• 한국수소및신에너지학회논문집
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• 제33권5호
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• pp.598-606
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• 2022

With the advancement of industry, the use of various sustainable energy sources and solutions to problems affecting the environment are being actively requested. From this point of view, it is intended to directly burn unused biogas to use it as energy and to solve environmental problems such as greenhouse gases. In this study, a new type of cavity matrix combustor capable of low-emission complete combustion without complex facilities such as separation or purification of biogas produced in small and medium-sized facilities was proposed, and CFD numerical calculation was performed to understand the performance characteristics of this combustor. The cavity matrix combustor consists of a burner with a rectangular porous microwave receptor at the center inside a 3D cavity that maintains a rectangular parallelepiped shape composed of a porous plate that can store heat in the combustor chamber. As a result of numerical calculation, the biogas supplied to the inlet of the combustor is converted to CO and H₂, which are intermediate products, on the surface of the 3D matrix porous burner. And then the optimal combustion process was achieved through complete combustion into CO₂ and H₂O due to increased combustibility by receiving heat energy from the microwave heating receptor.

• 한국정보과학회논문지:시스템및이론
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• 제35권2호
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• pp.66-74
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• 2008

내장형 시스템은 민감한 데이타를 다루고 저장하기 때문에 정보를 암호화하여 보호하는 암호화 파일 시스템이 필요하지만, 암호화 파일 시스템 적용은 성능 저하가 크기 때문에 내장형 시스템에는 널리 적용되지 못하였다. 기존의 암호화 파일 시스템은 시스템 구조상 불필요한 성능저하를 가져온다. 본 논문에서 제안하는 ISEA(Indexed and Separated Encryption Approach)는 이러한 불필요한 성능 저하를 제거하고, 시스템이 효율적으로 암복호화를 지원하는 새로운 암복호화 기법이다. ISEA는 암호화와 복호화를 페이지 캐쉬를 기준으로 서로 다른 계층에서 수행한다. 즉, 암호화는 페이지 캐쉬 하위 계층에서 수행하고 복호화는 페이지 캐쉬 상위 계층에서 수행한다. 복호화한 내용은 페이지 캐쉬에 저장하여 후속 I/O 요구에 사용할 수 있게 한다. 또한, ISEA는 페이지를 암호화 블록 단위로 나누어 관리하는 페이지 인덱싱 기법을 제공한다. 페이지 인덱싱은 필요에 따라 페이지를 부분적으로 복호화하여 불필요한 복호화 연산을 제거한다. 페이지 캐쉬 탐색 성공률과 읽기/쓰기 사이즈를 종합한 성능 평가에서 ISEA는 효율적인 성능개선을 보여준다.

• 한국의류학회지
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• 제23권3호
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• pp.361-372
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• 1999

The main objectives of this study were to investigate the characteristics of clothing buying behavior under the refund policy of stores (CCBBURPS) and the influence variables on CCBBURPS and to build the model of CCBBURPS. Additionally frequency and reasons for refund were researched. The interviews with 26 subjects the reviews of previous studies and the empirical investigation were processed for the study. The data was collected from 163 Korean females living in U.S. and analyzed by frequency mean factor analysis {{{{ chi ^2 }}-test, t-test and regression. The following results were found : the easyness of decision making (EDM) the loyalty of refund policy store (LRPS) and the increase of buying (IB) were found as the characteristics of clothing buying behaviors under the refund policy. EDM, LRPS and IB were influenced by clothing attitudes-shopping involvement and perceived buying risk-. The frequency of refund with 10 purchases was usually 0~1 times(38.7%) or 1~2 times (38.7%) The reasons for refund were : size unflattering appearance design com\ulcorner. The model of CCBBURPS was built based on the above findings(fig. 1)

• 자원ㆍ환경경제연구
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• 제9권5호
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• pp.853-876
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• 2000

The purpose of this paper is to come up with the measures for sustainable development of the agricultural sector in store for the strengthened U.N. Framework Convention on Climate Change. We analyze the spillover effects of Methane and Nitrous Oxides taxes (carbon tax) on the Korean agricultural sector. Unlike the other sectors, the agricultural sector has a unique characteristic generating greenhouse gas in the process of production itself even without consuming much fossil fuel. In order to estimate the impacts of those taxes, non-linear optimization method has been used with various assumed scenarios. The production effect, income and' price effect, and greenhouse gas emission reduction effect in the agricultural sector have been estimated through this method. The empirical results show that the paddy sector has a bigger tax effect than the livestock sector. In the paddy sector, the carbon tax has more impacts in the suburban areas than in the rural areas, while the swine farming section in the livestock sector has a conspicuous income effect in the midst of low greenhouse gas emission effect. These results allude us to apply graded tax rates to the crop, the livestock, and the region of different kind. Even if the agricultural sector has a less tax effect when compared with other industrial sectors, an environmental tax might be an effective measure to prevent global warming.

• Journal of Biosystems Engineering
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• 제13권2호
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• pp.28-37
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• 1988

This study was conducted to construct the soil bin system and associated microcomputer-based data acquisition system which is to be used for the effective evaluation of wheel performance. The soil bin system consists of four main parts; soil bin, carriage drive system, test carriage and soil processing carriage. The test carriage was constructed to measure the five performance parameters of testing wheels; pulling forte, motion resistance, sinkage and rotational speed of test wheel, and speed of test carriage. The test wheel is powered by a hydraulic system up to 8 ps. Soil processing carriage was designed to provide uniform test soil condition across the toil bin, and reproduction of soil conditions found satisfiable. The data acquisition system consists of APPLE II PLUS microcomputer, strain amplifier, I/O interface, A/D converter, digital counter and various transducers. It takes about 0.86 seconds to measure a set of performance parameters and store on the floppy disk simultaneously. Series of experiment showed that this system can be used effectively for evaluating the wheel performance associated with soil.

• Food Quality and Culture
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• 제2권1호
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• pp.6-12
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• 2008

This study examined the actual consumption status and consumer preference for juk via questionnaire survey to provide useful basic data for the development of diversified commercial juk products. The survey data were collected from a target number of 450 participants living in the Seoul area. The subjects represented different age groups (over 20 years old) and both genders. Through a market survey based on five different retailers, which included juk-specialty stores, supermarkets, and local shopping marts, 17 kinds of commercial juk were chosen for the survey. Consumption frequency and purchasing factors were examined, along with preferences toward commercial juk products and areas for quality improvement. The results revealed that 54.0% of the respondents consumed commercial juk, and male consumers exceeded female consumers in number. It was also shown that those in their $20^{\circ}{\O}s$ consumed commercial juk products the least as compared to other age groups. With regard to commercial juk preferences by type of production mode, females especially preferred specialty store juk while males preferred retort juk sold in supermarkets or local shopping marts. In addition, 85.7% of the total respondents indicated that commercial juk should be further improved in quality, and they specifically noted possible improvements in the areas of 'choice diversification' and 'healthy juk' products. Therefore, one can conclude that by making such improvements, increase in consumption and further diversification of commercial juk products could be realized.

• 한국기계가공학회지
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• 제18권7호
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• pp.14-21
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• 2019

Large-diameter hydraulic devices such as the hydraulic reservoir in aircraft that serves to balance the hydraulic pressure in the various hydraulic devices in the cabin and to store hydraulic oil are operated by the internal piston systems. However, since this operates in an environment with high temperature and humidity, it may cause the inner surface to flake during its operation. Therefore, an anodizing surface treatment is applied to improve the corrosion resistance, abrasion resistance, and smooth operation. However, anodizing increases the surface roughness. Accordingly, the polishing process that improves the surface roughness after anodizing is important. However, the existing polishing process is performed manually, which results in an inefficient process. Therefore, in this study, we selected the optimum polishing conditions for effective polishing using the experimental design to improve the polishing process for the $Al_2O_3$ film that forms after anodization. Through experiments, we confirmed that the surface uniformity after polishing was superior as the feed rate was slower when the same polishing time had been applied.

• 한국해양환경ㆍ에너지학회지
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• 제12권3호
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• pp.217-226
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• 2009

발전소 및 제철소 등 대규모 발생원에서부터 포집한 $CO_2$ 혼합물을 파이프라인이나 선박 등을 통해 수송하고, 이를 해양의 퇴적층에 수백-수천 년 이상 장기간 격리 및 관리하는 $CO_2$ 해양지중저장기술이 기후변화 대응기술로서 국내외적으로 주목 받고 있다. 본 CO2 저장기술을 구현하기 위한 수송 및 저장 공정에 대한 기존의 연구는 주로 순수 $CO_2$를 대상으로 하여 진행되어 왔다. 그러나 일반적으로 발전소 및 제철소 등에서 포집된 $CO_2$ 혼합물에는 $N_2$, $O_2$, Ar, $H_2O$, $SO_x$, $H_2S$ 등과 같은 불순물들을 포함하고 있다. 이러한 $CO_2$ 혼합물 내 불순물들은 처리하고자 하는 $CO_2$ 혼합물의 열역학 상태량 등을 변화시킴으로써 압축, 정제, 수송 및 저장 공정들에 커다란 영향을 미칠 수 있다. 본 논문에서는 이러한 불순물 중 불활성 가스인 $N_2$가 포함된 $CO_2$ 혼합물의 수송 및 저장 공정을 설계하는데 있어 매우 중요한 $CO_2$ 혼합물의 열역학 거동을 모사하기 위한 열역학 상태방정식들을 비교 분석하였다. 또한, $CO_2$, $N_2$와 같은 서로 다른 분자간의 상호작용 효과를 보완하기 위하여 사용되는 이성분 매개변수에 대한 최적 값을 도출하였다.

• The Korean Journal of Physiology
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• 제22권1호
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• pp.13-29
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• 1988

In order to elucidate the regulatory mechanism of intracellular calcium ion concentrations, contractions or contractures induced by $Na^{+}-removal$, calcium-application or ouabain-treatment as an index of $Na^+/Ca^{2+}$ exchange activity were studied in atrial muscle or vascular smooth muscle (aorta and renal artery) of the rabbit. The magnitude of low sodium contractures in atrial trabeculae increased with sigmoid shape when external sodium concentrations were reduced to sodium-free condition, whereas that of calcium contracture intensified in a parabolic pattern when external calcium concentrations were elevated to 8 mM. $Na^{+}-removal$ contractures were induced in a duration-dependent manner to $K^{+}-free$ exposure and same findings were observed with ouabain treatment. $Na^{+}-free$ contractures were not affected by verapamil treatment, but stimulated by $100{\mu}M\;Mn^{2+}$ and inhibited by high concentrations of $Mn^{2+}\;(2{\sim}8mM)$ in a dose-dependent manner. Ryanodine which is known to suppress the release of calcium from internal store abolished spontaneous twitch contractions induced by $K^{+}-free$ solution, but had no effect on the development $Na^{+}-free$ contractures. Na-free contractures were not always induced in vascular smooth muscle preparations. Contractures by $O\;mM\;Na^+$ were usually seen in aorta, but not often in renal artery.$50\;mM\;K^+$, noradrenaline (NA) and angiotensin II (AII) always evoked very large contraction in all preparations of vascular smooth muscle. Contractures developed by $O\;mM\;Na^+$ were not sensitive to verapamil treatment as in atrial trabeculae, but were abolished by $100{\mu}M\;Mn^{2+}$. In contrast to $Na^{+}-free$ contractures, $Mn^{2+}(100{\mu}M)$ had no effect on the contractures induced by NA or 50 mM$K^+$. Caffeine in the concentration of 10 mM evoked transient contracture in the distal renal artery. The rate of spontaneous relaxation in caffeine contracture was dependent upon the concentrations of external sodium, and had double component of relaxation when the rate of relaxation was plotted in the semilogarithmic scale of relative tension versus time. Especially late components of relaxation had more direct relation to $Na^+$ concentrations. It could be concluded that $Na^+/Ca^{2+}$ exchange mechanism in the heart has a large capacity, inhibited by $Mn^{2+}$ but not by verapamil and ryanodine, while $Na^+/Ca^{2+}$ exchange system in vascular smooth muscle has a very low capacity especially in small artery, inhibited by low concentration of $Mn^{2+}\;(100{\mu}M)$ but not affected by verapamil and ryanodine.

• 생물환경조절학회지
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• 제23권2호
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• pp.116-122
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• 2014

본 연구는 방울토마토의 MA 저장시 저장기간 연장과 품질 유지를 위한 비천공 breathable 필름 종류를 구명하고자 진행되었다. 강원도에 위치한 플라스틱 하우스에서 수경재배한 토마토를 담적색기에 수확하여 $5^{\circ}C$, $11^{\circ}C$, 그리고 $24^{\circ}C$에서 산소투과도가 각기 다른 비천공 breathable 필름(10,000; 20,000; 40,000; 60,000; 80,000; $100,000cc/m^2.day.atm$)과 천공필름으로 포장하여 저장하였다. 저장 중 생체중 감소율은 세가지 온도 모두에서 모든 비천공 breathable 필름처리구에서는 0.6%미만이었으나, 천공필름은 $5^{\circ}C$는 2.93%, $11^{\circ}C$는 13.29%, 그리고 $24^{\circ}C$에서는 27.24%에 달하였다. 포장내 이산화탄소와 산소 농도를 볼 때 $5^{\circ}C$와 $11^{\circ}C$에서 20,000 cc 필름, $24^{\circ}C$에서 40,000 cc 필름이 MA 조건에 근접한 수치를 보였다. 에틸렌 농도는 산소투과도가 가장 낮은 10,000 cc에서 모든 온도에서 가장 높았다. 저장 중 외관상 품질과 최종일에 측정한 경도와 당도는 $5^{\circ}C$와 $11^{\circ}C$의 20,000 cc 필름, $24^{\circ}C$의 40,000 cc 필름이 높은 수치를 나타내었다. 그러나 산도와 비타민 C 함량은 필름처리에 대한 일정한 경향을 보이지 않았다. 이상의 결과로 보았을 때, MA 저장시 포장내 대기조성과 저장 종료일의 과실 품질 등을 비교한 결과 방울토마토는 $5^{\circ}C$와 $11^{\circ}C$에서 20,000 cc 필름, $24^{\circ}C$에서는 40,000 cc 필름이 적합하였다.