화응고시간을 측정하여 400초 이하인 경우 100 unit/kg 헤파린을 추가 투여하였다. 프로타민 중화는 사용 헤파린 100 unit당 1 mg을 투여한후 30분에 측정한 활성화응고시간이 130초 이상 또는 130초 미만이 라도 명백한 응고장애가 있을 경우 0.5mg/kg 추가 투여하였다. 결과: 서울대병원에서 개심술을 받은 환자중 80명(성인 50명, 소아 30명)을 대상으로 하였다. 수 술전 활성화응고시간은 성인에서 114.3$\pm$19.3초, 소아에서 119.5$\pm$18.2초로 나이, 체중, 체표면적 및 성 별에 따른 유의한 차이는 발견되지 않았다. 과거 개심술 병력도 수술전 활성화응고시간에 영향이 없었다. 고정용량법 투여후 헤린 추가 투여가 필요하였던 경우는 성인 환자 10례(20%), 소아 환자 3례(10%)였다. 프로타민 추가투여가 필요하였던 경우는 성인에서 9례(18%), 소아에서 10례(33%)였다. 심폐바이패스 시간 과 프로타민 추가 투여 사이에는 상관관계를 찾을수 없었다. 헤파린저항을 보였던 경우는 성인에서만 2명 (4%)이었고 소아는 없었다. 헤파린 유발성 혈소판감소증은 성인에서 2례(4%), 소아에서 1례(3.3%) 관찰되 었다. 심폐바이패스 운용중 활성화응고시간은 시간경과에 따라 길어지는 양상을 보였다. 성인환자에서 저 용량 아프로티닌이 12례(24%)에서 사용되었는데, 이들에서는 심폐바이패스중 활성화응고시간(celite를 활 성물질로 사용)이 비사용군에 비해 높았고, 활성 물질로 kaolin을 사용했을 때의 활성화응고시간은 celite ACT에 비하여 낮게 나타났다. 결론: 결론적으로 헤파린 및 프로타민 고정 용량 투여법은 큰 문제 없이 운용될 수있으나 추가 용량 투여 빈도의 측면에서는 만족할만한 수준은 되지 못하였다.

• 대한환경공학회지
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• 제36권8호
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• pp.579-587
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• 2014

수계에서 검출되는 미량유해물질의 빈도와 종류가 다양해지고 있다. 따라서 정수처리시스템에서 고려되어야 할 부분으로 거론되고 있으며 제거공정과 처리효율에 대한 연구가 활발하게 진행되고 있다. 본 연구에서는 고도처리공정과 나노여과공정을 이용한 제거효율을 평가하였다. 나노여과공정의 경우 물질의 물리화학적 특성에 따라 제거율이 상이하게 나타났다. 물질의 분획분자량이 제거율이 가장 큰 영향을 미치는 것으로 확인되었다. 또한, 원수의 pH보다 높은 pKa 값을 갖거나 Log Kow 값이 2 이하인 물질의 제거효율이 감소되었다. 고도처리공정 중 산화공정에서는 대상물질의 분자량이 클수록 그리고 소수성을 띌수록 산화반응에 의한 제거효율이 감소되었다. 흡착공정에서는 산화되지 않은 대부분의 물질이 제거되었으며 $H_2O_2$에 의하여 산화가 더 잘 진행될수록 흡착반응이 향상되었다.

• 산업경영시스템학회지
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• 제39권3호
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• pp.180-191
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• 2016

Optimizing energy usage for maximum efficiency is an essential goal for manufacturing plants in every industrial manufacturing sector. The generation and distribution of purifying compressed air is a large expense incurred in practically all manufacturing processes. Not only is the generation and treatment expensive equipment of compressed air, but frequent maintenance and effective operation is also required. As a plant's compressed air system is often an integral part of the production process, it needs to be reliable, efficient, and easy to be maintain. In this paper, we study to find operating method to save energy from the adsorption dryer in the process of purifying compressed air, which is required for a clean room production site in "A" company. The compressed air passes through a pressure vessel with two "towers" filled with a material such as activated alumina, silica gel, molecular sieve or other desiccant material. This desiccant material attracts the water from the compressed air via adsorption. As the water clings to the desiccant, the desiccant particle becomes saturated. Therefore, Adsorption dryer is an extremely significant facility which removes the moisture in the air $70^{\circ}C$ below the dew point temperature while using a lot of energy. Also, the energy consumption of the adsorption dryer can be varied by various operating conditions (time, pressure, temperature, etc). Therefore, based on existing operating experiments, we have searched operating condition to maximize energy saving by changing operating conditions of the facility. However, due to a short experiment period (from September to October), further research will be focused on considering seasonality.

• Journal of Applied Biological Chemistry
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• 제52권3호
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• pp.109-115
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• 2009

Xoo로 부터 aspartate aminotransferase로 추정되는 유전자를 분리한 다음 발현시켜 생화학 특성을 조사하였다. 분리된 유전자는 His6 pET-21(a) 운반체에 삽입시켰으며 E. coli BL21(DE3)에서 발현시켰다. 재조합된 Asp-AT는 affinity chromatography를 이용하여 분리하였으며 SDS-PAGE분석에서 43kDa의 단일 밴드를 나타내었다. 분리된 효소는 amino donor 로서 L-aspartate에 대하여 효소활성도가 가장 높았고, L-leucine 및 L-cysteine에 대하여서도 상당한 활성도를 나타내었다. 효소의 최적 pH는 약 7.5 근처에서 나타났고 효소의 안정성은 산성조건 보다는 알칼리 조건에서 훨씬 높았다. 최적 온도는 약 $35-40^{\circ}C$로 나타났고 $55^{\circ}C$에서 20분간 열처리한 이후의 잔여 활성도는 약 78%로 나타났다. 여러 중금속 중에서 망간 이온에 의해 효소활성이 촉진되었다.

• 한국재료학회지
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• 제29권12호
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• pp.774-780
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• 2019

The performance of Li-ion hybrid supercapacitors (asymmetric-type) depends on many factors such as the capacity ratio, material properties, cell designs and operating conditions. Among these, in consideration of balanced electrochemical reactions, the capacity ratio of the negative (anode) to positive (cathode) electrode is one of the most important factors to design the Li-ion hybrid supercapacitors for high energy storing performance. We assemble Li-ion hybrid supercapacitors using activated carbon (AC) as anode material, lithium manganese oxide as cathode material, and organic electrolyte (1 mol L^-1 LiPF₆ in acetonitrile). At this point, the thickness of the anode electrode is controlled at 160, 200, and 240 ㎛. Also, thickness of cathode electrode is fixed at 60 ㎛. Then, the effect of negative and positive electrode ratio on the electrochemical performance of AC/LiMn₂O₄ Li-ion hybrid supercapacitors is investigated, especially in the terms of capacity and cyclability at high current density. In this study, we demonstrate the relationship of capacity ratio between anode and cathode electrode, and the excellent electrochemical performance of AC/LiMn₂O₄ Li-ion hybrid supercapacitors. The remarkable capability of these materials proves that manipulation of the capacity ratio is a promising technology for high-performance Li-ion hybrid supercapacitors.