• JSTS:Journal of Semiconductor Technology and Science
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• v.7 no.3
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• pp.166-176
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• 2007

Radio frequency (RF) microelectromechanical systems (MEMS) have been pursued for more than a decade as a solution of high-performance on-chip fixed, tunable and reconfigurable circuits. This paper reviews our research work on RF MEMS switches and switching circuits in the past five years. The research work first concentrates on the development of lateral DC-contact switches and capacitive shunt switches. Low insertion loss, high isolation and wide frequency band have been achieved for the two types of switches; then the switches have been integrated with transmission lines to achieve different switching circuits, such as single-pole-multi-throw (SPMT) switching circuits, tunable band-pass filter, tunable band-stop filter and reconfigurable filter circuits. Substrate transfer process and surface planarization process are used to fabricate the above mentioned devices and circuits. The advantages of these two fabrication processes provide great flexibility in developing different types of RF MEMS switches and circuits. The ultimate target is to produce more powerful and sophisticated wireless appliances operating in handsets, base stations, and satellites with low power consumption and cost.

• Smart Structures and Systems
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• v.15 no.3
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• pp.807-830
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• 2015

When a building structure requires both health monitoring system and vibration control system, integrating the two systems together will be cost-effective and beneficial for creating a smart building structure with its own sensors (nervous system), processors (brain system), and actuators (muscular system). This paper presents a real-time integrated procedure to demonstrate how health monitoring and vibration control can be integrated in real time to accurately identify time-varying structural parameters and unknown excitations on one hand, and to optimally mitigate excessive vibration of the building structure on the other hand. The basic equations for the identification of time-varying structural parameters and unknown excitations of a semi-active damper-controlled building structure are first presented. The basic equations for semi-active vibration control of the building structure with time-varying structural parameters and unknown excitations are then put forward. The numerical algorithm is finally followed to show how the identification and the control can be performed simultaneously. The results from the numerical investigation of an example building demonstrate that the proposed method is feasible and accurate.

• The Journal of the Korea institute of electronic communication sciences
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• v.15 no.4
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• pp.617-624
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• 2020

Due to the rapid development of science technology and the main characteristics of the defense industry, such as long development period, design complexity, high possibility of discontinuing parts due to long life cycle, and small quantity production, it can cause increasing of the inflow possibility of counterfeit electronic parts and deteriorating the reliability of weapons systems. This paper presents the specific criteria for the identification of electronic parts to be verified for mass produced weapons systems after the development is completed, and the identification and verification methods for the inflow of counterfeit electronic components.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2009.10a
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• pp.185-186
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• 2009

According to increase of container transportation, demands of empty container handling has been increasing, so research of empty container has been studied steadily. However, the handling of containers and empty containers is not handled simultaneously. Moreover, as Korean ICD(Inland Container Depot) and ODCY(Off-Dock Container Yard), the inland depot in many environments, relocation research due to demand of empty container has not been studied sufficiently. This paper formulates and analyzes logical mathematical relocation model according to demands of empty container which are required in container terminal, ICD, and ODCY as cargo depots. This paper also aims to help reduce cost by improving q current empty container relocation as same as the past procedure.

• Journal of the Korean Society of Safety
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• v.11 no.1
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• pp.99-107
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• 1996

This survey is to compare the the number of accidents which were occurred in 24 construction companies with the average accident in construction industry. The number of accidents in 24 companiesis is lower than the average accident, then it is classified "save", otherwise it is classified "loss". This survey is conducted to have top management be interested and invest for safety by recognizing that safety management could be profit for the company. The result of this survey is as follows : The total save amount in 1992 is 44,780mi11ion Won and average is 1,870mi11ion Won, with being 11, 200mi11ion Won by reduction amount of deaths and 33,580mi11ion Won by reduction amount of injuries. In 1993 the total is 33,330mi11ion Won and average is 1,390mi11ion Won, and in 1994 the total is 38, 720mi11ion Won and the average is 1,610mi11ion Won. This result is save amount of workmen's compensation insurance with excluding the indirect costs for accidents. The company which ranked the highest save amount is B Construction Company with being 15.1 billion Won and the next is A Construction Company during 3 years. The Company which ranked highest percentage of save amount to sales amount is Q Heavy industry with being 0.359% and the next is B Construction Company during 3 years.pany during 3 years.

• Journal of the Korean Society for Precision Engineering
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• v.13 no.3
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• pp.26-30
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• 1996

The successful development of the automobile industry in Korea is the firstfruit of the epochmaking automobile policy in 1973: Top-Down mass production of Korean model cars. In Top-Down system, indigenous model, which is the most important and difficult part of the automobile industry, is devised first, followed by the mass production of the major parts, such as bodies, engines, etc. This system is in contrast to the prevailing Bottom-up system in the third-world, which assembles automobiles by gradually adding up simple domestic parts. The Government, faced with a vicious circle of depen- dence on assembly of foreign cars, high prices, small demand and low production, decided it was time to move to the mass production of the indigenous models. It was hoped that the efficiencies of low cost Korean models would be epochally improved by overcoming the sway of foreign models and by strengthening the production capabilities of the main parts. In contrast to these develop- ment planning, assembled vehicles numbered only 26,300 units in 1973. In the year of 1995, the total number of automobile production have already passed 2,534,000. As steady growth in worldwide demand is forecast, Korea will able to play a major role as an important automobile maker of the next century.

• Progress in Superconductivity and Cryogenics
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• v.23 no.4
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• pp.44-48
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• 2021

In order to obtain ultra-high resolution MRI images, research and development of 11 T or higher superconducting magnets have been actively conducted in the world, recently. The high-temperature superconductor (HTS), first discovered in 1986, was very limited in industrial application until mid-2010, despite its high critical current characteristics in the high magnetic field compared to the low-temperature superconductor. This is because HTS magnets were unable to operate stably due to the thermal damage when a quench occurred. With the introduction of no-insulation (NI) HTS magnet winding technology that does not burn electrically, it could be expected that the HTS magnets are dramatically reduced in weight, volume, and cost. In this paper, a 6 T-class NI HTS magnet for basic characteristic analysis was designed, and a distributed equivalent circuit model of the NI coils was configured to analyze the charging current characteristics caused by excitation current, and the charge delay phenomenon and loss were predicted through the development of a simulation model. Additionally, the critical current of the NI HTS magnets was estimated, considering the magnetic field, its angle and temperature with a given current. The loss due to charging delay characteristics was analyzed and the result was shown. It is meaningful to obtain detailed operation technology to secure a stable operation protocol for a 6T NI HTS magnet which is actually manufactured.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.18 no.2
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• pp.75-84
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• 2008

Recently, the straightforward CRT-RSA was shown to be broken by fault attacks through many experimental results. In this paper, we analyze the fault attacks against CRT-RSA and their countermeasures, and then propose a new fault infective method resistant to the various fault attacks on CRT-RSA. In our CRT-RSA algorithm, if an error is injected in exponentiation with modulo p or q, then the error is spreaded by fault infective computation in CRT recombination operation. Our countermeasure doesn't have extra error detection procedure based on decision tests and doesn't use public parameter such as e. Also, the computational cost is effective compared to the previous secure countermeasures.

• The Journal of Asian Finance, Economics and Business
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• v.8 no.3
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• pp.1241-1248
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• 2021

This study employs data from CRSP/Compustat files for the period from 2003 to 2017 and applies a panel data analysis. The results of this study show a positive relationship between trade credit and the firm's market value, however, the results show a negative relationship if we test the impact of financial credit on the firm's market value. The results have direct policy implications for investors, the firm's management, and financial strategy. An implication of our study is that using trade credit as a source of financing may give a positive signal of the firm's creditworthiness and increase the firm's market value. Also, the results of our study indicate that the benefits of using trade credit may outperform the cost of using it as a source of finance. Prior studies examine the impact of financial leverage on the firm's value, however, this study contributes to the existing studies that examine the factors that affect the firm's market value by examining the impact of using trade credit finance on the firm's market value. The main limitation of this study is that the results are based on listed firms, using data from unlisted firms is not available.

• Asian Journal of Business Environment
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• v.12 no.4
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• pp.35-44
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• 2022

Purpose: The main purpose of this study is to find out the impact of ownership structure on firm performance in the pharmaceutical and chemical industry of Bangladesh. Research design, data and methodology: The study has been conducted on 28 listed pharmaceutical and chemical companies from 2012 to 2020. Return on Assets (ROA) and Tobin's Q are selected as indicators of internal and market performance of the firms respectively whereas institutional ownership, directors' ownership and foreign ownership are selected as proxies of ownership structure. Panel analysis using random effects, lag method and time dummy method is used to analyse the relationship. Results: The study has found the existence of highly concentrated directors' ownership, a low percentage of institutional ownership and a very insignificant proportion of foreign ownership in the industry. The regression results show that directors' ownership has a positive and significant impact on firm performance, supporting the concept of agency theory. The study has also found a positive and significant impact of foreign ownership on firm performance. Unfortunately, the impact of institutional ownership is found to be insignificant. Conclusions: Directors' ownership and foreign ownership decreases agency cost that ultimately increases firm performance. However, the role of institutional investors is not significant enough to improve firm performance. It is suggested that institutional investors should be more active and involved in monitoring the activities of the organisations to improve performance.