• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.5
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• pp.657-666
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• 2017

In this study, factor analysis was performed to reduce the friction in the elevation motion of a stand for a 50-inchtelevision. Pipe type cross-section control was used for accurate positioning control of the piston rod. The pipe type was also compared with a labyrinth-type crosssection for the orifice. The frictional force was then reduced using gas seal lip technology. Specifications were chosen, and a volume compensation experiment was carried out using an apparatus for compensating the volume of the cylinder, which is compressed by the volume of the piston rod. Based on CAE and experimental considerations, the labyrinth-type orifice is preferred for reducing friction. For the gas seal lip technology, outer and inner diameters of ${\Phi}20$ and ${\Phi}8$ for the hollow rod were more appropriate when assuming the weight of a 50-inch television to be 30kgf. The third is that the result of total consideration in stability problem and performance of volume compensation for specification decision and volume compensation experiment is determined the final speculation of hollow rod ?8x?4 and riveting system. The last is that the labyrinth orifice is not founded that of the ${\O}0.4{\sim}0.6$ orifice both tests on 300 mm intervals.

• The KIPS Transactions:PartB
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• v.14B no.7
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• pp.513-522
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• 2007

Clustering is to divide given data and automatically find out the hidden meanings in the data. It analyzes data, which are difficult for people to check in detail, and then, makes several clusters consisting of data with similar characteristics. On-Line Document Clustering System, which makes a group of similar documents by use of results of the search engine, is aimed to increase the convenience of information retrieval area. Document clustering is automatically done without human interference, and the number of clusters, which affect the result of clustering, should be decided automatically too. Also, the one of the characteristics of an on-line system is guarantying fast response time. This paper proposed a method of determining the number of clusters automatically by geometrical information. The proposed method composed of two stages. In the first stage, centers of clusters are projected on the low-dimensional plane, and in the second stage, clusters are combined by use of distance of centers of clusters in the low-dimensional plane. As a result of experimenting this method with real data, it was found that clustering performance became better and the response time is suitable to on-line circumstance.

• KIPS Transactions on Computer and Communication Systems
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• v.6 no.6
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• pp.281-288
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• 2017

In Smart-cities, various types of integrated services must be linked to provide services to applications. Therefore, flexibility must be ensured between services so that various services can be efficiently provided. In order to secure the flexibility among services, it is very important to have a function to dynamically discover and invoke a desired service by searching for a semantic service by reflecting a recognized context through real-time context-aware in smart-cities. To date, quite a number of semantic service discovery techniques have been developed. However, they have not been verified as suitable for use in the smart-city domain. In this study, we tried to verify the existing ones to use a suitable one. We tested most of existing semantic service discovery techniques, but we found that none of them is suitable to our research. Therefore, we developed our own semantic service discovery technique. This paper introduces our work and presents the performance evaluation results that demonstrate that our developed works well and show good performance. For the performance evaluation, the experimental system was actually constructed and the real performance was measured. In the experiment, we implemented the semantic service discovery scenario that dynamically searches and calls the services needed to provide fire accident management services in smart cities.

• Journal of Korean Society of Archives and Records Management
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• v.12 no.3
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• pp.155-176
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• 2012

Economic impact analyses have not been widely conducted in archives. This article reports on a two parallel surveys in the US and Canada to assess the economic impact of government archives (state, provincial, territorial, county, and municipal). The surveys utilize indirect measures of economic impact. Responses from 2,534 people in 66 archives were analyzed. Findings indicate that archives were the primary reason that respondents visited an area and that visitors exhibit specific patterns of visiting the archives in conjunction with other cultural organizations in an area. Furthermore, while many respondents used local eateries, fewer rented lodgings or spent money on theater or sporting events. As a result, the archives participating in this survey did have a modest impact on local economies. The article concludes by discussing three major questions about the evaluation of the economic impact of archives which were raised by the findings: 1) Are indirect measures the most appropriate means of assessing economic impact in archives or should archives employ direct measures as used by public libraries? 2) How should government archives formulate their value proposition and should those value propositions focus on other aspects of archives' impact, such as the social impact, to demonstrate archives' important role in society? and 3) Since visitors exhibited distinct visitation patterns, should archives work more with these other aligned organizations and work on larger forms of collective impact that benefit the entire cultural heritage sector in an area?

• Korean Journal of Remote Sensing
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• v.29 no.4
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• pp.361-373
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• 2013

The monitoring of urban area, target detection and building reconstruction have been actively studied and investigated since high resolution X-band SAR images could be acquired by airborne and/or satellite SAR systems. This paper describes an efficient approach to reconstruct artificial structures (e.g. apartment, building and house) in urban area using high resolution X-band SAR images. Building footprint was first extracted from 1:25,000 digital topographic map and then a corner line of building was detected by an automatic detecting algorithm. With SAR amplitude images, an initial building height was calculated by the length of layover estimated using KS-test (Kolmogorov-Smirnov test) from the corner line. The interferometric SAR phases were simulated depending on SAR geometry and changable building heights ranging from -10 m to +10 m of the initial building height. With an interferogram from real SAR data set, the simulation results were compared using the method of the phase consistency. One of results can be finally defined as the reconstructed building height. The developed algorithm was applied to repeat-pass TerraSAR-X spotlight mode data set over an apartment complex in Daejeon city, Korea. The final building heights were validated against reference heights extracted from LiDAR DSM, with an RMSE (Root Mean Square Error) of about 1~2m.

• Korean Journal of Remote Sensing
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• v.33 no.2
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• pp.213-230
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• 2017

The satellite-based red tide detection algorithms have been developed for specific occurrence waters and red tide species. However, it is essential to study the whole occurrence waters and various red tide species for quick and accurate surveillance of red tide around the Korean coastal waters. In thisstudy, the comprehensive analysesinvolve the spectral features of red tide areas and the suitability of the satellite-based red tide detection algorithms used with GOCI in the Korean coastal waters. As a result, the spectral characteristics were changed according to the chlorophyll content of red tide species and the turbidity of the waters where the red tide appeared. In addition, the previous red tide detection algorithm is applied to GOCI, and it is found that there is a limitation to the red tide area extraction as the existing threshold value. To overcome these limitations, red tide species were divided into two groups according to the difference of chlorophyll content and a system for red tide surveillance wassuggested. It is possible to distinguish between red tide and non-red tide area through five steps. As a result of applying to GOCI, the red tide was appropriately extracted from the previous algorithm based on red tide breaking news. If such a red tide surveillance system is used, it will be possible to efficiently monitor red tide by quick and accurate surveillance of the whole occurrence waters around the Korean and various red tide species.

• Korean Security Journal
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• no.44
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• pp.117-137
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• 2015

As school violence gets serious, the school system created the local board against school violence in order to respond to school violence effectively. Yet, there are not many studies about the effectiveness of the local board against school violence. A few studies investigated teachers' perception about the local board while the information about the school resource officers' perception is not known much. The current study surveyed school resource officers about their perception towards the function of the local board, its member, and the response of the principal to school violence. Participants are the school resource officers working for the four metropolitan police agencies(Seoul, Kyunggi, Busan, and Ulsan) in Korea, and were asked to answer to structured and open-ended questions. The results indicated that the officers thought the local board did not very well for the function of protecting the victim's rights. In addition, they believed that the participation of parents needs to be limited in the membership, and more experts should be included in the membership of the local board. They also thought the principals should be tough in dealing with school violence. The discussion includes ideas about improving professionalism of the membership and making changes on the related regulations.

• Korean Security Journal
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• no.44
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• pp.199-223
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• 2015

The purpose of this study is to find the development of the personal protection business plan based on the problem that guards are now aware of personal protection service. In order to achieve the objectives of this study, we analyzed the data after expert survey and interview conducted by seven experts engaged in personal protection services more than 15 years. The guard who perform personal protection service proposed a development plan of personal protection services as follows. First, the current education system for new employees' training is required to improve the educational program of 40 hours in subjects related to personal protection duties by reorganization Second, the personal protection service training for guards also appropriate to switch to 8-hour training program for three months through an educational organization controlled by country. Third, the personal protection guards should be proceeding the practical programs required in the field and quality education in the different section by competent and professional instructors. Fourth, it should be revised Regulating that on the site of collective civil petition including in Events related to events across the board in the security services law. Fifth, there needs to be a change of recognition between police and private security firms, and to be set up the organization for supervision of management by police and private security firms jointly. Sixth, there needs to be organized a subcommittee which is consisting of experts in each task on Korea Security Association, and founded Korea Personal Protection Association for development associated with the personal protection service and to protect the rights of personal protection guards.

• The Korean Journal of Applied Statistics
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• v.31 no.3
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• pp.367-382
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• 2018

Prediction models for a corporate bond rating in existing studies have been developed using various models such as linear regression, ordered logit, and random forest. Financial characteristics help build prediction models that are expected to be contained in the assigning model of the bond rating agencies. However, the ranges of bond ratings in existing studies vary from 5 to 20 and the prediction models were developed with samples in which the target companies and the observation periods are different. Thus, a simple comparison of the prediction accuracies in each study cannot determine the best prediction model. In order to conduct a fair comparison, this study has collected corporate bond ratings and financial characteristics from 2013 to 2017 and applied prediction models to them. In addition, we applied the elastic-net penalty for the linear regression, the ordered logit, and the ordered probit. Our comparison shows that data-driven variable selection using the elastic-net improves prediction accuracy in each corresponding model, and that the random forest is the most appropriate model in terms of prediction accuracy, which obtains 69.6% accuracy of the exact rating prediction on average from the 5-fold cross validation.

• The Korean Journal of Applied Statistics
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• v.31 no.5
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• pp.637-653
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• 2018

Rapid aging of the population affects population structure and population aging. Consequently, developed countries have focused on population aging as a major issue in regards to pension sustainability finances as well as health and the elderly welfare system. Mortality projections that result from population structure changes and population aging are increasingly important. This paper compares six mortality models using KOSTAT's life table from 1970 to 2016. The models are rooted in the Lee-Carter (LC) model (Lee and Carter, Journal of the American Statistical Association, 87, 659-671, 1992) and have been modified and improved on the assumptions of the LC model. We examined the improvement process and the check assumption by models in order to find a suitable mortality model for Korea. Korea shows rapid aging and declined mortality rate by age; therefore, it is desirable to estimate and predict mortality from LL&LC-ER models by combining LC-ER, LL, and LC-ER models that reflect the phenomena and modify age-specific mortality patterns without major changes in expected life expectancy.