• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.7A
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• pp.548-553
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• 2009

The aim of 4G mobile communication systems is to connect arbitrary devices to high-speed network anytime, anywhere. Cellular system must solve the problem of inter-cell interference caused by frequency reuse for meeting needs of 4G. In this paper, to solve interference problem we propose the algorithm, the so-called Threshold-Based Region Decision (TBRD) and analyze characteristics and performance of the proposed algorithm through simulation. The proposed technique has high applicability and flexibility due to simple construction using only existing UE measurement, and achieves performance improvement through the threshold that can be easily controlled.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.12
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• pp.6128-6134
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• 2012

In so many real estate development projects, there were strong needs to have a powerful tool to check feasibility of those projects. But there were not enough tool and measure to cover risk of real estate development and construction. Therefore I tried to find a real tool to measure investment value of development properly and efficiently, by means of case studies of many real estate development projects. Finally I found a fact that no tools of investment value analysis are perfect and efficient to hedge all kinds of risks in projects. Especially NPV(Net Present Value) and IRR(Internal Rate of Return) were not sufficient by themselves to measure investment value. So I found out that MIRR(Modified IRR), XIRR(X-IRR), ARR(Average Rate of Return), PP(Payback Period) and so on, would be supplementaries of proper and efficient investment value analysis.

• Proceedings of the Korea Contents Association Conference
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• 2009.05a
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• pp.40-44
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• 2009

Data-centric storage schemes(DCS) are one of representative researches that efficiently store and manage sensor readings in sensor nodes in the sensor networks. In DCS, a sensor sends the sensed data to a specific node in order to store them. However, it has a problem that sensor nodes consume a lot of energy for transmitting their readings to remote sensor node. In this paper, we propose a novel sensor data compression algorithm to reduce communication costs. The proposed algorithm does not transmit all the sensed data and establishes a safe region. It transmits the sensed data only when current measurement is out of the safe region, As a result, the propposed algorithm extends network life time and reduces data transmission. It is shown through performance evaluation that our proposed algorithm reduces energy consumption by about 60% over the conventional algorithm.

• Proceedings of the Korea Water Resources Association Conference
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• 2011.05a
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• pp.25-25
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• 2011

우리나라는 국토의 60% 이상이 산지로 이루어져 있다. 최근 산지하천 유역에서 발생한 홍수와 토석류 등에 의해 많은 인적 물적 피해가 발생하고 있다. 현재 산지하천 유역은 유량자료에 비해 강우관측 자료는 비교적 많이 축적되어있으며, 최근에는 레이더를 이용한 강우관측도 지속적으로 이루어져 강우특성을 분석하는 것은 용이하다. 이에 비해서 산지하천 유역의 하천 유량에 대한 자료는 부족하거나 자료가 있더라도 결측치가 많고 보유연한이 분석에 필요한 만큼 충분하지 못하다. 또한 산지하천 유역의 유출특성을 분석하기 위해서는 강우관측 자료와 수위자료로부터 환산된 유량자료가 필수적인 인자이나 산지하천 유역의 수위관측소는 설치 및 유지관리 등의 어려움으로 인하여 유량자료가 상대적으로 부족한 실정이다. 이와 같은 제약을 해소하기 위해서는 많은 비용과 시간이 소요되므로 단 시간 내에 해결하는 것은 쉬운 일이 아니다. 따라서 유역의 물리적 특성을 이용하여 임의의 지점의 설계홍수량을 손쉽고, 정확하게 산정할 수 있다면 산지유역의 홍수와 토석류에 의해 발생하는 홍수 피해에 대한 대책을 마련하는데 큰 도움이 될 것이다. 일반적인 통계적 회귀분석은 여러 분야에서 널리 적용되고 있으나, 산지하천 유역의 강우-유출해석의 경우 관측자료의 수가 적고 발생하는 사상이 애매한 경우가 많아 일반적인 통계학적 선형 회귀분석을 적용하는 데 어려움이 많다. 이와 같은 어려움을 해결하기 위해 본 연구에서는 fuzzy regression 기법을 사용하였다. Fuzzy regression 기법의 하나인 possibilistic 모형을 사용하여 주어진 관측값과 산정값의 오차를 최소화함으로써 모형의 fuzziness를 최소화하였다. fuzzy regression 기법을 사용하면 변수들 간의 애매한 관계를 쉽게 해석하고 관측값과 산정값의 오차를 최소화하여 연구목적에 적합한 결과를 도출할 수 있다. 산지유역에서 발생하는 홍수는 많은 인명 및 재산피해뿐 아니라 사회 및 경제적 측면, 환경 및 생태계 그리고 인간의 정신적인 측면까지도 깊이 영향을 미친다. 따라서 본 연구에서 제안한 fuzzy regression 기법을 사용한 홍수량 산정기법을 통해 임의 지점의 빈도별 설계홍수량을 보다 신속하고 정확하게 산정하여 수공구조물의 설계에 적용하면 집중호우에 의해 발생하는 피해를 최소할 할 수 있을 것으로 기대된다.

• Journal of KIISE:Software and Applications
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• v.32 no.9
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• pp.847-852
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• 2005

Over the last decade, numerous complexity measurement techniques for Object-Oriented (OO) software system have been proposed for managing the effects of OO codes. These techniques may be based on source code analysis such as WMC (Weighted Methods per Class) and LCOM (Lack of Cohesion in Methods). The techniques are limited to count the number of functions (C++). However. we suggested a new weighted method that checks the number of parameters, the return value and its data type. Then we addressed an effective complexity measurement technique based on the weight of class interfaces to provide guidelines for measuring the class complexity of OO codes in reverse engineering. The results of this research show that the proposed complexity measurement technique ECC(Enhanced Class Complexity) is consistent and accurate in C++ environment.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.14 no.6
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• pp.69-78
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• 2004

During the last decade, security models have been defined for two- and three-parity key exchange protocols. Currently there is a growing research interest in security models for group key management schemes. While various security models and provably secure protocols have been proposed for distributed group key exchange schemes, no results are hewn for centralized group key distribution schemes in spite of their theoretical and practical importance. We describe security requirements and a formal security model for centralized group key distribution scheme: we define the model on the channel controlled by adversaries with the ability of strong user corruption. In the security model, we propose a conversion module which can transform centralized tree-based group key distribution schemes in the literature to provably secure centralized tree-based group key distribution schemes.

• Journal of Aerospace System Engineering
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• v.11 no.3
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• pp.22-30
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• 2017

This paper examines a survey on recent research regarding health monitoring and management for liquid rocket engines (LRE). For this, we investigated precedent techniques applied to LRE development. Particularly, we focused on open-cycle LRE to apply to KSLV-II (Korea Space Launch Vehicle II). Through this study, we subdivided health monitoring algorithms and analyzed fault detection and diagnosis algorithm developed in China, since China researched open-cycle LRE that have the same cycle as KSLV-II rocket engines. We discuss significant points to be considered regarding development of the KSLV-II.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.29 no.2
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• pp.209-217
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• 2011

This study incorporate hydroacoustic sampling for bathymetry and sediment survey in Won Cheon reservoir, Suwon city, Korea. Bathymetric and sedimentation surveys were conducted using a echo sounder system and subbottom profiler in the reservoirs. Data were collected using echo sounder systems and subbottom profiler linked to a GPS, to maximize data accuracy and vessel use, and geo-referenced using a DGPS enabling the acoustic data to be used in a GIS. Echo sounder and subbottom survey data were merged within geographic information system(GIS) software to provide detailed visualization and analyses of current depths, pre-impoundment topography, distribution, thickness, and volume estimates of lacustrine sediment, and water storage capacity. These data and analyses are, necessary for development of long term management plans for these reservoirs and their watersheds.

• Journal of the Korean Institute of Landscape Architecture
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• v.45 no.4
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• pp.54-61
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• 2017

Strengthening the protection and management of very old trees is an important aspect of urban site preservation, urban design and construction. Rating various danger factors to evaluate the degree of danger posed can help to create the correct protective countermeasures. In order to develop the danger evaluation index, this study performed four round surveys by using the Delphi method and collected opinions from experts in related fields. Necessary indexes were fully added in the first and second round while the indexes falling beyond the guidelines were deleted. From the final analysis results, five areas derived a total of forty-one indicators to create a degree of danger index from vigour status, growth and development status, diseases and insect pests, soil status, and management status. The degree of danger evaluation index can provide basic data for the protection of very old trees.

• Journal of KIISE
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• v.43 no.2
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• pp.256-268
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• 2016

Modern networks consisting of various heterogeneous equipment are often installed in a distributed manner. Thus the NETCONF standard was established to manage networks centrally and efficiently. In this paper, we present a method that integrates each NETCONF layer into a single system based on the results of previous studies. In the RPC Layer, an asynchronous communication channel and parallel processes are possible using multi-threading. In the Operation Layer, operational efficiency is increased by using a data group with dependencies between the equipment configuration data and by improving the data structure, enabling efficiently processing of XML queries even with multiple managers. The data modeling techniques and grouping methods in the Content Layer are presented in detail for interoperability between the Operation Layer and the Content Layer. Finally, the GUI program was implemented and its implementation is reported. We performed an experiment comparing the improved NETCONF with the standard NETCONF to measure factors, such as query processing ratio, query processing speed, and CPU utilization. The improved NETCONF demonstrated excellent query processing ratio and query processing speed, whereas the standard NETCONF had excellent CPU utilization.