• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.14 no.12
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• pp.1102-1139
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• 2002

A review on the papers published in the Korean Journal of Air-Conditioning and Refrigerating Engineering in 2000 and 2001 has been done. Focus has been put on current status of research in the aspect of heating, cooling, ventilation, sanitation and building environment. The conclusions are as follows. (1) Most of fundamental studies on fluid flow were related with heat transportation of facilities. Drop formation and rivulet flow on solid surfaces were interesting topics related with condensation augmentation. Research on micro environment considering flow, heat, humidity was also interesting for comfortable living environment. It can be extended considering biological aspects. Development of fans and blowers of high performance and low noise were continuing topics. Well developed CFD technologies were widely applied for developing facilities and their systems. (2) Most of papers related with heat transfer analysis and heat exchanger shows dealt with convection, evaporation, and channel flow for the design application of heat exchanger. The numerical heat transfer simulation studies have been peformed and reported to show heat transfer characteristics. Experimental as well as numerical studies on heat exchanger were reported, while not many papers are available for the system analysis including heat exchanger. (3) A review of the recent studies on heat pump system shows that performance analysis and control of heat pump have been peformed by various simulations and experiments. The research papers on multi-type heat pump system increased significantly. The studies on heat pipe have been examined experimently for change of working characteristics and strut lure. Research on the phase change has been carried out steadily and operation strategies of encapsulated ice storage tank are reported experimentally in several papers. (4) A review of recent studies on refrigeration/air conditioning system have focused on the system performance and efficiency for new alternative refrigerants. Evaporation and condensation heat transfer characteristics are investigated for tube shapes and new alternative refrigerants. Studies on components of refrigeration/air conditioning system are carried to examine efficiency for various compressors and performance of new expansion devices. In addition to thermophysical properties of refrigerant mixtures, studies on new refrigerants are also carried out, however research works on two-phase flow seemed to be insufficient. (5) A review of the recent studies on absorption cooling system indicates that heat and mass transfer phenomena have been investigated to improve absorber performance. Various experimental data have been presented and several simulation models have been proposed. A review of the recent studies on duct and ventilation shows that ventilation indices have been proposed to quantify the ventilation performance in buildings and tunnels. Main efforts have been focused on the applications of ventilation effectiveness in practice, either numerically using computational fluid dynamics or experimentally using tracer gas techniques. (6) Based on a review of recent studies on indoor thermal environment and building service systems, research issues have mainly focused on many innovative ideas such as underfloor air-conditioning system, personal environmental modules, radiant floor cooling and etc. Also, the new approaches for minimizing energy consumption as well as improving indoor environmental conditions through predictive control of HVAC systems, various activities of building energy management and cost-benefit analysis for economic evaluation were highlighted.

• Journal of Intelligence and Information Systems
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• v.23 no.2
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• pp.39-70
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• 2017

Data-drive analytics techniques have been recently applied to public surveys. Instead of simply gathering survey results or expert opinions to research the preference for a recently launched product, enterprises need a way to collect and analyze various types of online data and then accurately figure out customer preferences. In the main concept of existing data-based survey methods, the sentiment lexicon for a particular domain is first constructed by domain experts who usually judge the positive, neutral, or negative meanings of the frequently used words from the collected text documents. In order to research the preference for a particular product, the existing approach collects (1) review posts, which are related to the product, from several product review web sites; (2) extracts sentences (or phrases) in the collection after the pre-processing step such as stemming and removal of stop words is performed; (3) classifies the polarity (either positive or negative sense) of each sentence (or phrase) based on the sentiment lexicon; and (4) estimates the positive and negative ratios of the product by dividing the total numbers of the positive and negative sentences (or phrases) by the total number of the sentences (or phrases) in the collection. Furthermore, the existing approach automatically finds important sentences (or phrases) including the positive and negative meaning to/against the product. As a motivated example, given a product like Sonata made by Hyundai Motors, customers often want to see the summary note including what positive points are in the 'car design' aspect as well as what negative points are in thesame aspect. They also want to gain more useful information regarding other aspects such as 'car quality', 'car performance', and 'car service.' Such an information will enable customers to make good choice when they attempt to purchase brand-new vehicles. In addition, automobile makers will be able to figure out the preference and positive/negative points for new models on market. In the near future, the weak points of the models will be improved by the sentiment analysis. For this, the existing approach computes the sentiment score of each sentence (or phrase) and then selects top-k sentences (or phrases) with the highest positive and negative scores. However, the existing approach has several shortcomings and is limited to apply to real applications. The main disadvantages of the existing approach is as follows: (1) The main aspects (e.g., car design, quality, performance, and service) to a product (e.g., Hyundai Sonata) are not considered. Through the sentiment analysis without considering aspects, as a result, the summary note including the positive and negative ratios of the product and top-k sentences (or phrases) with the highest sentiment scores in the entire corpus is just reported to customers and car makers. This approach is not enough and main aspects of the target product need to be considered in the sentiment analysis. (2) In general, since the same word has different meanings across different domains, the sentiment lexicon which is proper to each domain needs to be constructed. The efficient way to construct the sentiment lexicon per domain is required because the sentiment lexicon construction is labor intensive and time consuming. To address the above problems, in this article, we propose a novel product reputation mining algorithm that (1) extracts topics hidden in review documents written by customers; (2) mines main aspects based on the extracted topics; (3) measures the positive and negative ratios of the product using the aspects; and (4) presents the digest in which a few important sentences with the positive and negative meanings are listed in each aspect. Unlike the existing approach, using hidden topics makes experts construct the sentimental lexicon easily and quickly. Furthermore, reinforcing topic semantics, we can improve the accuracy of the product reputation mining algorithms more largely than that of the existing approach. In the experiments, we collected large review documents to the domestic vehicles such as K5, SM5, and Avante; measured the positive and negative ratios of the three cars; showed top-k positive and negative summaries per aspect; and conducted statistical analysis. Our experimental results clearly show the effectiveness of the proposed method, compared with the existing method.

• Journal of Intelligence and Information Systems
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• v.17 no.4
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• pp.255-277
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• 2011

Product Service System(PSS), which is an integrated combination of product and service, provides new value to customer and makes companies sustainable as well. The objective of this paper draws Critical Successful Factors(CSF) of PSS through multiple case study. First, we review various concepts and types in PSS and Platform business literature currently available on this topic. Second, after investigating various cases with the characteristics of PSS and platform business, we select four cases of 'iPod of Apple', 'Kindle of Amazon', 'Zune of Microsoft', and 'e-book reader of Sony'. Then, the four cases are categorized as successful and failed cases according to criteria of case selection and PSS classification. We consider two methodologies for the case selection, i.e., 'Strategies for the Selection of Samples and Cases' proposed by Bent(2006) and the seven case selection procedures proposed by Jason and John(2008). For case selection, 'Stratified sample and Paradigmatic cases' is adopted as one of several options for sampling. Then, we use the seven case selection procedures such as 'typical', 'diverse', 'extreme', 'deviant', 'influential', 'most-similar', and 'mostdifferent' and among them only three procedures of 'diverse', 'most?similar', and 'most-different' are applied for the case selection. For PSS classification, the eight PSS types, suggested by Tukker(2004), of 'product related', 'advice and consulancy', 'product lease', 'product renting/sharing', 'product pooling', 'activity management', 'pay per service unit', 'functional result' are utilized. We categorize the four selected cases as a product oriented group because the cases not only sell a product, but also offer service needed during the use phase of the product. Then, we analyze the four cases by using cross-case pattern that Eisenhardt(1991) suggested. Eisenhardt(1991) argued that three processes are required for avoiding reaching premature or even false conclusion. The fist step includes selecting categories of dimensions and finding within-group similarities coupled with intergroup difference. In the second process, pairs of cases are selected and listed. The second step forces researchers to find the subtle similarities and differences between cases. The third process is to divide the data by data source. The result of cross-case pattern indicates that the similarities of iPod and Kindle as successful cases are convenient user interface, successful plarform strategy, and rich contents. The differences between the successful cases are that, wheares iPod has been recognized as the culture code, Kindle has implemented a low price as its main strategy. Meanwhile, the similarities of Zune and PRS series as failed cases are lack of sufficient applications and contents. The differences between the failed cases are that, wheares Zune adopted an undifferentiated strategy, PRS series conducted high-price strategy. From the analysis of the cases, we generate three hypotheses. The first hypothesis assumes that a successful PSS system requires convenient user interface. The second hypothesis assumes that a successful PSS system requires a reciprocal(win/win) business model. The third hypothesis assumes that a successful PSS system requires sufficient quantities of applications and contents. To verify the hypotheses, we uses the cross-matching (or pattern matching) methodology. The methodology matches three key words (user interface, reciprocal business model, contents) of the hypotheses to the previous papers related to PSS, digital contents, and Information System (IS). Finally, this paper suggests the three implications from analyzed results. A successful PSS system needs to provide differentiated value for customers such as convenient user interface, e.g., the simple design of iTunes (iPod) and the provision of connection to Kindle Store without any charge. A successful PSS system also requires a mutually benefitable business model as Apple and Amazon implement a policy that provides a reasonable proft sharing for third party. A successful PSS system requires sufficient quantities of applications and contents.

• Information Systems Review
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• v.10 no.3
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• pp.39-64
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• 2008

As digital convergence evolves, it is expected that the market of IP-based services like VoIP and IPTV will be expanded. In particular, IPTV market is expected to attract consumers' attention through various interactive services offering a variety of experiences to consumers. Interactivity sets apart old media from new one in terms of how to mediate effects of user satisfaction. The object of this study is to investigate (1) multi-dimensional Interactivities in an interactive medium based on IP and relationship among them, and (2) significant factors affecting cognitive absorption of interactive media users. This study aims to provide implications on how to develop strategies for IP-based media including e-learning system.

• The Journal of the Korea Contents Association
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• v.8 no.10
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• pp.351-360
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• 2008

The purpose of this study is to segment visitors for beer franchise restaurants. Total of 308 questionnaires were distributed to the beer franchise restaurant customers of Kangnam area, Seoul. To accomplish the aim of this study, author took the following three steps. Firstly, literature review was done to find out selective attributes for restaurant and bar and market segmentation. secondly, Selective attributes of beer franchise were analyzed and five factors, -'additional service', 'side dish quality', 'service class', 'accessibility' and 'outlet image'- were extracted. Lastly, customers of beer franchise shop were divided into two groups by the selective attributes, -'simple visiting group' and 'active lover group'. Those variables-loyalty, intent to recommend and overall satisfaction- have significant influence on 'active lover group'. Other than that, other variables -demographic characteristics and customer's behavior characteristics- didn't play important role to distinct two groups. As a result, only basic information for setting up marketing strategy of each market was provided.

• Health Policy and Management
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• v.19 no.2
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• pp.21-35
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• 2009

Limited studies examined Medical Aid recipients' perception for amount of medical use. This study aimed to identify self-perception(optimal, under and overutilization) for amount, and real amount of medical use, and to determine factors associated with the perception. Subjects were 2,489 Medical Aid recipients among top 2% overusers in 2005. 200 case managers(CM) managing them conducted survey. CM interviewed them using 2005 medical claiming data from the Health Insurance Review & Assessment Service and structured questionnaire. Despite of overusers, perception of overutilization was only 26.9% and 23.6% in Class I and Class II, and that of underutilization was 21.4% and 18.7% respectively. In Class I, monthly total outpatient cost per capita of overutilization perception in 2006 was 206 thousand won higher than 150 thousand won of optimal utilization. Amounts of outpatient visit-days and prescribed cases of overutilization perception were higher than those of optimal and underutilization(p <0.0001). In Class II, overutilization perception had more prescribed cases(p 0.004). After adjustment of confounding factors including age and sex, the associated factors(odds ratio) with overutilization perception were hypertension(1.25), arthritis(1.32), depression(1.66), visit of multi medical institutions(3.09), and those of the underutilization were female(1.34), disabled(1.27), no family support(1.49), living in medium and small city(1.48), experience of unabled-visit to medical institution(2.54), frequent visit-recommendation from physician (1.36). In conclusion, education and consult are needed for subjects to improve the reasonable decision of medical use, and the self-care ability to manage diseases and symptoms. We suggest reinforcing the alternative service in community instead of costly medical institution.

• Journal of the Korean Society for Library and Information Science
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• v.47 no.1
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• pp.197-219
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• 2013

This study focused on current status of Korean public library services for people with intellectual disabilities, as well as problems associated with managing the services, in order to suggest future directions for implementation. To analyze the current status, the researcher conducted a case study of current Korean public library services for people with intellectual disabilities. This research also conducted a focus group interview with librarians experienced in providing such services. The results show that the services are provided with the support of a community welfare center, in the form of a program over short periods of time. The librarians agreed on the appropriateness of the services but emphasized various difficulties associated with service management. Based on the results, we suggest possible points of consideration, including support for increased funding, more qualified personnel, adequate policies, and development of a model service for people with intellectual disabilities.

• Journal of Service Research and Studies
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• v.6 no.2
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• pp.201-214
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• 2016

The main purpose of this paper was to review how luxury value is related to the consumer's conspicuous consumption and purchasing intention. The author formed luxury value which is including financial, functional, social, and individual value. In order to obtain the research results, the author conducted a survey and implemented statistical treatments. The results can be proposed as follows: First, financial, functional, social, and individual value was positively influencing on conspicuous consumption. Second, conspicuous consumption was impacting on intention to purchase. Third, it was suggested that the relative effect of individual value on conspicuous consumption was greater than other values. Thus it was concluded that consumers put a high value on conspicuous consumption.

• Journal of Digital Convergence
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• v.12 no.8
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• pp.113-127
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• 2014

The use of mobile devices offers a variety of services to the individuals and companies. On the other hand, security threats and new mobile security threats that exist in IT infrastructure to build the environment for mobile services are present at the same time. Services such as mobile and vaccine management services, such as MDM (Mobile Device Management) has attracted a great deal of interest in order to minimize the threat of security in mobile environment. These solutions can not protect an application that was developed for the mobile service from the threat of vulnerability of mobile application itself. Under these circumstances, in this paper, we proposed mobile application security checklists based on application security review items in order to prevent security accidents that can occur in a mobile service environment. We collected and analyzed Android applications, we performed a total inspection of the applications for verification of the effectiveness of the check items. And we checked that the check items through a survey of experts suitability was verified.

• International Commerce and Information Review
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• v.15 no.3
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• pp.87-110
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• 2013

The aim of this study is as follows. The first, What are the most important factors Affecting Global Single Window Usage and its Performance in Korean Trade Related Companies? The factors proposed for this study includes The pressure of trading companies in other country, Support of government, top management support, partnership among (makers distributors, retailers, customs service), education and training We gathered detailed data on our sample companies mainly from publicly available sources : Korea Customs Service. A structured questionnaire was used to collect information about: (1) general fact about the company (size, lines of business, products and services provided, employee, and some financial data about exporting), (2) To investigate the factors of the five contexts described above on korean export-import companies's global single window. The result are as follows. The analysis result revealed that the pressure of trading companies, support of government are influential variables on the affecting global single window in korean trade related companies.