• Korean Journal of Construction Engineering and Management
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• v.10 no.5
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• pp.85-94
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• 2009

For the purpose of analysing the capability (knowledge, experience, and ability) of CM at Risk in the major construction company in korea, this study performed questionnaire survey with experts in the companies. Based on the analysis of the survey, the study was found as follows. 1) It is needed to increase the capability of preconstruction services, such as project management plan/manual, contract documents, value engineering, alternative analysis, time management, and claim. 2) Despite of gap of the capability between the present and the future CM services, the study concluded that the capability is sufficient to perform CM at Risk project in the major construction company.

• The KIPS Transactions:PartC
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• v.12C no.3 s.99
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• pp.395-400
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• 2005

The IEEE 802.11b WLAN supports multiple transmission rates and the rate is chosen in an adaptive manner by an auto rate control algorithm. This auto rate control algorithm deeply affects the total system performance of the IEEE 802.11b WLAN. In this paper, we examine the WLAN performance with regard to the auto rate control algorithm especially the ARF scheme. The experimental results indicate that the ARF scheme works well in the face of signal noise due to node location. However, the ARF scheme severely degrades system performance when multiple nodes contend to obtain the wireless channel and the packet is lost due to signal collision. In addition, TCP prevent the performance degradation due to ARF scheme by retaining number of active nodes. However, some applications, such as transporting multimedia data, adopt the UDP. Therefore, the TCP cannot be an optimal solution for all WLAN applications.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.13 no.10
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• pp.2088-2096
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• 2009

This paper deals with hybrid MAC protocol design for underwater acoustic networks. The proposed MAC protocol has the cluster structure with a master node and slave nodes, and the hybrid network structure that combines a contention free period based on TDMA(Time Division Multiple Access) with a contention period. The suggested MAC protocol has a beacon packet for supervising network, a guard period between time slots for packet collision, time tag for estimation of propagation delay with a master node, the time synchronization of nodes, entering and leaving of network, and the communication method among nodes. In this paper, we adapt the proposed hybrid MAC protocol to AUV network, that is the representative mobile device of underwater acoustic network, and verify this protocol is applicable in real underwater acoustic network environment.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.3
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• pp.1409-1415
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• 2013

With the development of Internet communication and the use of a variety of online services has been greatly expanded. Therefore, the importance of authentication techniques for users of online services has increased. The most commonly used methods for user authentication is a technique that utilizes a prearranged password. However, the existing password scheme for authentication must use the same password every time. Therefore, the password being leaked by attackers, it can be used maliciously. In this paper, we proposed the Variable Password Generation Method in Internet Authentication System that generates a new password using information such as the access date, time, and IP address when user logs in. The method proposed in this paper prevents disclosure of personal information due to password exposure and improves the reliability and competitiveness in the field of security systems.

• 사회경제평론
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• v.29 no.1
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• pp.1-29
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• 2016

This paper looks critically, in the light of the Capital Controversies of the 1950s and the 1960s, at the Neoclassical claim that the Funded-Pension system is economically superior to the Pay-As-You-Go (PAYG) pension system. This claim rests crucially upon the inverse relation between the rate of interest and the volume of investment (the investment demand function) and the positive relation between the capital intensity and labour productivity (the 'intensive- form' production function), The Capital Controversies proved that the two relations do not always hold; then, the claim in question loses much of its ground. Further, the absensce of the relations makes plenty room for effective demand in determining the level of income and the volome of employment even in the long period. This positive role of effective demand in the long period highlights the problems of the Funded-Pension system and, at the same time, supports the competitiveness of the PAYG pension system.

• Proceedings of the Korea Water Resources Association Conference
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• 2015.05a
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• pp.637-637
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• 2015

2009년 미국에서 처음으로 스마트워터그리드의 개념이 도입된 이후로 국내외 국가 기관뿐만 아니라 민간 기업에서도 스마트워터그리드에 대한 관심이 높아지고 있다. 현재 스마트워터그리드는 IBM의 진출을 시작으로 Veolia, Suez 등 다국적 물관리 기업들이 사업을 추진 중이다. 국내의 ICT기술과 수자원시스템의 융합을 통하여 용수 수요 공급량을 실시간으로 파악하고 관리하여 수자원의 지역적 시간적 격차를 해소하는 스마트워터그리드 연구가 국내에서도 진행 중이다. 물관리 시장 주도권을 확보하기 위해 글로벌 물기업간 경쟁이 심화되고 있으며, 개별플랫폼을 구축 활용하여 신규기업의 물산업 진출을 가로막고 있는 실정이다. 이러한 상황에서 국외 물산업 시장 진출을 위하여 통합플랫폼 개발 및 체계적인 데이터 구조 설계가 필요하며, 본 연구는 스마트워터그리드를 운영하기 위해 여러 곳에 분산되어 관리 운영되어지고 있는 수자원 및 물관리 데이터의 통합을 위한 체계적인 데이터베이스 구조설계에 대한 연구를 수행하였다. 이에 본 연구에서는 스마트워터그리드 도메인 내에 주력하고 있는 통합데이터베이스 구조를 외부 데이터 마이닝과 연계하여 확장하는 구조로 현실적이고 단기적인 데이터 통합효과를 위해 ETL/데이터웨어하우스방식을 적용하여 데이터 통합을 추진하였다. 지자체간 분산되어 있는 데이터베이스간의 연동은 관련 법제도 및 지자체간 협의 등 다양한 문제가 연루되어 있어 단기적으로는 B2B 데이터 연동방식을 응용하여 구성하였다. 광역 중앙 제어를 위한 통합데이터베이스는 가상DB 방식을 고려하였으며, 이는 지자체별로 구성된 통합DB에 대한 인터페이스 및 Wrapper 플랫폼을 적용하였다. 이 플랫폼간의 연동은 WaterML2.0을 적용함으로써 단기간내 구현이 가능하도록 하고 상호운용성에 문제를 해결하며, 실시간 데이터 연계를 추구하였다. 본 연구를 통해서 궁극적으로는 수자원 및 물관리 데이터의 통합을 위해 해당플랫폼에서 스키마 맵핑, 프로토콜 변환 정합 등을 실시하며, 실시간 데이터 마이닝 및 통합이 가능하도록 구성함으로써 향후 스마트워터그리드의 빅데이터 플랫폼 개발까지 확장해나갈 수 있을 것으로 기대된다.

• Database Research
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• v.34 no.3
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• pp.99-123
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• 2018

Due to the ever expanding nature of the Web, separating more valuable information from the noisy data is getting more important. Although recommendation systems are widely used for addressing the information overloading issue, their performance does not seem meaningfully improved in currently suggested approaches. Hence, to investigate the issues, this study discusses different characteristics of popular, existing recommendation approaches, and proposes a new profiling technique that uses collaborative tags and test whether it successfully compensates the limitations of the existing approaches. In addition, the study also empirically evaluates rating/tagging patterns of users in various recommendation approaches, which include the proposed approach, to learn whether those patterns can be used as effective cues for improving the recommendations accuracy. Through the sensitivity analyses, this study also suggests the potential associated with a single recommendation system that applies multiple approaches for different users or items depending upon the types and contexts of recommendations.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.24 no.12
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• pp.1682-1687
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• 2020

We study the problem of sampling a subset of nodes of graphs for bandlimited graph signals such that the signal values on the sampled nodes provide the most information in order to reconstruct the original graph signal. Instead of directly minimizing the reconstruction error, we focus on minimizing the upper bound of the reconstruction error to reduce the complexity of the selection process. We further simplify the upper bound by applying useful approximations to propose a low-weight greedy selection process that is iteratively conducted to find a suboptimal sampling set. Through the extensive experiments for various graphs, we inspect the performance of the proposed algorithm by comparing with different sampling set selection methods and show that the proposed technique runs fast while preserving a competitive reconstruction performance, yielding a practical solution to real-time applications.

• Smart Media Journal
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• v.13 no.2
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• pp.62-67
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• 2024

Due to technological advancements in viewing devices and the COVID-19 pandemic, a lot of OTT-only content is being produced and distributed as people shift from traditional movie theater viewing and broadcasters' fixed TV viewing to free-form OTT viewing using wired and wireless internet. As a result, the ability to leverage data from OTT audiences has become critical to the competitiveness of the industry. However, third parties other than OTT content providers are facing difficulties in acquiring OTT viewer data. In this paper, as a way to overcome the shortcomings of existing viewer data acquisition, we propose a method to extract audio and video data by developing an OTT viewing data acquisition agent using Web APIs by adopting a web browser environment that does not affect the performance of OS and viewing devices, so that third-party companies that need viewing data can utilize it.

• Journal of Korea Game Society
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• v.5 no.2
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• pp.19-27
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• 2005

The core price policy of on-line game marketing are FPP(Fixed Pre Paid model and PPU(Pay Per Use) model. These two models have been a on-line game company's billing system and a fundamental of MMORPG in Korea. However, they took root billing system only for first movers recently. In now, the market share of several first movers is exceeding 80%, late movers witch have same billing system cannot take part in pair competition. Even though in MMORPG, many games of late movers were favorably noticed by a lot of gamers during Evaluation. Test, a lot of companies are bankrupt before make business. Late Movers declare free game first thing, they maintain their existence and win over customers in on-line game market. And next, they guarantee item selling, give multiple experience value and game money, at last, induce their customers to pay service. As it makes trouble between pay user and free user, and it linked up with the collapse of game contents balance that designed for FPP billing system, And then meet unexpected result which reduction of game life cycle. In this Paper, we classified several contents services based on game contents, and suggested contents premium services which adopted low cost strategy lead to micro payment. we hope it will apply to late movers' new billing system in MMORPG.