• 한국경영과학회지
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• 제34권3호
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• pp.43-53
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• 2009

The pallet loading problem(PLP) requires the best orthogonal layout that loads the maximum number of identical boxes(small rectangle) onto a pallet(large rectangle). Since the high pallet utilization saves the distribution and storage costs, many heuristic and exact algorithms have been developed so far. Martins and Dell have found the optimal layouts for the all PLPs less than or equal to 100 boxes except for only 5 problems in their recent research. This paper defines the 'stair structure' and proposes a new exact algorithm applying it. In order to show the priority of the proposed algorithm, computational results are compared to previous algorithms and the optimal layouts for the S unsolved problems are given.

• 한국학교수학회논문집
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• 제5권1호
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• pp.111-122
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• 2002

The purpose of this study was to examine high school second graders' understanding of the basic nature of logarithm, the major type of error they made about logarithmic function and the cause of such an error, and to seek ways to instruct it better. For that purpose, three research questions were posed: 1. Investigate how much high school students in their second year comprehend the nature of logarithm. 2. Analyze what type of error they make about logarithmic function. 3. Analyze the cause of their error according to the selected error models and how it could be taught more efficiently. The findings of this study were as below: First, the natural science students had a better understanding of the basic nature of logarithm than the academic students. What produced the widest gap between the two groups' understanding was applying the nature of logarithm to the given problems, and what caused the smallest gap was the definition of logarithm and the condition of base. Second, the academic students had a poorer understanding of the basic nature of logarithmic function graph and of applying the nature of logarithm to the given problems. Third, the natural science students didn't comprehend well the basic nature of logarithmic function graph, the nature of characteristics and mantissa. Fourth, for all the students from academic and natural science courses, the most common errors were caused by the poor understanding of theorem or nature of the ［E4] model. Fifth, the academic students made more frequent errors due to the unfamiliar signs of the ［El］ model, the imperfect understanding of theorem or nature of the ［E4］ model, and the technical part of the ［E6］ model. Sixth, the natural science students made more frequent errors because of the improper problem interpretation of the ［E2］ model and the logically improper inference of the ［E3］ model.

• 경영과학
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• 제29권2호
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• pp.91-103
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• 2012

Revenue management problems originated in the 1970's in the context of the airline industry have been successfully introduced in airline industries. It has started on the capacity control by booking classes for available seats, and has been recognized as a powerful tool to maximize the total revenue. Changing customer behavior and airline market environments, however, has required a new mechanism for improving the revenue. Dynamic pricing is one of innovative tools which is to adjust prices according to the market status. In this paper, we consider a dynamic pricing and seat control problem for discrete time horizon. The problem can be modeled as a stochastic programming problem. Applying the linear approximation technique and given the price set for each time, we suggest a mixed Integer Programming model to solve our problem efficiently. From the simulation results, we can find our model makes good performance and can be expanded to other comprehensive problems.

• 한국건설관리학회논문집
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• 제13권4호
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• pp.3-15
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• 2012

현재 BIM을 도입한 주요 국가들은 BIM 발주 또는 납품 전 단계에서 설계사가 설계과정 중 기본적인 품질 확보가 가능하도록 필요한 지침을 제공하고 있다. 그러나 국내 건설산업의 경우, BIM의 도입 및 적용은 확산되고 있으나, BIM 발주 시 설계품질을 고려한 지침은 제공되지 않고 있다. 이로 인해 설계사는 자의적 해석에 의존적일 수밖에 없으며, 발주자는 납품받은 BIM 데이터의 품질을 신뢰하기 힘든 상황이다. 또한, BIM 소프트웨어의 내부 오류는 파악할 수 없는 관계로 자체 포맷에 의한 품질검토는 BIM 데이터의 품질을 확보하기 어렵다. 따라서 BIM 데이터의 품질을 높이기 위해서는 개방형 BIM(IFC)을 활용한 객체모델링과 객체별 속성 정의 등을 포함하는 지침을 개발할 필요가 있다. 이는 BIM 데이터의 기본 품질을 보증하고, 품질검토를 통하여 좀 더 나은 품질을 확보하는데 활용될 수 있다. 이에 본 연구는 설계품질 향상을 위한 개방형 BIM기반의 품질관리 방안으로 해외 주요 국가들의 선진사례와 품질검토 소프트웨어를 조사 분석하여 기본적인 품질관리가 가능한 요구조건을 제시하였고, 기존 BIM 사례에 적용하여 요구조건의 유용성을 검토하였다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제8권9호
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• pp.3231-3249
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• 2014

Deniable encryption, introduced in 1997 by Canetti, Dwork, Naor, and Ostrovsky, guarantees that the sender or the receiver of a secret message is able to "fake" the message encrypted in a specific ciphertext in the presence of a coercing adversary, without the adversary detecting that he was not given the real message. Sender - side deniable encryption scheme is considered to be one of the classification of deniable encryption technique which defined as resilient against coercing the sender. M. H. Ibrahim presented a sender - side deniable encryption scheme which based on public key and uncertainty of Jacobi Symbol [6]. This scheme has several problems; (1) it can't be able to derive the fake message $M_f$ that belongs to a valid message set, (2) it is not secure against Quadratic Residue Problem (QRP), and (3) the decryption process is very slow because it is based dramatically on square root computation until reach the message as a Quadratic Non Residue (QNR). The first problem is solved by J. Howlader and S. Basu's scheme [7]; they presented a sender side encryption scheme that allows the sender to present a fake message $M_f$ from a valid message set, but it still suffers from the last two mentioned problems. In this paper we present a new sender-side deniable public-key encryption scheme with fast decryption by which the sender is able to lie about the encrypted message to a coercer and hence escape coercion. While the receiver is able to decrypt for the true message, the sender has the ability to open a fake message of his choice to the coercer which, when verified, gives the same ciphertext as the true message. Compared with both Ibrahim's scheme and J. Howlader and S. Basu's scheme, our scheme enjoys nice two features which solved the mentioned problems: (1) It is semantically secure against Quadratic Residue Problem; (2) It is as fast, in the decryption process, as other schemes. Finally, applying the proposed deniable encryption, we originally give a coercion resistant internet voting model without physical assumptions.

• 한국IT서비스학회지
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• 제8권4호
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• pp.175-185
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• 2009

Objectifying claims filed during the warranty period, analyzing the current circumstances and improving on the problem in question is an activity worth doing that could reduce the likelihood of claims to occur, cut down on the costs, and enhance the corporate image of the manufacturer. Existing analyses of claims are confronted with two problems. First, you can't precisely assess the risks of claims involved by means of the value of claims per 100 products alone. Second, even in a normal state, the existing approach fails to capture the probabilistic conflicts that escape the upper control limit of claims, thus leading to wrong control activities. To solve the first problem, this paper proposed that a time series detection concept where the claim rate is monitored based on the date when problems are processed and a hazard function for expression of the claim rate be utilized. For the second problem, this paper designed a model whereby to define a normal state by making use of PID (Proportion, Integral, Differential) and infer by way of a fuzzy concept. This paper confirmed the validity and applicability of the proposed approach by applying methods suggested in the actual past data of warranty claims of a large-scaled automotive firm, unlike hypothetical simulation data, in order to apply them directly in industrial job sites, as well as making theoretical suggestions for analysis of claims.

• Journal of Computing Science and Engineering
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• 제2권4호
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• pp.394-411
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• 2008

The data in automation and control systems can be achieved not only from different field devices but also from different OPC (OLE for Process Control) servers. However, current OPC clients can only read and decode the simple data from OPC servers. They will have some problems to acquire structured data and exchange the structured data. In addition to the large network control systems, the OPC clients can read, write, and subscribe to thousands of data points from/to OPC servers. Due to that, the most important factor for building a high performance and scalable industrial control system is the ability to transfer the process data between server and client in the most efficient and fastest way. In order to solve these problems, we propose a means to implement the OPC DA (Data Access) server supporting the OPC complex data, so that the OPC DA clients are able to read and decode any type of data from OPC servers. We also propose a method for caching the process data in large industrial control systems to overcome the limitation of performance of the pure OPC DA system. The performance analysis and discussion indicate that the proposed system has an acceptable performance and is feasible in order for applying to real-time industrial systems today.

• 공학교육연구
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• 제19권1호
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• pp.3-10
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• 2016

This study was conducted to identify Korea's TRIZ research trends and to propose implications for setting a direction for future TRIZ research by analyzing TRIZ-related research over the past 15 years, or from 1998 to 2013. The subjects in this study were 256 published studies, including 149 studies in academic journals, 97 master theses, and 10 doctorate theses. This study reached the following conclusion. First, academic journals were the most frequent form of publication of TRIZ-related studies, followed by master's degree theses, and doctorate theses. Second, two or more TRIZ tools were used to solve problems and the most frequently used topic was technical contradiction as the result of frequency analysis for TRIZ research topics. This signified that it was easier to solve problems when various TRIZ tools were used, rather than applying a single TRIZ tool while technical contradiction was considered to be actively used as it allowed the relatively easy understanding of TRIZ. Third, the use of TRIZ research topics had increased and diversified each year. This could be interpreted to be based on the increased understanding of TRIZ. Fourth, case studies and experimental research were the most frequently used methods in TRIZ-related research. This was because various TRIZ tools were applied on problem solving situations, which were directly proposed as the research result. Fifth, the use of TRIZ was increasing in the educational field. Specifically, it was noted that TRIZ was used in creativity education with the use of 40 invention principles in elementary, middle, and high schools.

• Journal of Acupuncture Research
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• 제15권2호
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• pp.511-518
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• 1998

Aqua-acupuncture therapy is a new acupuncture-therapy that cures diseases by needling with direct medication of oriental or western medicine at acupuncture points which are related to a disease, pressure pain points or positive reaction points according to meridian theory, followed by controlling one's body function and relieving the pathogenic state. Recently, the method is widely applied clinically owing to its handiness and usefulness, but it is pointed that it has some problems. Therefore, the present studies have been carried out to introduce history of the method, materia-medica which is ordinarily used, acupuncture points to be selected, handling method, mechanism of action, range of application and some points to be careful. Moreover, through the experiences that we have made by applying the method clinically, we suggest that the following study should be carried out : First, clinical application of needling with direct medication should be made by using materia-medica which is already proved safe. Second, it is essential to study the side-effects accompanying fever, pains, mass and hemolysis after the method is applied. Third, the study on the mechanism of action of the method should be accomplished continuously.

• 한국물환경학회지
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• 제33권1호
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• pp.90-96
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• 2017

Many sewage treatment plants have applied the advanced technology of chemical coagulant system to remove phosporus in Korea. However there are some problems for the injection of optimum coagulant dosage. In order to solve these problems, the research related to the more cost-effective automatic total phosphorus coagulation control system using an EC(Electrical Conductivity) have been in progress. This study was conducted by the same process and operation method as the Lab-scale for public small town sewage treatment plant. First, it confirmed the correlation among the EC, PO4-P and coagulant dosage in the Lab-scale MSBR(Membrane Sequencing Batch Reactor) process. Next, it analyzed that correlation coefficient of EC and the coagulant dosage was 0.92 in the Full-scale MSBR process. As a result, not only T-P removal efficiency was doubled but also it satisfied the effluent water quality standard in a stable manner. In addition, by applying the automatic control system using the EC, compared to the fixed coagulant injection system the coagulant dosage could be reduced by 28%.