• 한국산학기술학회논문지
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• 제21권2호
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• pp.25-31
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• 2020

정보전송시스템의 백본 역할을 하고 있는 광시스템에서는 시스템의 성능평가 및 최적화를 위해 신호와 잡음의 통계 특성에 대한 평가가 필수적이다. 광 수신시스템에서는 수신감도를 개선하기 위해 광 검출기 전단에 광증폭기를 채용하여 수신감도를 개선하고 있으나 광 검출기의 출력부에 첨가되는 ASE 잡음으로 인해 광수신기에서 광신호에 대한 전자신호의 대역폭이 비가 변화되는 문제점 또한 존재한다. 이러한 신호들의 대역폭의 비의 변화 문제는 출력단에 존재하는 필터의 통과대역 특성에 따라 변화하게 되는데, 주파수 응답 효과는 무한대의 차수를 갖는 필터를 구성하면 해결할 수 있으나 이를 실제 구현하는 것은 거의 불가능하므로 본 논문에서는 버터 워쓰 필터를 구현하여 필터의 차수에 따른 광 수신시스템의 주파수 응답 특성을 평가하였다. 시뮬레이션 결과를 통해 Butter-Worth 필터의 차수 N이 증가하면 필터의 수신감도가 증가됨을 확인 할 수 있었다. 또한 다양한 n_sp값의 변화에 대한 시뮬레이션 결과 n_sp가 증가할수록 수신감도가 증가함을 확인할 수 있었다. 즉, n_sp에 따라 광전류의 평균치는 증가하고 분산은 감소하기 때문인 것으로 평가할 수 있다.

• 대한안전경영과학회지
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• 제5권2호
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• pp.225-238
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• 2003

This study shows that the SWOT is efficient to select a factor which is valuable as worth consideration when a decision making is necessary. Such processing of information is able to present the policy for the development of bio-industry in northern area of Kyonggi province, and create the pragmatic value and effect in carrying out the policy. The object of this study is to survey present conditions, to analyze the development of bio-industry in northern area of Kyonggi province by the decision making method of the SWOT model, to suggest a plan for the prospect of continued development field and the location of industry, and to extract fundamental data for establishment of annual action and investment plan which can develop bio-industry.

• 한국주거학회논문집
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• 제15권1호
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• pp.33-40
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• 2004

Considering the present development situation of rental apartment since 1982, the supply of rental housing for low-income dwellers has contributed a amount of quantities, but has been deficient qualities in housing policy. To propose the device of remodeling for low-income dwellers in deteriorated apartment, this study investigated the energy consumption of central heating system and the characteristics of maintenance cost in permanent rental apartment. The results of evaluation of alternative heating systems by Life Cycle Costing in permanent rental apartment were as follows; From Life Cycle 15∼20 years by Present Worth Method, the economic heating system of remodeling is central heating system (heat source: B-C oil), unit heating system(natural gas), central heating system(natural gas) in order.

• 산업경영시스템학회지
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• 제12권19호
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• pp.67-72
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• 1989

This paper concerns with the decision maker has the job of forecasting capital investments and operating expenses to aid the decision making in choosing and evaluating present annual and future alternatives. The cost estimating function eventually analysis, evaluates and choose the alternatives. And also, the marginal analysis performed originally from a preliminary design of some sort, and eventually plans are made to investigate investment possibilities. This paper provide the discounted net cash flows and the present, annual and future worth methods. In despite of any choice for an analytical methods, there remains the problems of predicting and assessments certain future events. Therefore, these models dealing with the optimal plant sizing, equipments replacement, and lease or buy will be discussed.

• 국제학술발표논문집
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• The 3th International Conference on Construction Engineering and Project Management
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• pp.425-432
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• 2009

The construction industry has been a main pillar and serves as a regulator of the Hong Kong economy. Subsequently, the fluctuations in the level of construction output can induce significant rippling effects to the economy. The Asian Financial Crisis started in 1997 and the SARS outbreak in 2003 both introduced major challenges and impacts to the Hong Kong economy and consequently the construction sector. Such decline in the importance of construction has suggested a possible structural change in the sector. It is worth investigating the driving forces behind the construction demand and see if they have changed after the heavy impacts in the past decade. The above considerations have, therefore, been the motivation of the present study to model the Hong Kong residential construction demand through multiple regression technique which can identify the significant influencing factors to the residential demand. The residential construction is studied as it constitutes a significant portion of the total construction volume. The residential sector has great influence to the general economy of Hong Kong. It is found that the underlying market structure and the driving factors for Hong Kong residential demand before and after the Asian Economic Crisis and SARS outbreak are different, suggesting that the residential construction sector or even the larger construction industry may have undergone a major structural change as Hong Kong's economy approaches maturity. It is also observed that the past literatures on construction demand are mostly focusing on predicting demand under a stable economic environment. Hence, it is worth examining if it is possible to model during economic hardship when the residential sector fluctuate dramatically under different external impacts, such as the recent global financial tsunami.

• Asia Marketing Journal
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• 제7권2호
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• pp.71-92
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• 2005

성공적인 신제품개발과 이에 따른 시장개발을 위해서는 신제품의 새로운 편익에 대해 소비자가 지각하고 있어야 하며, 이러한 편익이 소비자의 욕구를 해결해 줄 수 있어야 한다. 시장에 도입되는 신제품의 편익에 대해 새로운 가치를 부여하는 방법은 매우 다양할 수 있으나 무엇보다 새로운 가치가 소비자의 입장에서 혜택으로 여겨져야만 성공적으로 시장에 정착할 수 있다. 본 연구는 기존에 기술 중심적으로 설명되고 평가되어 왔던 와이브로 서비스를 소비자의 가치체계를 중심으로 서비스속성을 파악하고, 속성에 대한 부분가치를 추정해 이들의 상대적 중요도를 살펴보았다. 또한 부분가치를 기준으로 시장발전단계에 따른 표적고객집단을 선정하고 표적고객의 특징을 규명하는 동시에 적절한 마케팅전략을 제언하고자 한다.

• 대한조선학회논문집
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• 제51권6호
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• pp.451-458
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• 2014

The purpose of this study is to compare the economics between a diesel propulsion vessel and a LNG fuel propulsion vessel through the analysis of the present value using the LCC(Life Cycle Cost) method. This study is also to judge the economics for long-term operation of a LNG fuel propulsion vessel as a result of analysis about the equivalent uniform annual cost. In particular, LCC method was strengthened by sensitivity analysis based on combined interest rate which is considering discount rate and inflation rate simultaneously.

• Wind and Structures
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• 제26권2호
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• pp.69-74
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• 2018

Nowadays, using math logic in great civil projects is considered by the clients to achieve the goals of project including quality optimization, costs, avoiding individual, emotional and political decision making, long-term and short-term goals and they are the main requirements of each project and should be considered by the decision makers to avoid the illogical decision making applied on the majority of civil projects and this imposes great financial and spiritual costs on our country. The present study attempts to present one of the civil projects (Ghasre Shirin storage dam) whose client was not ministry of energy for the first time and the short-term and long-term goals of the private sector were applied based on the triangle of quality, cost and time. Also, the math logic and model (multi-criteria decision making method and decision making matrix) is used in one of the most important sections of project, sealing element, policies and new materials (Geosynthetics) are considered and this leads to suitable decision making in this regard. It is worth to mention that this method is used for other sections of a dam including body, water diversion system, diaphragm and other sectors or in other civil projects of building, road construction, etc.

• Journal of Information Processing Systems
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• 제14권4호
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• pp.837-850
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• 2018

Bitcoin is a decentralized crypto-currency, which is based on the peer-to-peer network, and was introduced by Satoshi Nakamoto in 2008. Bitcoin transactions are written by using a scripting language. The hash value of a transaction's script is used to identify the transaction over the network. In February 2014, a Bitcoin exchange company, Mt. Gox, claimed that they had lost hundreds of millions US dollars worth of Bitcoins in an attack known as transaction malleability. Although known about since 2011, this was the first known attack that resulted in a company loosing multi-millions of US dollars in Bitcoins. Our reason for writing this paper is to understand Bitcoin transaction malleability and to propose an efficient solution. Our solution is a softfork (i.e., it can be gradually implemented). Towards the end of the paper we present a detailed analysis of our scheme with respect to various transaction malleability-based attack scenarios to show that our simple solution can prevent future incidents involving transaction malleability from occurring. We compare our scheme with existing approaches and present an analysis regarding the computational cost and storage requirements of our proposed solution, which shows the feasibility of our proposed scheme.

• Steel and Composite Structures
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• 제32권5호
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• pp.671-686
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• 2019

Active control of solar panels with honeycomb core and carbon nanotube reinforced composite (CNTRC) facesheets for smart structures using piezoelectric patch sensor and actuator to reduce the amplitude of vibration is a lack of the previous study and it is the novelty of this research. Of active control elements are piezoelectric patches which act as sensors and actuators in many systems. Their low power consumption is worth mentioning. Thus, deriving a simple and efficient model of piezoelectric patch's elastic, electrical, and elastoelectric properties would be of much significance. In the present study, first, to reduce vibrations in composite plates reinforced by carbon nanotubes, motion equations were obtained by the extended rule of mixture. Second, to simulate the equations of the system, up to 36 mode shape vectors were considered so that the stress strain behavior of the panel and extent of displacement are thoroughly evaluated. Then, to have a more acceptable analysis, the effects of external disturbances (Aerodynamic forces) and lumped mass are investigated on the stability of the system. Finally, elastoelectric effects are examined in piezoelectric patches. The results of the present research can be used for micro-vibration suppression in satellites such as solar panels, space telescopes, and interferometers and also to optimize active control panel for various applications.