• 플랜트 저널
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• 제15권3호
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• pp.29-34
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• 2019

본 연구에서는 정격 합성가스 생산량이 54.33 kg/s인 태안 IGCC 발전소 가스화기를 대상으로 가스화기 산소부하가 일정한 운전조건에서 석탄 공급량을 고정하고 증기 주입량을 변화시킬 때 증기 주입량이 합성가스 생산량에 미치는 영향을 알아보고자 하였다. 증기 주입량은 가스화기 운전지침서의 증기 주입량 0.28 kg/s 및 0.32 kg/s 까지 변동하며 운전하였고, 최대 합성가스 평균 생산량은 가스화기 산소부하 80 % 및 90 %에서 증기 주입량 0.14 kg/s 및 0.15 kg/s 일 때 측정되었다. 이 연구를 통해 증기 주입량 조정만으로 합성가스 생산량이 변화 하고, 증기 주입량 증가시 합성가스 생산량은 증가하다가 다시 감소하는 특성을 확인 할 수 있었다. 추가 석탄 공급 없이 증기 주입만으로 합성가스 생산량을 증가 시킬 수 있고, 석탄의 성분 및 조성에 따라 가스화기의 합성가스 생산량이 다른 특성을 가지고 있는 것으로 사료되는 바, 시험에서 사용된 카보원 석탄을 사용하는 가스화기는 산소부하 80% ~ 90 %에서 운전시 석탄 버너 당 증기 주입량을 약 0.14 kg/s 에서 운전하는 것이 추천된다.

• 한국환경농학회지
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• 제6권2호
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• pp.53-65
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• 1987

본(本) 연구(硏究)는 1981년(年)부터 1984년(年)까지 4개년(個年)에 걸쳐 울산공업단지주변(蔚山工業團地周邊) 21 개지점(個地點)에서 수행(遂行)되었다. 대기중(大氣中) 황화물(黃化物) 및 불화물(弗化物)이 수도(水稻)의 생육(生育) 및 수량(收量)에 미치는 영향(影響)을 구명(究明)하기 위해 수도(水稻)의 수량구성요소(收量構成要素), 수량(收量), 대기중(大氣中)의 류황산화물(硫黃酸化物), 엽내류황(葉內硫黃) 및 불소함량(弗素含量), 엽피해율(葉被害率)을 조사(調査)하여 검토(檢討)한 결과(結果)는 다음과 같다. 1. 수도(水稻)의 수량(收量)에 대(對)한 수량구성요소(收量構成要素)의 기여율(寄與率)은 주당수수(株當穗數)의 기여율(寄與率)이 매년(每年) 제일 높았으며, 타(他) 수량구성요소(收量構成要素)들의 기여율(寄與率)은 주당수수(株當穗數)보다 현저히 낮았고, 이들의 기여정도(寄與程度)는 조사년도(調査年度)에 따라 차이(差異)가 있었다. 2. 수량(收量)과 주당수수(株當穗數) 및 등열율(登熱率)에 대(對)해서는 매년(每年) 엽내불소함량(葉內弗素含量)에 의한 영향도(影響度)는 엽내류황(葉內硫黃)에 의한 것보다 크고, 수당입수(穗當粒數)에 대(對)한 엽내류황(葉內硫黃)과 불소(弗素)에 의한 영향도(影響度)는 조사년도(調査年度)에 따라 일정(一定)한 경향(傾向)이 없었으며, 이들 오염지표(汚染指標)와 천립중간(千粒重間)에는 상관(相關)의 유의성(有意性)이 인정(認定)되지 않았다. 그리고 수량(收量) 및 수량구성요소(收量構成要素)에 대(對)한 월별(月別) 오염물(汚染物)이 영향(影響)은 조사연도(調査年度)에 따라 차이(差異)가 있었으며, 매년(每年) 주당수수(株當穗數)의 감소(減少)에 가장 큰 영향(影響)을 미친 월별(月別) 오염물(汚染物)이 최종수량(最終收量)의 감소(減少)에도 가장 영향(影響)이 컸다. 3. 수도(水稻)의 수량추정(收量推定)에 적용(適用)할 오염지표(汚染指標)를 선정(選定)할 때 월별(月別) 엽내류황(葉內硫黃) 및 불소함량(弗素含量)과 엽피해율(葉被害率)을 함께 적용(適用)하는 것이 PSS 값이 제일 낮았다. 그리고 PSS에 의해 선정(選定)된 오염지표(汚染指標)를 이용(利用)하여 만든 회귀식(回歸式)에 의한 예측수량(豫測收量)과 실측수량간(實測收量間)에는 높은 상관관계(相關關係)가 인정(認定)되었다.

• 전기화학회지
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• 제10권1호
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• pp.25-30
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• 2007

고분자전해질 연료전지의 성능은 cell 온도, 전체 압력, 반응 기체의 부분 압력 상대습도와 같은 다양한 요인들에 의해 영향을 받는다. 이온화된 수소 이온은 $H_3O^+$의 형태로 membrane을 통과하여 물을 생성하는 반응으로 전기를 발생시킨다. 대용량 연료전지에서는 부수적으로 생성되는 열을 제거하거나 다른 용도로 사용할 목적으로 냉각시스템이 필요하다. 냉각수의 전도도가 상승할 경우에 연료전지에서 발생된 전류의 일부가 냉각수를 통하여 누설되어 연료전지의 성능을 감소시킬 수 있다. 본 연구에서는 3차 증류수와 ethylene glycol이 함유되어 있는 부동액을 사용하여 저항 수치 변화를 관찰하는 실험을 수행하였다. 3차 증류수의 경우 저항값이 설정치 이하로 내려가는데 약 28일이 소요되었고, 연료전지의 운전에 의한 영향은 관찰되지 않았다. 부동액을 냉각수로 사용한 경우는 43일이 지나도 저항값이 설정치 이하로 내려가지는 않았지만, stack 분리판의 접착부에 이상이 생긴 것으로 추정되는 연료전지의 성능 저하가 발생하여 전도도 실험을 중단하였다. 고분자전해질 연료전지에서는 수소이온의 이온전도성 저하를 방지하기 위하여 외부에서 가습하여 주는 방식이 일반적이지만, 소용량 연료전지에서는 무가습 조건을 적용하여 연료전지의 효율을 높이고 제작단가도 경감할 수 있다. 이를 위하여 저가습 및 무가습 실험을 수행하였으나 대용량 연료전지에서는 양측 무가습인 경우에 $50{\sim}60^{\circ}C$ 이상의 고온에서 성능이 발현되기 어려운 것으로 관찰되었다. 냉각수의 유량을 다르게 하여 실험을 수행한 경우에는 0.78L/min과 같은 낮은 유량에서 출구온도와 입구온도를 측정하여 본 결과 두 온도 사이에 ${\Delta}T$가 다른 유량에서보다 크게 발생하여 성능이 감소된 것으로 사료된다. 이와 같이 냉각수의 온도와 유량을 다르게 하여 양측 무가습 실험을 수행한 결과, 연료전지의 성능이 cell 온도에 직접적인 연관이 있는 것으로 관찰되었다.

• Advances in Energy Research
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• 제1권2호
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• pp.147-163
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• 2013

The world faces several issues of energy crisis and environmental deterioration due to over-dependence on single source of which is fossil fuel. Though, fuel is needed as ingredients for industrial development and growth of any country, however the fossil fuel which is a major source of energy for this purpose has always been terrifying thus the need for alternative and renewable energy sources. The search for alternative energy sources resulted into the acceptance of a biofuel as a reliable alternative energy source. This work presents the study of optimization of process of transesterification of vegetable oil to biodiesel using NaOH as catalyst. A $2^4$ factorial design method was employed to investigate the influence of ratio of oil to methanol, temperature, NaOH concentration, and transesterification time on the yield of biodiesel from vegetable oil. Low and high levels of the key factors considered were 4:1 and 6:1 mole ratio, 30 and $60^{\circ}C$ temperatures, 0.5 and 1.0 wt% catalyst concentration, and 30 and 60 min reaction time. Results obtained revealed that oil to methanol molar ratio of 6:1, tranesetrification temperature of $60^{\circ}C$, catalyst concentration of 1.0wt % and reaction time of 30 min are the best operating conditions for the optimum yield of biofuel from vegetable oil, with optimum yield of 95.8%. Results obtained on the characterizzation of the produced biodiesel indicate that the specific gravity, cloud point, flash point, sulphur content, viscosity, diesel index, centane number, acid value, free glycerine, total glycerine and total recovery are 0.8899, 4, 13, 0.0087%, 4.83, 25, 54.6. 0.228mgKOH/g, 0.018, 0.23% and 96% respectively. Results also indicate that the qualities of the biodiesel tested for are in conformity with the set standard. A model equation was developed based on the results obtained using a statistical tool. Analysis of variance (ANOVA) of data shows that mole ratio of ground nut oil to methanol and transesterification time have the most pronounced effect on the biodiesel yield with contributions of 55.06% and 9.22% respectively. It can be inferred from the results various conducted that vegetable oil locally produced from groundnut oil can be utilized as a feedstock for biodiesel production.

• 대한간호학회지
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• 제25권4호
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• pp.617-632
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• 1995

Nowadays, most big hospitals have a computer system to manage their administration. For maxi mum effectiveness in managing the computer system, an analysis of the variables affecting its implementation is necessary from the beginning. This study was done to analyze the variables influencing the operation of a hospital information system (HIS). The theoretical base for this study considered the combined effects of user expectations of computerization, and computer-anxiety. The relationship between variables in the theoretical base were analyzed and the individual characteristics influencing each variable were also analyzed. This study was done in two steps. First, 344 nurses were given an initial questionnaire developed to evaluate the reliability of the items. Based on the results, a second revised questionnaire was administered to 88 nurses who had been working in the areas where HIS was applied. The results of the first and second steps of the study are as follows 1. The initial study was done with nurses who were trained on the computer system briefly before HIS was implemented. The individual characteristics influencing computer anxiety and expectation regarding computer system usage in that initial study included, length of career, type of degree or certification, previous experiences with a computer, training on a computer, desire for computer training, and level of acceptance of a computerized work environment. But in the second study with nurses working in areas of the hospital where HIS was introduced, the work site was the only influencing characteristics. There-fore, in applying a computer system, overcoming work-environment barriers will be more import-ant than any individual characteristics. 2. The computer anxiety of the nurses in both groups, before and after the computer system ap-plication, was below the average level but the expectation of the effects of computerization was above average. The nurses using the computer program showed an above average level of satis-faction with the computer system itself, and with its effect on their efficiency. Therefore, the ability of nurses operating HIS will be positively. predictive. 3. For the variables included in the theoretical framework of the study, all of the correlational coefficients were statistically significant in the analysis of variation correlation. Therefore, the theoretical base of the study, "expectation in con junction with computer anxiety" can be considered an model which can be evaluated. Accord-ing to our analysis, the higher the level of nurses' motivation to use the computer system and the lower the anxiety about computer usage, the higher the possibility of computer system acceptance by nurses. The results of this study showed that in applying a computer system in the hospital, the main characteristic influencing acceptance was where the individual worked rather than personal characteristics such as length of career, type of degree or certification, and previous experiences with a computer. Therefore, it is suggested that the first step in uncovering and eliminating hindrance factors in ap-plication of a computer system should be an analysis of working conditions in relation to the functional content of the computer system. The suitability of the theoretical model based on the hypothesis ap-plied in this study should be further tested.

• 산경연구논집
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• 제9권12호
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• pp.45-53
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• 2018

Purpose - The purpose of the study was to investigate operation system of current convenience store and competing retail store and to find out development of unattended convenience store. Operators can save labor cost and solve labor seeking when opening shop under suitable environment and commerce area, and assure of employee's safety. Customers are allowed to select commodity comfortably without disclosure of face and to shorten standby time at simple store opening, buying and paying and to produce convenient living environment by financing, delivery and goods control. This study examined effect and problems of operation of existing and unattended convenience store from point of view of visual merchandising to find out model of unattended convenience store and to strengthen competitiveness of convenience store business. Research design, data, and methodology - Research procedure of accomplishment of goal of the study was: The study investigated state of distribution business, and role and definition of VMD. First, VMD played an important role of promotion and competitiveness of unattended convenience stores. Second, the author investigated research and cases of unattended convenience stores 14 months, that is to say, from August 15, 2017 to October 15, 2018. Third, the author investigated on-the-spot three of common convenience stores, three of unattended convenience stores and three of retailers one month, that is to say, June 1, 2018 to July 1, 2018. The subject was convenience stores and retailers selling similar type of products at Seoul and metropolitan area. Results - Layout, selling place, brand identity, goods assortment, authentication system, product information cognition and control, buying and payment system, security system, salesmen, promotion and other services should be improved from point of view of merchandising. Structure, furniture, lighting, voice, façade, VP, PP, IP and POP should be developed. Conclusions - Unattended convenience stores saved operating cost and lessened labor and gave visitors convenience and comfortable shopping and made use of resources effectively. Further studies with quantitative analysis shall find out strategic conditions for promotion of unattended convenience stores.

• 멤브레인
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• 제10권1호
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• pp.39-46
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• 2000

분리막 접촉기를 통한 이산화탄소의 흡수거동 예측을 위한 공정모사를 위해 시스템의 흡수제로 탄산칼륨 수용액을 선정하였고, 시스템에서의 이산화탄소와 관련된 가역반응을 고려하였으며, 사용된 반응속도상수, 평형상수, 용해도 그리고 확산계수는 탄산이온의 농도와 온도의 함수로 사용하였다. 또한 분리막 접촉기 공정모사를 위한 조작 조건으로 중공사막의 기공상태는 비젖음성 조건을 선택하였으며, 이러한 조작조건하에서 이산화탄소 분리거동을 다양한 공정변수 즉, 흡수제의 농도와 유속, 혼합기체의 압력변화에 대해 고찰하였다. 흡수제의 농도가 증가함에 따라 촉진수송에 의한 이산화탄소의 흡수거동을 확인할 수 있었고, 흡수제의 유속 증가에 따라 이산화탄소의 흡수속도가 점차 증가함을 확인할 수 있었으며, 분리막 접촉기에서 혼합기체의 압력변화가 흡수속도에 미치는 영향 및 흡수제의 재사용에 따른 흡수속도를 확인할 수 있었다. 이러한 공정모사를 통해 분리막 접촉기의 구성 및 조작에 필요한 각각의 인자들이 흡수속도에 미치는 영향과 예측, 이를 통한 적절한 조작조건의 도출 가능성을 확인할 수 있었다.

• Asian-Australasian Journal of Animal Sciences
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• 제33권10호
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• pp.1656-1665
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• 2020

Objective: This study aimed to determine the effects of stress during slaughter of beef cattle on physiological parameters, carcass, and meat quality at a Federal Inspection Type slaughterhouse located in the southeast of Mexico. Methods: A total of 448 carcasses of male Zebu×European steers with an average age of 36 months were included. Carcass assessment of presence of bruises and bruise characteristics was carried out on each half-carcass. Blood variable indicators of stress (packed cell volume, neutrophil to lymphocyte ratio, glucose, cortisol concentration) and meat quality parameters (pH, color, shear force, drip loss) were evaluated. Results: Of the 448 carcasses evaluated, 81% of the carcasses showed at least one bruise; one bruise was detected in 36.6% and two bruises in 27.0% of animals. Of the 775 bruises found, 69.2% of the bruises were grade 1 in region 3. Of the 448 carcasses studied, 69.6% showed hyperglycemia (6.91 mmol/L); 44.3% and 22.7% showed high (74.7 ng/mL) and extremely high (108.8 ng/mL) cortisol levels, respectively, indicative of inadequate handling of animals during preslaughter and slaughter. Of the carcasses evaluated, 90.4% had a pH ≥5.8 with an average of pH 6.3. In both pH groups, meat samples showed L^⋆ values >37.0 (81.6%) and a shear force >54.3 N; meat pH≥5.8 group showed a drip loss of 2.5%. These findings were indicative of dark, firm, and dry (DFD) meat. According to principal component analysis, grades 1 and 2 bruises in region 3 and grade 1 bruises in region 5 were highly associated with cortisol, drip loss, and color parameters b^⋆ and h^⋆ and were negatively associated with L^⋆, a^⋆, and C^⋆. Conclusion: The bruises probably caused by stress-inducing situations triggered DFD meat. Appropriate changes in handling routines in operating conditions should be made to minimize stress to animals during the slaughter process to improve animal welfare and meat quality.

• 대한환경공학회지
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• 제28권8호
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• pp.860-865
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• 2006

비폭기 혐기상태에서 접촉 반응조내에서 임펠러의 종류와 운전조건에 따른 유동특성 및 SS의 효율적인 혼합은 오 폐수 반응조 전 공정효율에 직접적인 영향을 미치는 중요한 설계인자이다. 이를 위하여 본 연구에서는 수치해석적인 방법에 의하여 임펠러의 제원(형상및 크기)과 운전조건에 따른 반응조 내의 유동장과 SS농도분포를 계산하였다. 일차적으로 본 논문에서는 접촉 반응조 내부의 유동 및 농도를 수치 모사하여 임펠러 형상에 따른 전형적인 유동특성과 비교 검토함으로써 프로그램의 성능을 확인하였다. 또한 임펠러의 종류와 크기 그리고 위치 등에 따른 조직적인 변수연구를 수행함으로써 설계와 최적운전조건의 결정을 위한 임펠러 특성에 대한 유용한 자료를 도출하고자 하였다. 그 결과 임펠러 타입이 pitched-type 인 경우 flat-type에 비해 혼합 효율이 크게 향상됨을 알 수 있었으며 임펠러의 크기가 클수록, 다단으로 설치할수록 효율적인 혼합이 이루어짐을 확인하였다.

• 상하수도학회지
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• 제20권4호
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• pp.595-604
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• 2006

The growth characteristics of Commercially Developed Nitrifying Bacteria (CDNB) were studied in laboratoryscale. CDNB, a pure, artificially isolated bacterium, was cultivated to produce Cultivated Nitrifying Bacterium Group (CNBG). The average ammonia removal rate of CDNB was 0.0234g $NH_4^+-N/g$ MLSS/hr. CNBG was produced in the batch reactor and Specific Nitrification Rate (SNR) was determined at 0.0107g $NH_4^+-N/g$ MLSS/hr. The SNR of CNBG was lower than the SNR of CDNB because the diverse and multi-cultured microbial growth took place during cultivation. The effect of the temperatures and the mixing ratios of sewage and culture solution on the SNR of CNBG was studied. The SNR of CNBG, 0.0107g $NH_4^+-N/g$ MLSS/hr at $27^{\circ}C$, decreased to 0.0048g $NH_4^+-N/g$ MLSS/hr at $15^{\circ}C$, and temperature coefficient (${\Theta}$) was calculated to be 1.07. With the varied sewage mixing ratios, the SNR of CNBG remained unchanged. Activated sludge reactors maintaining an MLSS of 2,000mg/L at HRT of 4 h were operated under conditions in which dosage of Concentrated CNBG Solution (CCNBGS, 10,000mg MLSS/L) and application method of CNBG were varied. The reactor with 20mL of CCNBGS took shorter time to oxidize $NH_4^+-N$ reaching 1mg/L than the reactor with 5mL of CCNBGS showing that higher dosages were associated with greater mass removal of $NH_4^+-N$. However, the total removal was not great. In terms of different methods of CNBG application, reactor seeded with 20mL of CCNBGS took 3days to reach 1mg/L of effluent ammonia concentration while reactor dosed with 20% (v/v) CNBG implanted media took 2days. Both the control reactor and the reactor dosed with 20% (v/v) media only did not reach 1mg $NH_4^+-N/L$ after operating 18days. The reactor with CNBG implanted media had the highest $NH_4^+-N$ removal rate because of maintaining high concentration of Nitrifying Oxidizing Bacteria (NOM), and is regarded as an appropriate method for the activated sludge process.