• 한국산업정보학회논문지
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• 제15권2호
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• pp.91-98
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• 2010

본 논문에서는 센서네트워크시스템에서 다양한 센서 정보를 협업시켜 주변 환경을 효율적으로 감시하는 모니터링 시스템을 제안한다. 제안한 모니터링 시스템은 카메라, 이동체 및 인체 감지센서를 설치하여 예외시간에 내부 공간으로 침입하는 침입자를 감지하기 위한 목적으로 구현이 되었다. 본 논문에서 제안한 시스템은 센위버 플랫폼 상에서 개발되었으며, 실험한 결과, 다중 센서 정보의 상호보완적 활용으로 보다 효율적인 환경을 감시가 가능함을 알 수 있었다. 또한 센위버 플랫폼의 사용으로 센서 네트워크 구성이 용이하며 다양한 센서의 추가적 설치 및 활용이 가능하다. 또한 영상정보의 분석으로 움직이는 객체에 대한 판별이 가능하게 되어 센서의 동작을 단계적으로 적용시키는 체계적인 모니터링시스템의 구현이 가능함을 보였다.

• Structural Engineering and Mechanics
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• 제49권5호
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• pp.597-618
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• 2014

For the structures containing multiple discontinuities (voids, inclusions, and cracks), the simulation technologies in the framework of extended finite element method (XFEM) are discussed in details. The level set method is used for representing the location of inner discontinuous interfaces so that the mesh does not need to align with these discontinuities. Several illustrations have been given to verify that the implemented XFEM program is effective. Then, the implemented XFEM program is used to investigate the effects of the voids, inclusions, and minor cracks on the path of major crack propagation. For a plate containing cracks and voids, two possibly crack path can be observed: i) the crack propagates into the void; ii) the crack initially curves towards the void, then, the crack reorients itself and propagates along its original orientation. For a plate with a soft inclusion, the final predicted crack paths tend to close with the inclusion, and an evident difference of crack paths can be observed with different inclusion material properties. However, for a plate with a hard inclusion, the paths tend to away from the inclusion, and a slightly difference of crack paths can only be seen with different inclusion material properties. For a plate with several minor cracks, the trend of crack paths can still be described as that the crack initially curves towards these minor cracks, and then, the crack reorients itself and propagates almost horizontally along its original orientation.

• 산업공학
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• 제21권4호
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• pp.385-393
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• 2008

Corporate's survival or bankruptcy has been determined by interaction of macroeconomic environment, industrial dynamic environment and internal process of corporate. This study attempts to examine financial factors' differences that have influence on corporate's survival or bankruptcy before and after foreign exchange crisis in Korea. The first previous empirical study that researched the cause of corporate's survival or bankruptcy in the financial ratios was attempted by Altman in 1968. Recently various survival analysis models have been published. In this paper, Multiple Discriminant Analysis model is used. We divide analytical periods into before and after foreign exchange crisis and sample randomly survival or bankruptcy firms for each period. Independent variables are financial ratios which represent growth, profitability, activity, liquidity and productivity. In conclusion, this paper examines hypothesis as "There are differences of significant financial factors before and after foreign exchange crisis."

• 산업공학
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• 제15권2호
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• pp.159-171
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• 2002

Data Warehouses integrate data from multiple heterogeneous information sources and transform them into a multidimensional representation for decision support applications. Data warehousing has emerged as one of the most powerful tools in delivering information to users. Most previous researches have focused on marketing, customer service, financing, and insurance industry. Further, relatively less research has been done on data warehouse systems in the complex manufacturing industry such as ship production, which is characterized complex product structures and production processes. In the ship production, data warehouse systems is a requisite for effective cost analysis because collecting and analysis of diverse and large of cost-related(material/production cost, productivity) data in its operational systems, was becoming increasingly cumbersome and time consuming. This paper proposes architecture of the data warehouse systems to support cost analysis in the ship production. Also, in order to illustrate the usefulness of the proposed architecture, the prototype system is designed and implemented with the object of the enterprise of producing a large-scale ship.

• Journal of Electrical Engineering and Technology
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• 제8권6호
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• pp.1431-1438
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• 2013

A pack-level battery hardware-in-the-loop simulation (B-HILS) platform is implemented. It consists of dynamic vehicle models using PSAT and multiple control interfaces including real-time 3D driving and GPS mode. In real-time 3D driving mode, user can drive a virtual vehicle using actual drive equipment such as steering wheel and accelerator to generate the cycle profile of the battery. In GPS mode, actual road traffic and terrain effects can be simulated using GPS data while the trajectory is displayed on Google map. In the latter part of the paper, several performance tests of an actual lithium-polymer battery pack are carried out utilizing the developed system. All experiments are conducted as parts of actual development process of a commercial battery pack adopting 2nd generation Prius as a target vehicle model. Through the experiments, the low temperature performance and fuel efficiency of the battery are quantitatively investigated in comparison with the original nickel-metal hydride (NiMH) pack of the Prius.

• 산업공학
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• 제24권3호
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• pp.220-230
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• 2011

The multi-reservoir operation problem for efficient utilization of water resources involves conflicting objectives, and the problem can be solved by varying weight coefficient on objective functions. Accordingly, decision makers need to choose appropriate weight coefficients balancing the trade-offs among multiple objectives. Although the appropriateness of the weight coefficients may depend on the total amount of water inflow, reservoir operating policy may not be changed to a certain degree for different hydrological conditions on inflow. Therefore, we propose to use fuzzy Data Envelopment Analysis (DEA) to rank the weight coefficients in consideration of the inflow variation. In this approach, we generate a set of Paretooptimal solutions by applying different weight coefficients on Coordinated Multi-reservoir Operating Model. Then, we rank the Pareto-optimal solutions or the corresponding weight coefficients by using Fuzzy DEA model. With the proposed approach, we can suggest the best weight coefficients that can produce the appropriate Pareto-optimal solution considering the uncertainty of inflow, whereas the general DEA model cannot pinpoint the best weight coefficients.

• 산업공학
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• 제24권3호
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• pp.231-240
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• 2011

Manufacturing enterprises have been doing their best endeavors to obtain competitiveness using various methodologies, such as information technology. In order to achieve competitiveness, they are adopting manufacturing execution system (MES). MES is a total management system that manages from the beginning of the production by product order until the quality inspection of the finished product. And MES is an inter-mediator for supplementation of information gap between ERP and inspection machine and equipment. This paper describes on establishment of effective strategy based on BPR methodology and implementation of MES small and medium PCB manufacturing company with multiple-types of products and mixed process flows. And then we proposed evaluation model based on balanced score card (BSC) for considering non-finance elements as well as finance elements. With evaluation model, we analyzed benefits and effects of MES.

• 한국통신학회논문지
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• 제31권7B호
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• pp.583-594
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• 2006

WPAN은 데이터 속도 영역, 가입자 규모, 지원되는 이동성 레벨 등의 여러 가지 요구 사항에 따라 다양한 형태로 발전되어 왔다. 또한 여러 종류의 네트워크 인터페이스를 가진 휴대 장치가 일반화되고 있다. 이러한 다중 모드 장치가 여러 종류의 WPAN 장치들과 어느 곳 어느 때든지 통신하기 위해서는 이종 무선 네트워크를 위한 프레임워크가 필요하다. 이에 본 논문에서는 이종 WPAN을 통합 할 수 있는 통합 프레임워크를 제안한다. 그리고 프레임워크의 요구사항 및 상세 설계에 대해 설명하고, 에뮬레이션 테스트 결과를 제시하였다.

• 한국광학회지
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• 제10권5호
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• pp.373-378
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• 1999

투명한 유전체 박막과 관련된 측정 분야는 반도체 산업의 발전과 함께 급속히 성장하고 있으며, 회로의 고집적화 추세에 맞추어 고정밀도의 측정 성능을 요구하고 있다. 최근 웨이퍼의 광역 평탄화를 위한 CMP(chemical mechanical polishing)공정의 도입으로 인하여 박막의 두께뿐만 아니라 미세 형상에 대한 측정 요구가 증가하고 있다. 이 논문에서는 기존의 비접촉 표면 형상 측정법의 하나인 백색광 주사 간섭법을 이용하여 박막의 두께 형상을 측정하여 새로운 측정 알고리즘 제시하고자 한다. 이 방법은 기존의 백색광 간섭 신호 해석법의 하나인 주파수 분석법과 비선형 최소 자승법을 이용함으로써 구현된다. 그리고 실험을 통하여 개발된 알고리즘의 타당성을 검증한다.

• Journal of information and communication convergence engineering
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• 제15권2호
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• pp.91-96
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• 2017

PIN-entry interfaces have high risks to leak secret values if the malicious attackers perform shoulder-surfing attacks with advanced monitoring and observation devices. To make the PIN-entry secure, many studies have considered invisible radio channels as a secure medium to deliver private information. However, the methods are also vulnerable if the malicious adversaries find a hint of secret values from user's $na{\ddot{i}}ve$ gestures. In this paper, we revisit the state-of-art radio channel based bimodal PIN-entry method and analyze the information leakage from the previous method by exploiting the sight tracking attacks. The proposed sight tracking attack technique significantly reduces the original password complexities by 93.8% after post-processing. To keep the security level strong, we introduce the advanced bimodal PIN-entry technique. The new technique delivers the secret indicator information through a secure radio channel and the smartphone screen only displays the multiple indicator options without corresponding numbers. Afterwards, the users select the target value by following the circular layout. The method completely hides the password and is secure against the advanced shoulder-surfing attacks.