• Resources Recycling
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• v.14 no.4 s.66
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• pp.47-52
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• 2005

Carbonate species in aqueous solution play an important role in the determination of chemical properties of water in relation with alkalinity, buffer capacity, biological productivity, and so on. These compounds also have reactive characteristics such as interphasal reactions between solid, liquid, and gas phases. In the absence of solid materials, the total amount and relative abundance of each carbonate species are directly influenced by the partial pressure of $CO_2$ gas in the atmosphere, which in turn significantly affects the properties of aquatic system. In the water/wastewater treatment process along with the wastes treatment and recycling process which occurring in aquatic environment, it is essential to figure out its characteristics for their optimization and one of its most influential features upon these processes is determined by carbonate species. To understand the fundamental aspect of the relationship between the partial pressure of $CO_2$ gas and chemical features of water, especially pH, the working partial pressure of pure $CO_2$ gas that produced by contacting the dry ice with water has been estimated based on equilibrium calculation. The equilibrium constants for the dissociation ot carbonic acid were determined using van't Hoff equation and the distribution diagram of carbonate species according to the pH has been constructed to substantiate the results of equilibrium calculation. The estimated working partial pressure of pure $CO_2$ gas was found to be a function of the concentration of carbonates in solution, which suggesting that Prior evaluation of the working partial pressure of gas is essential for a better understanding of aquatic interactions.

• Journal of Veterinary Clinics
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• v.32 no.2
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• pp.215-217
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• 2015

There was no study on the prevalence of doping control of racehorses in Korea. The purpose of this study was to determine prohibited substances in horse races of a drugs testing program. Blood samples were taken from those 298,543 starters prior to racing and the that finished top 3 runners of each race and horses designated by the stewards shall be taken for collection of 91,482 urine samples for the purpose of post-race doping test in Seoul, Busan and Jeju Race Park between 2002 and 2013. Detection and measurement of prohibited substances were carried out by ELISA, GC/MS and LC/MS using standard methods at the Doping Control Center, Korea Racing Authority. Total 0.0030% of pre-races and total 0.0186% of post-races tested positive for prohibited substances. In pre- and post-race, caffeine and ketoprofen were the most detected prohibited substance respectively. We thought that characteristics of pharmacokinetics and pharmacodynamics of drugs resulted in different between plasma and urine. These substances have also been detected with other prohibited drugs suggesting that unintentional feeding or bedding may be the reason and groomers' confusion of candidate horses based by the stewards' research.

• Journal of the Korean Vacuum Society
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• v.16 no.4
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• pp.279-285
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• 2007

We have demonstrated structural evolution and optical properties of the Si-NWs on Si (111) substrates with synthesized nanoscale Au-Si islands by rapid thermal chemical vapor deposition(RTCVD). Au nano-islands (10-50nm in diameter) were employed as a liquid-droplet catalysis to grow Si-NWs via vapor-liquid-solid mechanism. Si-NWs were grown by a mixture gas of $SiH_4\;and\;H_2$ at pressures of $0.1{\sim}1.0$Torr and temperatures of $450{\sim}650^{\circ}C$. SEM measurements showed the formation of Si-NWs well-aligned vertically for Si (111) surfaces. The resulting NWs are 30-100nm in diameter and $0.4{\sim}12um$ in length depending on growth conditions. HR-TEM measurements indicated that Si-NWs are single crystals convered with about 3nm thick layers of amorphous oxide. In addition, optical properties of NWs were investigated by micro-Raman spectroscopy. The downshift and asymmetric broadening of the Si optical phonon peak with a shoulder at $480cm^{-1}$ were observed in Raman spectra of Si-NWs.

• Korean Journal of Food Science and Technology
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• v.12 no.3
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• pp.200-204
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• 1980

A series of tests ware conducted to find out whether continuous heat bleaching of the refined Malaysian plam oil stored in different conditions could reduce color of the finished oil in an actual plant situation. When the refined oil was stored in a stainless steel tank and was not abused by heat during 5 month storage period, heat bleaching followed by clay bleaching and deodorization resulted in a substantial reduction in color of the finished oil in comparison to conventional process (clay bleaching of the refined oil followed by deodorization) (2.6 vs 1.3 red in Lovibond color). However, when the refined oil was stored in a carbon steel tank and was highly abused by heat in the presence of iron picked up from the tank (6.53 ppm) during the same storage period, heat bleaching followed by clay bleaching and deodorization did not help reduce color of the finished oil in comparison to the conventional process (2.7 vs 2.8 red in Lovibond color). It was also shown that oxidation values were not good indices for heat bleachability. Heat bleaching caused slight increase in polymer content of the oil. However, trans isomers were not increased when the oil was heat bleached.

• Economic and Environmental Geology
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• v.40 no.5
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• pp.563-574
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• 2007

Laser induced breakdown spectroscopy (LIBS) is a recently developed analytical technique that is based upon the measurement of emission lines generated by atomic species close to the surface of the sample, thus allowing their chemical detection, identification and quantification. With powerful advantages of LIBS compared to the conventional analytical methodology, this technique can be applied in the detection of heavy metals in the field. LIBS allows the rapid analysis by avoiding laborious chemical steps. LES have already been applied for the determination of element concentration in a wide range of materials in the solid, liquid and gaseous phase with simplicity of the instrument and diversity of the analytical application. These feasibility of rapid multi elemental analysis are appealing proprieties for the in-situ analytical technique in geochemical investigation, exploration and environmental analysis. There remain still some limitations to be solved for LIBS to be applied in soil environment as an in-situ analytical technology. We would like to provide the basic principle related to the plasma formation and laser-induced breakdown of sample materials. In addition, the matrix effect, laser properties and the various factors affecting on the analytical signal of LIBS was dealt with to enhance understanding of LIBS through literature review. Ultimately, it was investigated the feasibility of LIBS application in soil environment monitoring by considering the basic idea to enhance the data quality of LIBS including the calibration method for the various effects on the analytical signal of LIBS.

• Journal of the Korean Society of Marine Environment & Safety
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• v.20 no.1
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• pp.96-103
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• 2014

A liquefied natural gas(LNG) in cryogenic liquid is converted back into gaseous form for distribution to residential and industrial consumers. In this re-gasification process, LNG supplies a plenty of cold thermal energy about $83.7{\times}10^4kJ/kg$. The LNG cold thermal energy is utilized for the re-liquefaction process of cryogenic fluids such as Nitrogen, Hydrogen and Helium, and ice manufacturing process and air-conditioning system in some advanced countries. Therefore, it is also necessary to establish the recovery systems of the LNG cold thermal energy around Incheon, Pyungtaek and Tongyung LNG import terminals in our country. Methane is used as working fluid in this paper, which is the major component of LNG over 85 % by volume, in order to investigate the flow behavior characteristics of LNG with phase change at low heat flux. This paper presents the effects of pipe diameters, pipe inclinations and saturation pressures on the flow boundaries of methane flowing in a cryogenic heat exchanger tube, together with those of nitrogen, propane, R11 and R134a. The outcomes obtained from this theoretical researches are also compared with previous experimental data. It was also found that the effect of pipe inclination on the methane flow boundaries was significant.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2003.05a
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• pp.244-245
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• 2003

고체나 액체 추진로켓에 비하여 하이브리드 추진 시스템은 작동조건의 안정성과 안전함등의 많은 장점을 가지고 있다. HTPB와 같은 고체연료는 제작 및 저장, 운송 그리고 장착상의 안정성을 가지고 있으며 하이브리드 로켓의 고체연료로의 산화제의 유입을 제어하면서 추력의 변화와 엔진내부의 연소중단과 재 점화를 용이하게 할 수 있다. 이러한 이유로 인하여 하이브리드 엔진은 좀 더 경제적인 장치로 기대를 모으고 있다. 그러나, 기존의 하이브리드 로켓 엔진은 고체 추진 로켓에 비하여 낮은 연료 regression 율과 연소효율을 가지는 단점이 있다. 이러한 단점을 해결하고 요구되어지는 추력값과 연료유량을 증가시키기 위하여 고체연료의 표면적을 증가시킬 필요가 있다. 기존의 하이브리드 엔진에서는 연료 그레인에 다수의 연소포트를 만들어 표면적을 증가시켰으나 이는 비 활용 공간의 증가와 추진제의 질량 및 체적분율의 상당한 감소를 초래한다. 지난 수십년간에 걸쳐 하이브리드 엔진에서 연료의 regression 특성 및 엔진 성능 향상을 위한 연구가 계속되어 왔으며 최근에 엔진의 체적 규제를 경감시키고 연료의 regression율을 향상시키기 위하여 선회유동을 이용하는 하이브리드 로켓 엔진들이 제안되고 있다. 이러한 선회유동을 가지는 하이브리드 로켓은 고체연료 그레인에 대하여 평행하게 유입되는 기존의 하이브리드 로켓에 비하여 고체연료 벽면에서의 대류열전달이 현저하게 증가하게 되어 아주 높은 고체연료의 regression율을 얻을 수 있는 이점이 있다. 선회유동 하이브리드 로켓의 연소과정은 고체 연료의 열분해과정, 대류 열전달, 난류 혼합, 난류와 화학반응의 상호작용, soot의 생성 및 산화과정, soot 입자 및 연소가스에 의한 복사 열전달, 연소장과 음향장의 상호작용 등의 복잡한 물리적 과정을 포함하고 있다. 이러한 물리적 과정 중 난류연소, 고체연료 벽면 근방에서의 대류 열전달 및 연소과정에서 생성되는 soot 입자로부터의 복사 열전달, 그리고 고체연료 열 분해시 표면반응들은 고체연료의 regression율에 큰 영향을 미친다. 특히 고체연료의 난류화염면의 위치와 폭, 그리고 비 예혼합 난류화염장에서 생성되는 soot의 체적분율의 예측은 난류연소모델, 열전달 모델, 그리고 regression율 모델에 의해 크게 영향을 받기 때문에 수치모델의 예측 능력 향상시키기 위하여 이러한 물리적 과정을 정확히 모델링해야 할 필요가 있다. 특히 vortex hybrid rocket내의 난류연소과정은 아래와 같은 Laminar Flamelet Model에 의해 모델링 하였다. 상세 화학반응 과정을 고려한 혼합분율 공간에서의 화염편의 화학종 및 에너지 보존 방정식은 다음과 같다. 화염편 방정식과 혼합분률과 scalar dissipation rate의 관계식을 이용하여 혼합분률과 scalar dissipation rate에 따른 모든 reactive scalar들을 구하게 된다. 이러한 화염편 방정식들을 mixture fraction space에서 이산화시켜서 얻은 비선형 대수방정식은 TWOPNT(Grcar, 1992)로 계산돼 flamelet Library에 저장되게 된다. 저장된 laminar flamelet library를 이용하여 난류화염장의 열역학 상태량 평균치는 presumed PDF approach에 의해 구해진다. 본 연구에서는 강한 선회유동을 가지는 Hybrid Rocket 연소장내의 난류와 화학반응의 상호작용을 분석하기 위하여 Laminar Flamelet Model, 화학평형모델, 그리고 Eddy Dissipation Model을 이용한 수치해석결과를 체계적으로 비교하였다. 또한 Laminar Flamelet Model과 state-of-art 물리모델들을 이용하여 선회 유동을 갖는 하이브리드 로켓 엔진의 연소 및 Soot 생성 및 산화과정을 살펴보았으며 복사 열전달이 고체 연료 표면의 regression율에 미치는 영향도 살펴보았다. 특히 swirl강도, 산화제의 유입위치 그리고 선회유동의 형성방식이 하이브리드 로켓의 연소특성 및 regression rate에 미치는 영향을 상세히 해석하였다.

• Journal of the Korean Chemical Society
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• v.39 no.11
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• pp.869-877
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• 1995

Carbonation process of Jung sun slake lime$(Sr(OH)_2=0.053 wt%)$ suspension with $CO_2$ gas at 30∼80$^{\circ}C$ has been studied to investigate the formation process of aragonite. The reaction temperature at above $50^{\circ}C$, rhombic nuclei of $SrCO_3$ has been grown with the interaction of $CO_3^{2-}$(aq) which is profitable to growth the nuclei at the liquid film of gas-liquid interface to form pillar aragonite crystal. At $40^{\circ}C$, the controlling of concentration of $CO_2$(aq) at the beginning of the reaction has been made the nuclei to growth to be an aragonite crystal. Addition of some $Sr(OH)_2$ to Yi Lee slake lime $(Sr(OH)_2=0.011 wt%)$ suspension and controlling the concentration of $OH^-$(aq) and $CO_2$(aq), the carbonation reaction produced pillar aragonite crystal with the short side of 0.1∼0.2 ${\mu}m$ and long side of 1∼2 ${\mu}m.$

• Korean Journal of Food Science and Technology
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• v.16 no.2
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• pp.192-200
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• 1984

Total lipid contents in rice bran for Poong-San(Tongil) and Dong-Jin(Japonica) were 16.13% and 16.97%, respectively. Neutral lipids for Pong-San(75.20%) were slightly higher than those for Dong-Jin(73.69%), whereas contents of glycolipid for Poong-San(16.71%) were lower than those for Dong-Jin(22.80%). Contents of phospholipid in Poong-San(8.09%) were much higher than those in Dong-Jin(3.51%). Acid, peroxide and thiobarbituric acid value of total lipids extracted from rice bran of Poong-San were slightly lower than those of Dong-Jin. Iodine value showed the reverse trend. The neutral lipids were fractionated and identified as hydrocarbon, esterified sterol, triglyceride, free fatty acid, free sterol, diglyceride and monoglyceride. Triglyceride contents were less than common edible oils, but diglyceride and monoglyceride contents were higher. Among the glycolipids contained in the polar lipids, esterified sterylglycoside(11.46%) was the most abundant. Of the phospholipids, phosphatidyl ethanolamine, phosphatidyl inositol and phosphatidyl choline were the major components. Main fatty acids in the total lipids, three lipid components and stepwise eluted individual lipids were olelic acid, linoleic acid and palmitic acid. The fatty acid composition of the neutral lipids was similar to that of the total lipids. In glycolipids, the content of linoleic acid was higher than that of oleic acid, and palmitic acid was predominant in the fatty acid composition of the esterified sterylglycoside.

• Korean Journal of Food Science and Technology
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• v.11 no.4
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• pp.298-303
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• 1979

The composition of the neutral lipids in the free and bound lipids from four varieties of experimentally cultivated potatoes were identified and quantified by thin layer- and gas-liquid chromatographies. The results were summarized as follows ; 1. The neutral lipids contained in the free and bound lipids were fractionated and identified as esterified sterol, triglyceride, diglyceride, free fatty acid, and free sterol, of which triglyceride and esterified sterol were most abundant. Meanwhile, the triglyceride and esterified sterol contents in the free lipid to the total lipid quantity were 10 and 2.7 % respectively, approximately 3 times higher than the 3.0 and 0.8 % contained in the bound lipid. 2. The fatty acid composition of the neutral lipids in the free and bound lipids was the same as that of the total free and bound lipids. The only difference was that content of saturated fatty acid was lower rate in the neutral lipid of the free lipid than in the total free lipid, whereas the unsaturated fatty acid was more abundant in the neutral lipid of the free lipid. Fatty acid composition of individual neutral lipid was of almost the same pattern as that of the total neutral lipid.