• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.2
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• pp.25-31
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• 2020

In an optical system that serves as the backbone of an information transmission system, it is essential to evaluate the statistical characteristics of the signal and noise for a performance evaluation and optimization of the system. The optical receiver system improves the reception sensitivity by adopting an optical amplifier in front of the optical detector to improve the reception sensitivity, but some problems change the bandwidth of the electronic signal to the optical signal in the optical receiver due to the ASE noise added to the output of the optical detector. The problem of changing the ratio of the bandwidth of these signals varies according to the passband characteristics of the filter present at the output stage. The frequency response effect can be solved by constructing an infinite order filter, but it is almost impossible to implement it. In this paper, the Butterworth filter was implemented to evaluate the frequency response characteristics of an optical receiver system according to the filter order. The simulation results showed that the receiver sensitivity increases as the order of Butter-Worth filters increases. In addition, as a result of simulation of the change of various values, it was confirmed that the reception sensitivity increased with increasing. That is, the average photocurrent increases, and the dispersion decreases with increasing.

• Journal of the Korea Safety Management & Science
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• v.5 no.2
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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.

• Journal of the Korean housing association
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• v.15 no.1
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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.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.12 no.19
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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.

• International conference on construction engineering and project management
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• 2009.05a
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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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• v.7 no.2
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• pp.71-92
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• 2005

Given the rapid changes in consumer tastes, technology, and competition, companies must develop a steady stream of new products and services. To be a successful product or service and explore the available market, the target market consumers need to be fully acknowledged a new product or service's value or benefit. And at the same time, the presented benefit should satisfy the customer's needs and wants. Therefore, a firm must investigate the target consumers' needs and wants before launching the new product or service. In this paper, we suggest the marketing strategy for newly developed WiBro service in telecommunication industry. We focus on consumer-oriented marketing strategy as well as the technology development process. To explore the customer's value scheme, we employ a self-explicated approach for estimating the customer's part-worth of the different target market in the process of market development stage. And we present the marketing strategy for each market development stages as well.

• Journal of the Society of Naval Architects of Korea
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• v.51 no.6
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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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• v.26 no.2
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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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• v.14 no.4
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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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• v.32 no.5
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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.