• 대한기계학회:학술대회논문집
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• 대한기계학회 2004년도 춘계학술대회
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• pp.1830-1834
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• 2004

In this paper, we present scavenge characteristics in a small subchamber of HCCI. It is very important to enhance scavenge rate because ignition in a chamber sometimes does not happen. To understand this phenomenon numerical tool was performed using the FLUENT which is a commercial code. Focus is given to the effect on the scavenge rate of the geometric factor that is the angle of nozzle injection. The numerical results show that the scavenge ones in the subchamber heavily depend on the nozzle angle. It was found that the scavenge rate is more effective at angled nozzle.

• 한국전산유체공학회지
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• 제10권2호
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• pp.21-29
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• 2005

In this paper, we present the theoretical and numerical results of scavenge characteristics in a small subchamber of an HCCI(Homogeneous Charge Compression Ignition) engine. Two theoretical models are proposed in prediction of the scavenge time and the efficiency; one is the non-mixing model in which the input gas(CH4) and the existing gas(air) do not mix at all, and the other is the fully-mixed model in which the two gases are assumed to mix completely before ejection. Focus is also given to the effect on the scavenge performance of the size of the chamber outlet.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2004년도 추계학술대회
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• pp.1401-1406
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• 2004

In this paper, we present the theoretical and numerical results of scavenge characteristics in a small prechamber of an HCCI(Homogeneous Charge Compression Ignition) engine. Two theoretical models are proposed in prediction of the scavenge time and the efficiency ; one is the non-mixing models in which it is assumed that the input gas($CH_{4}$) and the existing gas(air) do not mix with each other, and the other is the fully-mixed model in which the two gases are assumed to mix completely before ejecting to the ambient air. Focus is also given to the effect on the scavenge performance of the size of the chamber oulet.

• 미생물학회지
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• 제49권4호
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• pp.403-414
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• 2013

양배추 피클로부터 분리된 유산균으로 발효하여 제조한 플레인 요구르트와 소이 요구르트를 저장하는 동안 미생물학적 및 물리화학적 변화와 항산화 특성을 조사하였다. 분리 균주는 당분해능과 유전자 염기서열 분석을 통해 L. casei PC05와 L. acidophilus PC16으로 동정되었다. Lactobacillus acidophilus PC16 균주로 발효시킨 요구르트의 적정산도, 점도 및 균수는 L. casei PC05 균주에 의해 제조된 요구르트에 비해 높게 나타났으며, 특히 플레인 요구르트보다 소이 요구르트에서 세균수와 물리화학적 요인의 측정값이 유의하게 높은 것으로 확인되었다. 한편, L. acidophilus PC16 균주로 발효시킨 요구르트는 DPPH 라디칼 소거능과 철이온 킬레이팅 활성이 높았으나, L. casei PC05 균주의 요구르트는 superoxide anion 제거능과 SOD 활성이 높은 것으로 나타났다. 대부분의 항산화능은 플레인 요구르트보다 소이 요구르트에서 더 높게 나타났으며, 요구르트의 지질과산화 억제능은 항산화 활성에 기인하는 것으로 추정된다. 또한 발효직후 요구르트의 미생물학적, 물리화학적 및 항산화 활성은 $4^{\circ}C$에서 8일간 저장하는 동안 거의 일정한 수준으로 유지되었다.

• 대기
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• 제29권5호
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• pp.609-614
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• 2019

Cloud seeding experiment has been proposed as a way to alleviate severe air pollution problem because, if successful, artificially produced precipitation through cloud seeding could scavenge out some portion of air pollutants. As a first step to verify the practicality of such experiment, seedability of the clouds observed in Seoul is assessed by examining statistical characteristics of some relevant meteorological variables. Analyses of 9 years of Korea Meteorological Agency Seoul station data indicate that as PM₁₀ mass concentration increases, cloud amount, liquid water path, and ice water path decrease, but the difference between temperature and dew point temperature tends to increase. Such finding suggests that cloud seeding becomes less feasible as air pollution becomes more severe in the Seoul metropolitan area, at least in a statistical sense. For some individual severe air pollution events, however, seedable clouds may exist and indeed cloud seeding experiments can be successful. Therefore, detailed investigation on cloud seedability for individual severe air pollution events are highly required to make a concrete assessment of cloud seeding as a way to alleviate severe air pollution problem.

• 한국수소및신에너지학회논문집
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• 제23권5호
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• pp.437-447
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• 2012

Ceria ($CeO_2$) was used to scavenge free radicals which attack the membrane in the polymer electrolyte membrane water electrolysis (PEMWE) circumstance and to increase the duration of the membrane. In order to improve the electrochemical, mechanical and electrocatalytic characteristics, engineering plastic of the sulfonated polyether ether ketone (SPEEK) as polymer matrix was prepared in the sulfonation reaction of polyether ether ketone (PEEK) and the organic-inorganic blended composite membranes were prepared by sol-gel casting method with loading the highly dispersed ceria and cesium-substituted tungstophosphoric acid (Cs-TPA) with cross-linking agent contents of 0.01 mL. In conclusion, CL-SPEEK/Cs-TPA/ceria (1%) membrane showed the optimum results such as 0.130 S/cm of proton conductivity at $80^{\circ}C$, 2.324 meq./g-dry-membrane of ion exchange capacity and mechanical characteristics, and 65.03 MPa of tensile strength which were better than Nafion 117 membrane.

• 한국축산식품학회지
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• 제41권6호
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• pp.1036-1048
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• 2021

This study investigated the possible improvement in the antioxidative status and quality characteristics of ready-to-eat (RTE) Samgyetang after adding various black garlic (BG) extracts. The antioxidant activity, total phenolic content (TPC), total flavonoid content (TFC), meat quality indexes, and lipid oxidation rates were measured after receiving one of five different treatments consisting of conventional Samgyetang broth as a negative control, raw garlic (RG) extract as a positive control, BG, oven-dried BG, and maltodextrin-encapsulated BG extract as treatments. Employing retort cooking, fat trimmed carcasses were added to the initially prepared broth together with a phenolic extract that was set at 5% (w/w). A significant intensification of red and yellow color was observed in breast and thigh meat treated with BG extracts, regardless of pretreatment, compared to the negative control and RG. The moisture percentage was affected by the addition of BG extracts, where the encapsulation group retained the highest water content after retorting. In terms of antioxidative status, maltodextrin-encapsulated BG extract was as effective as an oven-dried extract to scavenge free radicals and showed the highest score among samples (p<0.01). The concentration of TFC was found to be the highest and did not differ between encapsulation and oven-dried groups, followed by BG, RG, and the negative control. However, the addition of encapsulated BG extract was the most effective in delaying the formation of malondialdehyde among the samples. Therefore, pre-treatment of BG extract through encapsulation is recommended to develop a higher antioxidative status and quality characteristics of Samgyetang.

• 동력기계공학회지
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• 제12권4호
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• pp.5-11
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• 2008

The RI gasoline engine haying a sub-chamber had a high cycle variation due to the difficulty of the residual gas scavenge in the sub-chamber. To solve this problem and improve the combustion performance of RI engine, we devised a method to inject directly CNG fuel into the sub-chamber. A DI diesel engine of single cylinder was converted into a RI-CNG engine and an electronic control unit for the engine was manufactured. In this study, the combustion characteristics of the RI-CNG engine were investigated with the injection timings and air excess ratios at the load conditions of 50% throttle open rate and 1700rpm. As the results from this study, the RI-CNG engine worked reliably under the condition of the ignitable lean limit of $\lambda=1.7$ by showing the $COV_{imep}$ below about 5%. And the highest thermal efficiency could be obtained in the injection timing that produced the high imep and the low $COV_{imep}$ at the same time. The CO emission concentration indicated very low values and the THC and $NO_x$ showed an opposite pattern. With a view to improving the thermal efficiency and reducing the harmful emissions, the proper control region of the ignition timing and the mixture ratio were nearly ATDC $20^{\circ}\sim50^{\circ}$ and $\lambda=1.4$ respectively.

• 한국수소및신에너지학회논문집
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• 제25권2호
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• pp.151-160
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• 2014

CL-SPEEK/Cs-TPA/$CeO_2$ composite membrane was prepared for polymer electrolyte membrane water electrolysis (PEMWE). In order to improve the electrochemical, mechanical, durabilities and electrocatalytic characteristics, engineering plastic of polyether ether ketone (PEEK) as polymer matrix was sulfonated and the organic-inorganic blend composite membranes was prepared by loading cesium-substituted tungstophosphoric acid (Cs-TPA) by titration method with cross-linking agent contents of 0.01mL. Ceria ($CeO_2$) was used to scavenge free radicals which attack the membrane in the PEMWE circumstance and to increase the duration of the membrane. CL-SPEEK/$Cs_{(1)}$-TPA/CeriaIn conclusion, 1% membrane showed the optimum results such as 0.119 S/cm at $80^{\circ}C$ of proton conductivity and 62MPa of tensile strength.

• 한국수소및신에너지학회논문집
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• 제25권1호
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• pp.1-10
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• 2014

Ceria ($CeO_2$) was used to scavenge free radicals which attack the membrane in the polymer electrolyte membrane water electrolysis (PEMWE) circumstance and to increase the duration of the membrane. In order to improve the electrochemical, mechanical and electrocatalytic characteristics, engineering plastic of the sulfonated polyether ether ketone (SPEEK) as polymer matrix was prepared in the sulfonation reaction of polyether ether ketone (PEEK) and the organic-inorganic blended composite membranes were prepared by sol-gel casting method with loading the highly dispersed ceria and cesium-substituted phophomolybdic acid(Cs-MoPA) with cross-linking agent contents of 0.01mL. In conclusion, CL-SPEEK/$Cs_{(2.5)}$-MoPA/ceria(1%) membrane showed the optimum results such as 0.1095S/cm of proton conductivity at $80^{\circ}C$, 2.906meq./g-dry-membrane of ion exchange capacity and mechanical characteristics, and 49.73MPa of tensile strength which were better than Nafion 117 membrane.