• International Journal of Automotive Technology
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• 제4권3호
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• pp.125-133
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• 2003

Several models for the evaluation of Gross Heat Release from the internel combustion engine (ICE) are often used in literature. One of these is the First Law - Single Zone Model (FL-SZM), derived from the First Law of Thermodynamic. This model present a twice advantage: first it describes with accuracy the physic of the phenomenon (charge heat release during the combustion stroke and heat exchange between gas and cylinder wall); second it hat a great simplicity in the mathematical formulation. The evaluation of Heat Release with the FL-SZM is based on pressure experimental measurements inside the cylinder, and ell the assumption of several parameters as the specific heat ratio, wall temperature, polytropic exponent for the motored cycle evaluation, and many others. In this paper the influence of gases thermodynamic properties on Cross Heat Release has been esteemed. In particular the influence of an appropriate equation for k=k(T) (specific heat ratio vs. temperature) which describes the variations of gases thermodynamic properties with the mean temperature inside the cylinder has been evaluated. This equation has been calculated by new V order Logarithmic Polynomials (VoLP), fitting experimental gases properties through the least square methods.

• 한국항해항만학회:학술대회논문집
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• 한국항해항만학회 1999년도 추계학술대회논문집
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• pp.253-261
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• 1999

It is essential for port planning, coastal zone management and environmental impact study to analyze the variation of current and water quality due to the development of water area and discharged water from the estuary barrage and basin, etc. Mokpo sea area has downstream from a long river and two large basins, the Yongsan river and Yongam-Kumho basins, discharging much of water through water gates for the purpose of flood and prohibition of salt intrusion to the inland fresh water area. In this study, the numerical calculation were carried out for the analysis of diffusion characteristics due to discharging operation, adopting the results of tidal current simulation. ADI method is applied to the governing equation for the movement of sea water and diffusion and 6-point method to the advection terms of diffusion equation. As the results of this study, it is known that the discharging operation causes increasing and/or decreasing of current velocity and enlarging and/or depressing of pollutant diffusion limits depending on the distance from the discharging gates and the modes of discharging operation. To utilize these result, the linked gate operation and the method increasing exchange of sea water must be considered.

• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2012년도 학술발표회
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• pp.35-35
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• 2012

Most grid-based distributed hydrologic models are complex in terms of data requirements, parameter estimation and computational demand. To address these issues, a simple grid-based hydrologic model is developed in a geographic information system (GIS) environment using storage-release concept. The model is named GIS Storage Release Model (GIS-StoRM). The storage-release concept uses the travel time within each cell to compute howmuch water is stored or released to the watershed outlet at each time step. The travel time within each cell is computed by combining the kinematic wave equation with Manning's equation. The input to GIS-StoRM includes geospatial datasets such as radar rainfall data (NEXRAD), land use and digital elevation model (DEM). The structural framework for GIS-StoRM is developed by exploiting geographic features in GIS as hydrologic modeling objects, which store and process geospatial and temporal information for hydrologic modeling. Hydrologic modeling objects developed in this study handle time series, raster and vector data within GIS to: (i) exchange input-output between modeling objects, (ii) extract parameters from GIS data; and (iii) simulate hydrologic processes. Conceptual and structural framework of GIS StoRM including its application to Pleasant Creek watershed in Indiana will be presented.

• 대한기계학회논문집B
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• 제25권3호
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• pp.422-432
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• 2001

An analytical characterization is presented on the transient heat transfer by an oscillating flow through a porous slab. Based on a two-equation model, analytic solutions are obtained for both the fluid and solid temperature variations. Two parameters are identified as the Stanton number for the internal heat exchange and the ratio of the thermal capacities between the solid and fluid phases. The heat transfer characteristics are shown to be classified into four regimes according to the two parameters and physical interpretation is presented on the particular heat transfer processes within each regime. In addition, the condition for the local thermal equilibrium between the phases is examined and the relevant criterion is suggested.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2006년도 하계학술발표대회 논문집
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• pp.953-958
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• 2006

Perimeter zone has been reinforced by active systems, such as fan-coil units, because it causes an increase in heating and cooling loads, dew condensation in winter, or discomfort with cold-draft to residents in buildings, through poor insulation by light-weighed skin due to progressing multi-storied buildings and skyscrapers. However, because these active systems raise Its capacity so that fossil fuel is used as much as they are added, and ultimately, greenhouse effect is urged, we proposed BIPV system functioned as solar collector which can substitute active system. As an early stage, heat balance equation in steady-state by Fortran was used not only for pre-heating effect and electric power capacity during the day in winter, but also for electric power capacity during day in slimmer and sky radiation effect during night in summer. Especially, we should have considered shading on PV, since even a little bit of it makes the efficiency too low for the PV to work. Still, when the flux of pre-heated air was increased to make air-barrier, its temperature was not enough to make it because the speed of heat exchange was too fast to warm up the air, thus the capacity to meet the condition was evaluated, and electric power from PV was made used for it.

• 한국광물학회지
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• 제29권2호
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• pp.59-71
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• 2016

방사성 폐기물의 주요 성분 중 하나인 Cs의 자연에서 정출되는 제올라이트인 차바자이트(chabazite)에 대한 흡착 특성을 알아보기 위해 XRD, EPMA, EC, pH, ICP 분석방법을 이용하여 동정 및 화학성분 분석을 하였다. 그리고 추가적으로 양이온 교환능력을 확인하였고 시간과 농도에 따른 Cs 흡착 및 타 양이온($Li^+$, $Na^+$, $K^+$, $Rb^+$, $Sr^{2+}$)에 대한 경쟁흡착 실험을 실시하였다. 본 연구에 사용된 차바자이트의 화학식은 $Ca_{1.15}Na_{0.99}K_{1.20}Mg_{0.01}Ba_{0.16}Al_{4.79}Si_{7.21}O_{24}$였고 Si/Al 비율과 양이온 교환능력은 각각 1.50와 238.1 meq/100 g으로 측정되었다. 시간과 농도에 따른 Cs 흡착 등온 실험결과를 흡착 반응 속도 모델과 등온 흡착 모델에 적용해본 결과 각각 유사 2차 반응과 Freundlich 모델에 부합하였으므로 고체 표면에 흡착 물질이 2개 이상의 다중 흡착 층을 이루는 것을 알 수 있으며 모델로부터 유도되는 상수 값을 통해 차바자이트의 Cs 흡착 능력정도를 평가하였다. 경쟁 흡착 실험 결과 이온의 종류에 따라 이온 교환되어 차바자이트 내에 존재하는 Cs의 몰 분율에서 차이를 보였다. 각 양이온과 세슘과의 액체에서 고체 내로 흡착되는 경쟁 경향이 $Na^+$, $Li^+$, $Sr^{2+}$, $K^+$ 그리고 $Rb^+$ 순으로 선택성이 있었으며 이는 수화 직경의 순서와 유사한 양상을 보였다. Kielland 도시법을 이용하여 Cs과 타 양이온의 교환 평형관계를 도시해 보았을 때에는 $Sr^{2+}$가 가장 선택성이 높았으며 그 다음으로 $Na^+$, $Li^+$, $K^+$, $Rb^+$ 순으로 선택성이 나타났고 모든 타 양이온에 대하여 양의 값을 나타내었다. Kielland 도시법에서 나타나는 평형상수 값의 순서는 열역학 및 반응 속도론적인 의미를 내포하고 있으므로 수용액에서 공극 내로 들어가는 Cs은 $Sr^{2+}$과의 공존 시 선호도가 높다는 것을 알 수 있다. 이는 경쟁하고 있는 수화된 양이온 간의 직경 차이가 원인일 것으로 추측된다. 본 연구 결과는 차바자이트가 높은 Cs 친화력을 가지는 것을 보여줌으로써 방사성 물질로 오염된 물에서 Cs을 선택적으로 교환할 수 있음을 보여주고 있다.

• 대한환경공학회지
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• 제28권5호
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• pp.549-557
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• 2006

화력발전소에서 발생하는 폐 음이온교환수지를 분해하기 위해 초임계수 산화 특성 연구를 진행하였다. 폐수지는 음이온교환수지와 양이온교환수지가 혼합된 상태로 배출되었으며, 혼합된 폐수지에서 고-액 유동층을 이용하여 음이온수지를 분리하였다. 분리된 음이온 수지는 원소분석과 열분석을 통해 양이온 수지가 혼합되지 않았음을 확인하였다. 음이온수지를 고압 펌프를 이용하여 초임계수 산화 반응 장치에 연속적으로 주입하기 위해 습식 ball mill을 이용하여 분쇄, 슬러리로 제조하였다. 압력 25.0 MP콘 체류시간 2분, 반응 온도 $500^{\circ}C$에서 처리수의 COD는 99.9%이상 분해됨을 확인하였지만, 총 질소 분해율은 41% 정도로 나타났으며, 슬러리에 질산을 혼합하면 처리수의 총 질소가 감소하였다. 처리수의 COD와 총 질소(T-N) 함량을 목적변수로 설정하여 음이온 수지 슬러리를 분해하는 최적 조건을 도출하기 위해 통계적 실험계획법인 중심합성계획법을 적용하였다. 처리수의 COD는 반응 온도 $500{\sim}540^{\circ}C$, 압력 25.0 MPa, 반응기 체류시간 2분 조건에서 $99.9{\sim}100%$까지 충분히 분해되었으며, 온도 변화와 질산 주입량 변화에 영향을 받지 않았다. 그러나 처리수의 총 질소는 질산 주입량의 변화에 대한 영향이 큰 것으로 확인되었다. 처리수의 총 질소는 회귀분석을 통해 질산 주입량의 함수로 나타낼 수 있었으며, 결정계수($r^2$)는 95.8%로 계산되었다.

• 경영과정보연구
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• 제39권2호
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• pp.77-94
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• 2020

국가경제 차원에서 서비스산업의 비중과 중요성이 높아지고 있음에 반해 항공서비스산업 종사자인 객실 승무원의 근속율과 업무 만족도는 높지 않다. 이에 본 연구는 이른바 감정노동에 종사하는 객실승무원을 대상으로 그들이 직무환경에서 경험하는 직무스트레스를 감소시킬 수 있는 주요요인이 무엇인지, 그리고 직무스트레스가 객실승무원 구성원의 성과와 태도에 어떠한 영향을 미치는 지를 파악하고자 한다. 구체적으로 본 연구는 객실승무원의 긍정적인 심리상태가 승무원 구성원들 간 상호작용 및 승무원 개인의 직무스트레스에 어떠한 영향을 미치는지, 나아가 궁극적인 성과측면에서 구성원의 조직몰입과 지식공유에 미치는 어떠한 영향을 미치는 지를 검증하고자 한다. 이러한 상호작용 관계에서 고려되는 주요 구성개념은 승무원의 긍정심리자본과 리더-구성원 교환관계(LMX), 직무스트레스, 조직몰입, 지식공유의 5가지 요소이다. 본 연구는 국내 항공사 객실승무원에게 설문조사하여 최종 390부를 대상으로 SPSS/PC version 20.0의 통계 프로그램 및 AMOS 20.0을 사용하여 분석하였다. 연구 결과, 승무원 구성원들 간 우호적인 리더-구성원 교환관계(LMX)는 직무스트레스를 낮추는 데에 유의한 역할을 하며, 직무스트레스가 낮을수록 구성원 성과인 조직몰입과 지식공유에 긍정적인 영향을 미치는 것이 확인되었다. 무엇보다도 본 연구에서는 구성원의 긍정심리자본은 다른 요인들에 영향을 미치는 트리거 역할을 함을 검증할 수 있었다. 따라서 본 연구는, 항공사들이 경쟁력 있는 인적자원 확보를 위해 승무원 개인이 긍정적인 심리상태를 유지하는데 중점을 두어야하며 이를 위한 조직차원의 제도개선 및 환경개선이 필요함을 시사하고 있다.

• 유통과학연구
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• 제10권2호
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• pp.7-17
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• 2012

The aim of this study is to empirically explore micro and macroeconomic factors affecting the Pakistani sugar industries and searching the energy potential of this industry, through the survey of literature. The empirical part has been explored by employing Vector Autoregression (VAR), Granger Causality tests and simultaneous equation models through quarterly data for the period of 1991q2-2008q4. The study also aims to devise policies for the development of sugar industries and identify its growing importance for the energy sector of Pakistan. Empirical tests applied on the domestic prices of sugar, domestic interest rates, and exchange rate, productive capacities of sugar mills, per capita income, world sugar prices on cultivable area and sugar production reveal very useful results. Results reveal an improvement of productive capacity of the sugar mills of Pakistan on account of increasing crushing capacity of this sector. Negative effect of rising wholesale prices on the harvesting area was also observed. Profit earnings of the sugar mills significantly increase with the rise of sugar prices but the system does not exist for the farming community to share the rising prices of sugar. The models indicate positive and significant effect of local prices of sugar on its volume of import. Another of the findings of this study positively relates the local sugar markets with the international prices of sugar. Additionally, the causality tests results reveal exchange rate, harvesting area and overall output of sugarcane to have significant effects on the local prices of sugar. Similarly, import of sugar, interest rate, per capita consumption of sugar, per capita national income and the international prices of sugar also significantly affect currency exchange rate of Pakistani rupee in terms of US$. The study also finds sugar as an essential and basic necessity of the Pakistani consumers. That is why there are no significant income and price effects on the per capita consumption of sugar in Pakistan. All the empirical methods reiterate the relationship of variables. Economic policy makers are recommended to improve governance and management in the production, stock taking, internal and external trading and distribution of sugar in Pakistan using bumper crop policies. Macroeconomic variables such as interest rate, exchange rate per capita income and consumption are closely connected with the production and distribution of sugar in Pakistan. The cartelized role of the sugar industries should also be examined by further studies. There is need to further explore sugar sector of Pakistan with the perspective of energy generation through this sector; cartelized sugar markets in Pakistan and many more other dimensions of this sector. Exact appraisal of sugar industries for energy generation can be done appropriately by the experts from applied sciences.

• 유통과학연구
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• 제14권6호
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• pp.53-63
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• 2016

Purpose - This study examines the effects of the influence strategies on sales representative and headquarter trust, and investigates how sales representative trust plays a mediating role in the relationship between influence strategies and headquarter trust. For these purposes, a structural model which consists of several constructs was developed. In this model, influence strategies that consist of relational influence strategies (information exchange, recommend, promise) and mandatory influence strategies (legal plea, request, threat) were proposed to affect the sales representative trust and in turn, increase the headquarter trust. Thus, this study proposed that sale representative trust plays a core mediating role in the relationship between relational and mandatory influence strategies and headquarter trust in B2B food materials distribution context. Research design, data, and methodology - For these purposes, the authors collected the data from 208 B2B specialized complex agents. We used the 2,200 B2B specialized complex agents which trade with CJ, Ottogi, and Daesang firms and supply food materials to restaurant, school cafeteria, supermarket and traditional market as a sample frame. Once we identified 330 B2B specialized complex agent owners, CEOs, and/or Directors who had agreed to participate in this study, we dropped off a questionnaire at each B2B specialized complex agent and explained the purpose of this study. The survey was conducted from October 1, 2015 to December 15, 2015. A total of 230 questionnaires were collected. Of these collected questionnaires, 28 questionnaires excluded since they had not been fully completed. The data were analyzed using frequency test, reliability test, measurement model analysis, and structural equation modeling with SPSS and SmartPLS 2. Results - First, information exchange, recommendation, and promise of relational influence strategies had positive effects on sales representative trust. The threat of mandatory influence strategies had a negative effect on sales representative trust, but legal plea and request did not have a significant effect on sales representative trust. Second, information exchange and recommendation of relational influence strategies had positive effects on headquarter trust, but promise did not. Also, legal plea, request, and threat of mandatory influence strategies did not have a significant effect on headquarter trust. Third, this findings show that sales representative trust plays a partial mediator between information exchange and headquarter trust, and threat and headquarter trust, and a full mediator between promise and headquarter trust, and recommendation and headquarter trust. Conclusions - The aim of this study was to examine the effects how diverse dimensions of relational and mandatory influence strategies relate to sales representative trust and headquarter trust. To do so, we integrated the influence strategies and the trust transfer theory to hypothesize that various influence strategies increase sales representative and headquarter trust. The findings of this study suggest that headquarter firms should establish and enforce proper influence strategies guidelines to make clear what proper actions sales representatives should implement in relationship with B2B specialized complex agents. Also, relational and mandatory influence strategies must be regarded as a long-term and ongoing strategy that eventually build a long-term orientation with B2B specialized complex agents and guarantee a company's sustainable growth and success.