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생산천이분석을 이용한 Eagle Ford 셰일 저류층의 다단계 수압파쇄설계 개선 연구
이형석 한국해양대학교 대학원 2018 국내석사
Multi-stage hydraulic fracturing has become common and proved technology to develop tight reservoirs such as shale for commercial production. Since production performance for shale reservoir highly depends on applied hydraulic fracture design, it remains a continuous challenge for the industry for improvement. In this study, rate transition analysis has been performed to estimate fracture geometry for various fracture design with different fluid selection in order to gain insight into their effect on production performance in U.S. Eagle Ford shale. The uncertainties on both reservoir properties and fracture distributions have been quantified by the probabilistic rate transient analysis using Monte-Calro simulation. Through the studies, the guidance on fracturing design has been derived by analyzing the relationship with fracture geometry growth with each design application based on Multi-stage hydraulic fracturing has become common and proved technology to develop tight reservoirs such as shale for commercial production. Since production performance for shale reservoir highly depends on applied hydraulic fracture design, it remains a continuous challenge for the industry for improvement. In this study, rate transition analysis has been performed to estimate fracture geometry for various fracture design with different fluid selection in order to gain insight into their effect on production performance in U.S. Eagle Ford shale. The uncertainties on both reservoir properties and fracture distributions have been quantified by the probabilistic rate transient analysis using Monte-Calro simulation. Through the studies, the guidance on fracturing design has been derived by analyzing the relationship with fracture geometry growth with each design application based on
소비자 특성과 구매성향이 브랜드 선택에 미치는 영향에 관한 연구
Today's retail market has experienced a lot of changes caused by various factors. Consumers show reasonable, practical, and value-oriented purchase behavior and purchase plans for items at a cheaper price have increased. The changes in consumer's purchase behavior made distributors develop their own brands to stimulate consumer purchasing decisions. This study attempts to examine the state of competition between national brands and private brands in facial tissues and explore what kinds of demographics and marketing variables have influence on the consumer purchase decision process. The private brands that used to have competitive edge in only prices have developed items similar to national brands in quality. With regard to the current market trends, studies on private brands have been conducted, but the studies are limited in dealing with factors that explain consumer purchase decision by focusing on the aspects of supply and only few domestic studies related to the market have been conducted. In addition, since most studies use a form of questionnaire to understand purchase intention, no studies of consumer decision making that apply practical purchase materials have been conducted. Therefore, this study analyzed the possibility of choosing brands at the point of the purchase and the factors that affect the purchase by reconstructing panel materials that include purchase records for each individual and adopting a discrete choice model that better estimate a subordinate variable, brand choice. In order to conduct a positive research, the appropriateness of research models were examined based on the samples collected for analyses and the factors that have influence on consumer purchase patterns and purchase types were explored by a multinomial logit model. The results of the study are as follows. First, certain changes in prices had no effect in making high-income consumers switch brands. The survey showed that older consumers were more likely to purchase famous brands. Furthermore, higher?]income consumers were less likely to be sensitive to prices and purchase lower price items. Second, the place of purchase is a critical factor in choosing brands. Consumers choose distributor's brands rather than famous brands at department stores or discounters. It reflects that even high-income consumers are not sensitive to brand values since they have a high level of trust in items at large department stores or discounters. Third, the results from the analysis on consumer responses toward sale promotion are as follows. High-income consumers were less likely to purchase sales promotion items. It showed that high-income consumers were not sensitive to price changes and it seemed that they recognized themselves as differentiated classes. Fourth, in the results of the analysis on each point of purchase, consumer characteristics that show a sense of loyalty are as follows. Consumers who prefer to major brands recognize high prices reflect brand values and they seem to prefer to major brands. However, as the purchase frequency increased, the number they purchased famous brands decreased. Since low involvement products such as tissue papers had low brand recognition, the price competition from discount brands changed consumer purchase attitudes by discount prices as the purchase frequency increased. Finally, consumers who constantly purchase distributor's brands are strongly influenced by sales promotion through discount. They are only concerned about the prices of products and they are categorized as a consumer group sensitive to price fluctuations. Based on a variety of results, this study tried to perceive precise consumer purchase behavior more correctly than previous studies that depended on subjective responses by using real purchase data and panel materials that include demographic data and attempted to redefine the market share in low involvement products that distributors take to, traditional manufacturers' responses and the changes in markets caused those factors from a consumer's point of view. With regard to such aspects, this study made an every effort to provide suggestions to apply appropriate marketing strategies by analyzing patterns for each consumer and consumer preferences and since this study can be applied to facial tissues as well as other low involvement products, it is predicted that this study provides meaningful academic experiences as a basic model that can be applied to other researches in brand choices. Regardless of the results, this study is limited by several factors seen below. First, this study classified brands into three categories; famous brands, mid-ranged brands, and distributor's brands and analysis was conducted by limiting the frequency of purchase to 3 times. In order to better understand consumer attitudes, the frequency of purchase should increase. Second, as the changes in consumer purchase decisions could happen during the frequent purchase activities, this study failed to conduct such analysis due to the limitation of materials and a lack of methodology. The study can allow enterprises to establish marketing strategies to prevent consumers from brand changes by examining the time when consumers change brands. Finally, efforts to make distributors recognize brands as well as analyze manufactures' brands and distributors' brands should be made or the effects of distributor's brand images on the sales of own products should be explored for more advanced studies.
나노크기 결정성 BaTiO₃ 분말의 제조 및 특성 평가
60~100 ℃의 반응온도에서 TiOCl_(2) 수용액과 BaCl_(2)·2H_(2)O 수용액의 혼합용액을 강알칼리 수용액에 첨가하여 결정성 BaTiO_(3) 분말을 합성하였다. 반응온도와 시간, 용액 pH, 반응물 농도와 같은 반응 변수들이 입자의 크기와 형태에 미치는 영향을 조사하였다. 결정성 BaTiO_(3) 입자가 생성되기 위한 반응용액의 최소 pH 는 약 13.0 이상이었으며, 동일 pH 조건에서 반응물의 농도가 증가 할수록 균일한 형태의 구형 입자들이 형성되었다. 특히, 1.5 M 의 KOH (pH=13.6) 용액에서 80 ℃에서 12 시간 동안 반응시켜 약 80~90 ㎡/g 의 비표면적을 가지는 70 nm 이하의 입방정계 BaTiO_(3) 입자의 제조가 가능하였다. 저온 침전반응에서 BaTiO_(3) 의 입자 형성 메커니즘을 연구하였다. 본 연구에서 Partial Charge Model 로부터 다양한 pH 범위에서 TiOCl_(2) 와 BaCl_(2) 가 형성될 수 있는 화합물들을 예상하였고, pH 13 이상의 용액에서 용해된 [TiO(OH)_(4)]^(2-)이 Ba^(2+) 이온과 반응하여 형성된 무정형 [BaTiO(OH)_(4)]^(0) 가 80 ℃에서 숙성과정을 통해 BaTiO_(3) 입자가 형성되는 것을 확인하였다. 따라서 [TiO(OH)_(4)]^(2-) + Ba^(2+) → [BaTiO(OH)_(4)]^(0) → BaTiO_(3) + H_(2)O식이 적절한 화학반응으로서 제시되었다. Johnson-Mehl-Avrami 식으로 BaTiO_(3) 입자의 형성 메카니즘이 용해-침전반응으로 임을 확인할 수 있었다. 상대적으로 낮은 온도에서 BaTiO_(3) 입자의 빠른 핵생성과 결정화 과정이 진행된 것으로부터, 사용된 TiOCl_(2) 전구체가 BaTiO_(3) 입자의 핵생성과 결정화 과정에 영향을 미치는 것을 확인하였다. A low temperature precipitation reaction procedure for barium titanate has been developed. Crystalline BaTiO_(3) particles were synthesized from aqueous solution of TiOCl_(2) and BaCl_(2)·2H_(2)O in a strong alkaline solution at 60~100 by ℃ a precipitation process. The influence of reaction parameters such as reaction temperature and time, solution pH, and reactant concentration on the particle size and morphology from low-temperature aqueous solutions was investigated. The pH condition is found to be a critical reaction parameter such that production of phase pure BaTiO_(3) particles requires a highly alkaline condition (i.e., pH >13.0). As the reactant concentration in the strong alkaline solution (pH >13.0) increased, the smaller and more distinct spherical particles with narrow size distribution were formed. The well-defined spherical BaTiO_(3) particles having an average crystallite size of 70 nm with average specific surface area of 80~90 ㎡/g were successfully synthesized at 80 ℃ for 12 h in KOH solution of 1.5 M (pH=13.6). Particle formation mechanisms of BaTiO_(3) in this particular precipitation process are also investigated. We will predict the aqueous chemical reactions of TiOCl_(2) and BaCl_(2) complexes in the various pH ranges from the partial charge model (PCM), which was based on the electrical interactions between the partial electric, δ, carried by each atom and molecules. In the case of barium titanate particle formation, it is expected that amorphous [BaTiO(OH)_(4)]^(0), prior to the formation of BaTiO_(3) particles through aging at 80 ℃, forms in a strong alkaline solution (pH >13) by dissolution-precipitation process which the as-dissolved [TiO(OH)_(4)]^(2-) species react with Ba^(2+) in the solution under a saturated condition. [TiO(OH)_(4)]^(2-) + Ba^(2+) → [BaTiO(OH)_(4)]^(0) → BaTiO_(3) + H_(2)O is proposed as the relevant chemical reaction, in which the hydroxyl species (OH-) play a kinetically important role in nucleation and growth. The Johnson-Mehl-Avrami kinetic analysis corroborates microstructural evidence which indicates that the formation mechanism is dissolution-precipitation. Similar efforts are directed towards evaluating the influences of the Ti precursor characteristics on BaTiO_(3) particle formation mechanisms. The aqueous TiOCl_(2) solution significantly affects the reaction kinetics and particle characteristics of the synthesized BaTiO_(3), which eventually enhances nucleation and crystallization kinetics of BaTiO_(3) particles, even though at low temperature of 80 ℃.
This study is to reconsider characteristics and problems of the subjects of participation by analysizing the process of policy-making on reduction of teacher's retiring age. The decisive factors of educational policy include political, social and cultual environmental one that forms solution of specific educational problems, characteristic & appearance of policy system that directively produces an alternative from educational problems, educational policy related information & knowledge, human material resources, and formal organization & related group of policy system. Therefore, the decision of specific educational policy is a product of mutual dynamic process among each decisive factors centering around policy system, and it would be meaningful to look over what influence the subjects of participation have on the process of educational policy-making by analysizing mutual dynamic action among the subjects of participation taking part in the process of educational policy-making among these decisive factors. This study would lay stress on interaction of the sbjects of participation taking part in the process of educational policy-making and interrelationship of that process. For this, objects fixed are as follows. First, we would like to look for conceptional model by which we can explain and predict their relation among subjects of participation in the process of educational policy-making by looking over the participation model of educational policy-making process of the existing model of theory on its process. Second, we would like to grasp type & role of the subjects of participation related to the process, and interrelationship. Third, by looking over ways of resolution and problems on interaction among the subjects of participation, we would like to reconsider democratic degree and relationality of that process. For that, after looking at the model of policy decision proposed from various point of view and a theory on the process of educational policy-making through study on documents such as separate volumes of home & abroad, all sorts of theses , theses for a master's & doctor's degree, research papers and reference data carried in a separate volumes of home & abroad and all sorts of theses centering around cases of adjusting policy of teacher's retiring age, we will analysize role of the subjects of participation in the process of educational policy-making with establishment of conceptional frame by which we can explain and analysize the process of educational policy-making. The results from analysis of the subjects of participation in the proess of our educational policy-making are as follows. First, interrelationship among the subjects of participation in that process is composed of patterns of action such as directions(order), demand, claim, report, resources offered, advice and public opinion. Considering from the view point of the Ministry of Education, these patterns of interaction seem to provoke relations of conflict ; 'request verse request', 'request verse claim' and 'claim verse claim'. These are patterns of relation among subjects of participation causing relation of conflict in the process of educational policy-making, and on the other hand, relation of 'request verse request' is apt to occur in case that request of the Ministry of Education and one of the other Ministry are opposed to each other, relation of 'request verse claim' in case that request of the Ministry of Education and claim of a profit body are opposed to each other, and relation of 'claim verse claim' occurs in aspects of conflict among profit bodies. Second, it seems that relation of conflict showing among the subjects of participation in process of educational policy-making is ascribed to (1) difference of policy goal, (2) difference of acknowledgment on the actual of policy, (3) mutual distrust on decision of policy, and (4) authoritative type of decision of policy makers. As plans to solve this relation of conflict, (1)method of solution to concentrate upon a new alternative, (2)persuasion to try out connection with upper aims seeking for direct aims, negotiation in which contradiction of acknowledgment, threatening & disguise are put in practice, and (3)method of politics in which coalition to rally powers is used without limiting to the subjects of participation are recommended, and referring to rational solution of relation of conflict in the process of educational policy-making, an analytical method of solution like settlement of problems or persuasion rather than method of non-analytical solution like one of negotiation or politics seems to be more desirable. And relation of conflict among the subjects of participation in the process of educational policy-making would be meaningful in that point in which effect of policy to make up innovation of furture-oriented policy of education appears. As showed above, analysis on the subjects of participation in the process of educational policy-making will contribute to grope of the process of more rational & democratic educational policy-making by disclosing more dynamic process, its characteristic and related problems among each various subjects of participation acting concerning educational policy-making.
DEA 모형을 이용한 우리나라 해운업체의 상대적 효율성 분석
The role of shipping industry is very important in Korean economy. However, few studies have focused on the efficiency of shipping companies. The purpose of this paper is to measure and analyze the relative efficiency of Korean shipping companies using Data Envelopment Analysis(DEA). We use CCR-O and BCC-O models to evaluate the efficiency, return to scale, and reference set of 50 shipping companies in 2004. We apply DEA/Window model to 12 shipping companies for the analysis of the trend and stability of the efficiency over 10 years(1995-2004).
승촌보 개방에 따른 영산강 수위강하가 상류 농경지 지하수 이용에 미치는 영향
수생태계의 자연성 회복과 수질 개선을 목적으로 2017년 11월 4대강의 보 수문을 개방하였다. 하지만 이로인해 승촌보 상류지역 일부 농경지에서 지하수 이용 장애로 인한 농작물 피해가 발생하였다. 본 연구에서는 승촌보 인근 농경지 지하수 장애발생 우려지역에 대한 정밀 시추조사 및 Visual MODFLOW 프로그램을 이용한 지하수 모델링을 이용해 지하수 영향을 정량적으로 평가하고, 연구지역의 지하수 이용 장애의 원인을 평가하고 이를 해결하기 위한 전략을 논의하였다. 표준관입시험을 통해 획득된 시료의 일부를 대상으로 입도분석을 실시하여 충적층의 물리적 특성을 파악하고 양수시험을 통해 투수량계수와 수리전도도를 구하여 모델에 적용하였다. 연구지역의 대수층 수리상수 자료와 지질․지형 및 수문 자료를 종합하여 지하수 흐름계를 최대한 단순화시킨 개념 모델을 설계하였다. 모델 영역에 대한 3차원 격자망을 설정하였고, 모델 영역 내 충적층의 분포, 강, 지류하천, 유역 경계 등을 고려하여 경계조건 설정하였다. 정류 모델은 연구지역에서 측정된 지하수위 자료를 이용하였고, 함양량은 해당지역 지하수 기초조사의 분석 결과를 인용하여 모델에 반영하였다. 모델 보정을 위해 연구지역의 양수량을 모델 변수로 이용하여 보정을 실시하였으며, 부정류모델에서는 양수시나리오를 조절하며 보정을 하였다. 보정된 모델을 이용하여 물수지 분석을 실시하였고 보 개방 시 지하수를 많이 이용하는 지역을 중심으로 지하수위가 크게 하강하면서 모델의 상부층 일부 지역이 Dry cell로 바뀌는 것으로 모사되었다. 이러한 점으로 미루어봤을 때 지상펌프를 사용하는 일부 미나리 재배 일대에 지하수위가 급격히 하강하면서, 제약수위보다 수위가 떨어져 양수를 할 수 없게 되어 지하수 이용 장애가 발생하는 것으로 분석되었다. In November, 2017, the water gates of the weir were opened to improve the water quality of the four main rivers and to restore the naturalness of the water ecosystem. However, this resulted in damage to crops due to reduced groundwater withdrawal or disability at some agricultural sites in the seungchon weir upstream areas of the sub-communities. The purpose of this study is to quantitatively evaluate groundwater impacts using groundwater modeling using a precise drilling investigation and a visual MODFLOW program for the areas where the groundwater disturbance is likely to occur in farming villages near the village, the strategy was discussed. The physical characteristics of the alluvial deposits were analyzed by particle size analysis of some of the samples obtained through the standard penetration test, and the permeability coefficient and hydraulic conductivity were obtained through the pumping test and applied to the model. A conceptual model was designed as maximum simple as posible the groundwater flow system by integrating topographic, geological and hydrological data and aquifer constants data from the study area. A 3D grid network was established for the model area, and boundary conditions were set considering the distribution of alluvial deposits in the model area, river, tributary stream, and watershed boundary. The steady-state model used the groundwater lvel data measured in the study area and the recharge amount was reflected in the model by citing the analysis results of the groundwater baseline survey in the area. In order to calibrate the model, the calibration was performed using the pumping capacity of the study area as the model parameter. In the unsteady-state model, the pumping scenario was adjusted and calibrated. The zone budget analysis using the calibrated model was carried out and as gate opening of the weir, the groundwater level dropped significantly around the area where the groundwater was heavily used, some parts of the upper part of the model were converted into dry cells. From this point of view, the groundwater level drops sharply in some water parsley cultivation areas using ground pumps, It is analyzed that groundwater use obstacle occurs because the water level is lower than the water level of the restriction(PAT).