• Proceedings of the Korean Society of Computer Information Conference
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• 2013.01a
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• pp.1-2
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• 2013

본 논문에서는 안드로이드의 고질적인 문제점인 사용자 반응성 문제 해결을 위한 연구를 소개한다. 특히 여러 응용들이 동시에 수행되는 경우 대화형 응용이 다른 응용들에 밀려 원하는 만큼 CPU를 얻지 못하는 상황에서 발생하는 반응지연 문제에 초점을 맞추고 이를 극복하기 위한 연쇄적 우선순위 상승 기법을 제시한다. 이 기법은 대화형 웅용뿐만 아니라 기존 연구에서 고려하지 않은 터치 관련 이벤트 처리 스레드들과 대화형 응용의 자식 스레드들의 우선순위를 연쇄적으로 상향시킴으로써 터치에 대한 응답시간을 줄인다. 본 논문에서는 제안한 기법을 상용 스마트폰에 적용하여 유용성을 검증하였다. 실험 결과에 따르면 기존 안드로이드에 제안한 기법을 적용한 경우 평균반응시간이 기존의 31.91%로 감소하였다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.38B no.5
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• pp.315-327
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• 2013

Wireless Body Area Network (WBAN) is a network around a human body within 3~5m which consists of medical or non-medical device. WBAN has to satisfy many kinds of demands such as low-power, a variety of data rate and a data priority. Especially, it is hard for the nodes for monitoring vital signs to replace battery. Thus energy and channel efficiency is important because the battery power is limited. In this thesis, a novel algorithm for reducing the energy consumption is proposed. The proposed algorithm adjusts transmission period according to traffic. by means of determining transmission period by amount of data, the node can reduce energy consumption. Energy detection is performed in order to guarantee data priority before attempting to transmit. In case of failing to transmit, it is proposed that energy consumption is reduced through avoiding collision by changing priority. The comparison result shows that the proposed algorithm reduces power consumption and increasing maximum channel efficiency by avoiding collision.

• Proceedings of the Korea Water Resources Association Conference
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• 2019.05a
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• pp.101-101
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• 2019

전 지구적 기온상승으로 인한 기후변화는 사회적, 수문학적, 다양한 분야에 영향을 미친다. 또한 IPCC(Intergovernmental Panel on Climate Change)의 보고서에 따르면 미래에도 지속적으로 기온상승이 예상되며, 이러한 현상은 인류의 삶에 큰 영향을 미칠것으로 예상된다. 또한 수자원 및 관련 분야에서도 기온 상승에 따른 강수량, 강수의 주기 변동, 극한 기후사상의 심도(severity)와 빈도 변화에 따른 다양한 연구가 진행되고 있으며, 미래의 강우량과 온도를 예측하는 기후변화연구에서는 다양한 기후모형을 고려하여 분석한다. 하지만 모든 기후모형이 우리나라에 적합한 것은 아니므로 과거 기후를 모의한 결과를 토대로 성능이 뛰어난 모형의 결과에 더 높은 가중치를 주고 미래를 예측하는 연구가 활발히 진행되고 있다. 일반적으로 기후모형으로 GCM (General Circulation Model) 모의 결과가 이용되는데 우리나라에 대한 GCM 결과의 정확성을 분석하는 연구는 부족한 실정이다. 따라서 본 연구에서는 21개의 GCM을 대상으로 과거 모의 자료(1970년~2005년)를 실제 관측소에서 관측된 강수량과 비교하여 각 GCM들의 성능을 평가하고 이를 토대로, GCM들의 우선순위를 선정하였다. 또한 격자 기반 GCM 결과를 IDW (Inverse Distance Weighted) 방법을 사용하여 기상관측소로 지역적 상세화를 수행하였으며, GCM과 관측자료 사이의 편이를 보정하기 위해 6가지의 Quantile Mapping 방법과 Random Forest 기법을 사용하였다. 또한 편이 보정 기법 중 성능이 좋은 기법을 선택하여 관측소에 적용하였다. 편이 보정된 GCM 모의결과에 대한 성능을 토대로 우수한 GCM 순위를 도출하기 위해 다기준의사결정기법 중 하나인 TOPSIS (Technique for Order of Preference by Similarity to Ideal Solution)를 이용하였다. 그리고 GCM의 전망기간인 2010년부터 2018년까지의 Machine learning 방법과 Quantile mapping의 기법을 비교 및 성능이 우수한 편이 보정 방법을 선택한 후 전망기간 동안의 GCM 성능의 우선순위를 선정하였다.

• Proceedings of the Korea Information Processing Society Conference
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• 2000.04a
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• pp.61-66
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• 2000

본 논문에서는 분산 실시간 데이터베이스 시스템을 위한 효율적인 동시성 제어 기법을 제안한다. 제안하는 기법은 분산 실시간 환경에서 완료준비 단계에 도달한 트랜잭션의 우선 순위를 상승시킴으로써 트랜잭션의 재시작에 의한 낭비를 줄이고, 트랜잭션의 완료를 최대한 보장하며, 잠금 지연 시간을 최소화하는 장점을 갖는다. 또한, 제안하는 기법은 우선 순위가 상승된 트랜잭션의 완료를 보장하며 데이터 차용(borrowing)을 통해 다른 트랜잭션의 지연시간을 줄여줌으로써 전체적인 시스템 성능을 향상시킨다.

• Journal of Digital Convergence
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• v.14 no.7
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• pp.145-154
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• 2016

The purpose of this study was to carry out comparative analysis on the world major liner shipping companies' ship investment strategy using Fuzzy-AHP model. In this study, the ship investment factors were firstly selected by literature review and finally adopted them by in-depth interview with experts who had working experiences over 15 years in the field of shipping business. As suggested in the previous research, the liner shipping companies have been classified into four types such as 'ship investment irrelevant to market trend'(Type1), 'ship investment before market rise'(Type2), 'market decline after participation in excessive orders'(Type3), 'avoidance of ship investment during market rise'(Type4) and the comparative analysis were conducted among four ship investment types. According to the results of analysis, ship investment priority in Type1 was freight rates(0.132), price of used ship(0.121) and fleet(0.103). The priority in Type2 was freight rates(0.134), need for ship owner(0.113) and public funding(0.109). Type3 put its priority in freight rates(0.173), fleet(0.169) and the changes in international circumstances(0.121). Type4 considered freight rates(0.239), fleet(0.232) and oil price(0.150) as its priority.

• The Journal of the Korea Contents Association
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• v.13 no.4
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• pp.389-398
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• 2013

This study aims to support rational security investment decision making through prioritizing on operational level of management measures strategically, in carrying out industrial security activities. For this, AHP survey is conducted against industrial security professionals and analyzed. Thereafter, the importance and the priority of industrial security management measures are determined. As a result, in a comparison evaluation among the criteria, 'ICT service management' represents the highest weight (0.54). And the sub-criteria could be divided into three groups (Group I, II, III), depending on their importance. The sensitivity analysis results show that if the weight of the criterion, 'ICT systems/networks access control' is doubled, the sub-criteria, 'O/S access control', 'application access control', and 'wired/wireless network access control' are enter into top rank group. In case of the criterion, 'physical/environmental security' is doubled, the sub-criteria, 'protection zoning/access control' and 'disaster prevention on business equipment/counter-terrorism' are enter into the top rank group, 'securing utilities' is enter into the mid rank group.

• Korean Journal of Construction Engineering and Management
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• v.12 no.5
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• pp.146-154
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• 2011

Korean contractors have been maintained sustainable growth since entering into overseas construction market for the first time in 1960' s. In 2010, Korean contractors ordered 761 billion (USD) from overseas markets. Especially, billion (USD) were earned by Korean contractors in overseas plant construction market which account for more than 80% of the total amount by Korean contractors. Nevertheless, many Korean contractors are suffering from lack of technological competitiveness and construction management skills in the design phase compared with global leading contractors. These conditions have directly effect on the success of projects in terms of cost, duration, and quality. So, this study focused on identifying the risk factors and developing risk priority method for the design phase of LNG plant projects whose market is expanding. Research procedures were conducted by the following three steps. First, total 57 risk factors were identified in design phase through extensive literature reviews and experts survey. Second, the authors developed risk priority method which are more suitable for design phase of LNG plant projects by using three criteria, Probability(P), Impact(I), and Coordination Index(CI). Finally, the suitability of risk priority method and practical applicability were verified through expert survey and interview. Consequently, if korean contractors use the suggested risk factors and priority method based on their own know-how and experiences, then more reasonable and rational risk management will be conducted in the design phase of LNG plant projects.

• Korean Chemical Engineering Research
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• v.60 no.3
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• pp.347-355
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• 2022

The safety valve (PSV) is a safety device that automatically releases a spring when the pressure generated by various causes reaches the set pressure, and is restored to a normal state when the pressure falls below a certain level. Periodic inspection and monitoring of safety valves are essential so that they can operate normally in abnormal conditions such as pressure rise. However, as the current safety inspection is performed only at a set period, it is difficult to ensure the safety of normal operation. Therefore, evaluation items were developed by finding failure modes and causative factors of safety valves required for safety management. In addition, it is intended to provide decision-making information for securing safety by deriving the priority of items. To this end, a Delphi survey was conducted three times to derive evaluation factors that were judged to be important in relation to the Failure Mode Cause Factor (FMCFs) of the safety valve (PSV) targeting 15 experts. As a result, 6 failure modes of the safety valve and 22 evaluation factors of its sub-factors were selected. In order to analyze the priorities of the evaluation factors selected in this way, the hierarchical structure was schematized, and the hierarchical decision-making method (AHP) was applied to the priority calculation. As a result of the analysis, the failure mode priorities of FMCFs were 'Leakage' (0.226), 'Fail to open' (0.201), 'Fail to relieve req'd capacity' (0.152), 'Open above set pressure' (0.149), 'Spuriously' 'open' (0.146) and 'Stuck open' (0.127) were confirmed in the order. The lower priority of FMCFs is 'PSV component rupture' (0.109), 'Fail to PSV size calculation' (0.068), 'PSV Spring aging' (0.065), 'Erratic opening' (0.059), 'Damage caused by improper installation and handling' (0.058), 'Fail to spring' (0.053), etc. were checked in the order. It is expected that through efficient management of FMCFs that have been prioritized, it will be possible to identify vulnerabilities of safety valves and contribute to improving safety.

• Journal of KIISE:Databases
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• v.28 no.3
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• pp.484-493
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• 2001

As real-time database systems are extended to the distributed computing environment, the need to apply the existing real-time concurrency control schemes to the distributed computing environment has been made. In this paper we propose an efficient concurrency control scheme for distributed real-time database system. Our proposed scheme guarantees a transaction to commit at its maximum, reduces the restart of a transaction that is on the prepared commit phase, and minimizes the time of the lock holding. This is because it raises the priority of the transaction that is on the prepared commit phase in the distributed real-time computing environment. In addition, it reduces the waiting time of a transaction that owns borrowed data and improves the performance of the system, as a result of lending the data that the transaction with the raised priority holds. We compare the proposed scheme with DO2PL_PA(Distributed Optimistic Two-Phase Locking) and MIRROR(Managing Isolation in Replicated Real-time Object Repositories) protocol in terms of the arrival rate of transactions, the size of transactions, the write probability of transactions, and the replication degree of data in a firm-deadline real-time database system based on two-phase commit protocol. It is shown through the performance evaluation that our scheme outperforms the existing schemes.

• Korea Trade Review
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• v.42 no.1
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• pp.1-25
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• 2017

By applying the AHP(Analytic Hierarchy Process), we have analyzed the importance and the order for priorities to the management risk factors of Korean SMEs & Venture companies in China. The major management risk factors of manufacturing companies were the rise in labor costs followed by fierce competition in the marketplace, problems involved with human resource management and the rise in the cost of materials. In the case of companies manufacturing electronic products, the rise of labor costs and alteration in government's tax policy were seen as the main risk factors. In the case of chemical product manufacturing companies, the reinforcement of environmental protection law and in automobile component manufacturing companies, apart from the rise in labor cost, the increase in raw materials costs were analyzed as the main risk factors. While considering the time period, the main risk factors of the companies that entered China in the 1990's were fierce competition and alteration in government's tax policy and for the companies that entered China in the 2000's, increase in raw material cost, the rise in labor cost etc were analyzed to be the main risk management factors.