• The Transactions of the Korea Information Processing Society
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• v.7 no.6
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• pp.1795-1802
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• 2000

In this paper, we propose an effective Noraebang service algorithm using multicasting technology. The goal of this proposed Noraebang service is to reduce the load of server as well as network resources and to enhance the performance of MOD. The effective Noraebang service algorithm proposes the new method that stores the post-ordered reserve songs in client's buffer in the order of request, not through the network and server, after the completion of the service pre-ordered requested song. The number of channel required in Noraebang service which used this algorithm can be decreased greatly when many songs re reserved, and the post-ordered songs can be serviced at real time by using buffer. The simulation results of this algorithm are confirmed that the performance of the proposed effective Noraebang service system increased significantly.

• Journal of Korean Institute of Industrial Engineers
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• v.30 no.2
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• pp.107-119
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• 2004

A study on the following parallel machine problem is addressed in this research. An order is completed only when a given number of processes (cycle) are repeated. Anew cycle is possible only upon the completion of the previous cycle. Orders are classified into job group according to product feature. For a machine to switch to a different job group from the currently processing one a major setup is required while a minor setup time is inserted in between two jobs of the same job group. The objective of the study is to find a schedule that minimizes total weighted tardiness. An initial solution is obtained by the RATCS(Restricted Apparent Tardiness Cost with Setup) rule, and a Tabu search is applied to improve the solution. Numerical examples are also presented.

• Microbiology and Biotechnology Letters
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• v.9 no.4
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• pp.191-196
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• 1981

In order to utilize the Koryangju distillers' grain for the acetic acid fermentation, the extracting methods and effects of the extracts on the fermentations were investigated. The result obtained are as follows. 1. Cold extracting method by which the distillers grain is extracted with 3 times of water for 60 hours at room temperature was better than hot extracting method in terms of the fermentation rate and the quality of vinegar product. 2. Optimum conditions and some results of surface fermentation based on the medium added by the extracts are as follows, optimum amount of the extracts to be added to the medium is 20-30% of total media; acetic acid production rate at log phase was 0.16g/100$m\ell$, hr.; recovery was 91.17%; and the time of 40 hours was required for the completion of fermentation. 3. Organoleptic quality of the vinegar which is produced by adding the extracts was superior to two commercial products examined.

• 연구논문집
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• s.34
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• pp.79-85
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• 2004

There are several types of life test method for hose assemblies. The two major tests used for hose assemblies are impulse test and burst test. And magnification adjustment of impulse pressure, heating of testing oil and repetitive motions of bending and straightening of testing hose are also performed for accelerating the life. According to the manufacture process of hose and swaging process of fitting, there is a difference in the life of hose assemblies from minimum 7 times to maximum 40 times during the life test in the same functioning condition. Like this, the life test of hose which has a wide scope of life distribution gives a problem that observation should take a long time to find out the existence of the bursting from the beginning of the test to the completion of bursting of hose assemblies. Therefore, this research proposes a process of concentrating on the defective section of hose assemblies and maximizing the life acceleration by giving 'Knockdown stress' to hose assemblies just until before the hose assemblies get out of order.

• Journal of the Korean Academy of Child and Adolescent Psychiatry
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• v.19 no.1
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• pp.28-37
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• 2008

Objectives : This study was conducted in order to examine the reliability and validity of the Children's Color Trails Test (CCTT). The objective of the study was also to provide the Korean normative data for the CCTT. Methods : Normative samples consisted of 766 children and adolescents living in Seoul and aged from 5 to 15 years. Eighty children who were diagnosed with ADHD, based on the DSM-IV criterion, were recruited from Seoul National University Children's Hospital. Among them, 46 ADHD children were receiving medication, while 34 children were drug-free. Results : The scores of the CCTT were significantly correlated with those of the Stroop test. Three factors were extracted through factor analysis-visual tracking and cognitive flexibility, distractibility and susceptibility to interference, and simple attention and impulsivity. The completion time of the CCTT for all children tended to decrease as age increased. There were significant differences in the CCTT scores between the ADHD group receiving medication, the ADHD-drug free group and the normal groups. The CCTT also showed sound test-retest reliability. These results confirmed the reliability and validity of the CCTT. Finally, we provided the Korean normative data for the CCTT. Conclusion : These results suggest that the CCTT is a reliable and valid test, which can be used to assess frontal function related to child psychiatric disorders in Korean children.

• Journal of the Korea Institute of Building Construction
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• v.12 no.6
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• pp.624-635
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• 2012

Construction projects, including housing, are carried out over long periods of time. According to changes to the construction period, the cost of input materials and wages also changes. Therefore appropriate management is important in order to minimize cost risks caused by fluctuations in prices. In Korea, housing units are usually sold in lots prior to construction completion. Therefore, careful management of input elements such as materials and equipment that are sensitive to price fluctuations is very important. This study deals with how the price fluctuation of materials, labor, and equipment influences the change of housing cost and seeks a way for cost management through identifying key resources sensitive to price fluctuation. As a result, a change to the housing cost index multiplies depending on cost changes of materials and labor together. Labor costs are a major factor on the housing cost index. In addition, certain types of materials and labor input to housing construction greatly influence price fluctuations. Thus, it is found that managing those main cost factors is the key for effective cost management.

• Journal of the Ergonomics Society of Korea
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• v.17 no.3
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• pp.61-70
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• 1998

The purpose of this paper is to evaluate the input methods of the numeric keypads that are widely used in various types of consumer and industrial electronic products. Three methods to enter numerals using keypads were compared: (1) Machine Intelligence, (2) + 100 key, and (3) Enter key input methods. Experiments were conducted to compare these three input methods for the channel selection of TV. Experimental prototypes which simulate TV user interfaces were developed using $RAPID^{TM}$ for usability testings. In the experiment, data on subject performance such as completion time, operational errors, and user interaction were collected through auto-logging method and video recording. After each test session, subjective preference was also asked using a questionnaire. In order to analyze the type of operation errors and the error causation, operation sequences were analyzed from the collected data. The Enter key input method showed better performance than other input methods. Based on these results. we can conclude that the input method using numeric keypads should be compatible with generic number counting(to input ch 7, it would be better to input 7 directly than to input 07 or 007) and should switch the channel as quickly as possible. This conclusion can be applied to the design of user interfaces which require numeral inputs.

• Journal of the military operations research society of Korea
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• v.22 no.2
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• pp.166-181
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• 1996

Aircraft survivability is determined by the susceptibility and the vulnerability. The aircraft susceptibility and vulnerability depend upon the hardware and software factors. Each of the hardware and software factors consisted of the qualitative and quantitative attributes varies according to the time of the mission. In order to establish the mathermatical model to analyze and evaluate the aircraft survivability, qualitative factors have to be transformed into quantitative factors. Even if many researches in the area of dynamic concept analysis and conversion of qualitative factors into the quantitative factors has been insufficient. This research enhances these insufficient area by developing a reliable aircarft survivability analysis method. The major areas of this research are as follows. First, a method for the conversion of the qualitative factors into the quantitative factors is developed by combining the Fuzzy Set Theory concept and the Delphi Technique. Second, by using the stochastic network diagram for the dynamic survivability analysis, the aircraft survivability and the probability of kill are calculated from the state probability for the situation during mission. The advantage of the analysis technique developed in this research includes ease of use and flexibility. In other words, in any given aircraft's mission execution under any variable probability density function, the developed computer program is able to analyze and evaluate the aircraft survivability.

• KIISE Transactions on Computing Practices
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• v.21 no.1
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• pp.58-63
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• 2015

In this work, we present a novel fountain code-based hybrid P2P storage system that combines cloud storage with P2P storage. The proposed hybrid storage system minimizes data transmission time while guaranteeing high data retrieval and data privacy. In order to guarantee data privacy and storage efficiency, the user transmits encoded data after performing fountain code-based encoding. Also, the proposed algorithm guarantees the user's data retrieval by storing the data while considering each peer's survival probability. The simulation results show that the proposed algorithm enables fast completion of the upload transmission while satisfying the required data retrieval and supporting the privacy of user data under the system parameters.

• Electronics and Telecommunications Trends
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• v.32 no.6
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• pp.105-115
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• 2017

This paper describes a project - based quality management model that identifies development technologies and codes while at the same time verifying the ability to implement processes that are essential in R & D projects. In order to verify the process implemented in the R & D project implementation, there are review, checking points, and evaluating methods the process performance levels for five processes such as defining requirements which is the beginning stage of system development, testing process which is the completion stage of system development, and project management and peer review process for project management and support in the proposed project-based quality management model. For development technology and code validation, the model included the documented test cases for each requirement by the developer in the requirements definition stage, debugging and testing in the design and implementation stages, static analysis and open source licence verification procedure, and system environment. After applying the model in SW development R&D project for evaluating the process performance, and verifying the development technology and the code, the developers responded that the improvement in the development technique and the code, and upgrade of process performance level for project are more than 10%.