• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.16 no.10 s.101
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• pp.1003-1009
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• 2005

In this paper, small-size high-power single pole double throw(SPDT) switch with defected pound structure(DGS) is presented for wireless broadband internet application. To reduce the circuit size using slow-wave characteristic, the DGS is applied to ${\lambda}/4$ transmission line of the switch and the measured results are compared with them of conventional switch. To secure high degree of isolation, the switch with the DGS is composed of shunt-connected PIN diodes and shows insertion loss of 0.8 dB and isolation more than 50 dB at 2.3 GHz. The size of the switch is reduced about $50\%$ only with the DGS patterns while it has very similar performance to the conventional shunt-type switch.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.19 no.2
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• pp.174-180
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• 2008

The pulsed amplifier which switches the main supply voltage of RF amplifier according to input pulse signal has good efficiency and low noise level between pulses. And it has simple structure because it doesn't need a pulse modulator at input port. The pulsed amplifier using the conventional switching circuit has slow fall time compared to rise time. We proposed the novel switching circuit for improving the fall time of pulsed amplifier The proposed switching circuit is implemented by replacing FET of conventional circuit with BJT. As a result of appling this circuit to RF pulsed amplifier, the rise and fall time are 5.7 ns and 21.9 ns at 27 dBm output power, respectively.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.11 no.1
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• pp.125-133
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• 2012

This study aims at structural analysis with fatigue on the shock absorber mount of automobile. Two kinds of mount as original model 1 and reinforced model 2 are applied. Among the cases of nonuniform fatigue loads at both models, 'SAE bracket history' with the severest change of load becomes most unstable but 'Sample history' becomes most stable. In case of 'SAE bracket history' or 'SAE transmission', the maximum fatigue life at model 2 is 5 to 6 times as much as model 1 and the minimum damage at model 2 is decreased 5 to 6 times as much as model 1. In case of 'Sample history' as slow fatigue loading history, the minimum damage at model 2 becomes same as model 1 but the maximum fatigue life at model 2 is decreased more than 17 times as much as model 1. In case of 'Sample History' with the average stress of -$10^4MPa$ to $10^4MPa$ and the amplitude stress of 0MPa to $10^4MPa$, the possibility of maximum damage becomes 3%. This stress state can be shown with 5 times more than the damage possibility of 'SAE bracket history' or 'SAE transmission'. Safe and durable design of shock absorber can be effectively improved by using this study result on mount frame.

• The Journal of the Acoustical Society of Korea
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• v.15 no.5
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• pp.13-20
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• 1996

Recently, for implementation of neural networks extensive studies have been done especially VLSI technology has been regarded as the one of the most attractive means to implement neural networks. The main drawbacks of digital VLSI implementations are their large area and slow processing speed. In this paper to solve the speed and size problems we designed the efficient architecture using the binary convolution method for basic operation of neural cell, multiplication and addition. When it is used for implementing 3-layer network with 16 neural cell per layer that used neural cell based on binary convolution, clock of 50MHz and 26MCPS on 0.8${\mu}$ standard cell library has been achieved.

• Korean Journal of Optics and Photonics
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• v.12 no.1
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• pp.32-39
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• 2001

We analyze the effectiveness of the PMD compensation as a function of the link PDL, to acquire the guidelines for the successful deployment of PMDC. Result shows that the amount of BER improvement from the PMDC is decreased as the link PDL increases. Because PDL elements in the transmission system make well-defined two PSPs under the absence of PDL not orthogonal anymore, and proper definition of fast and slow polarization harder. Accordingly, consideration of PDL's potential effects must be needed for design of polarization mode dispersion compensation.sation.

• Transactions of the Korean hydrogen and new energy society
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• v.24 no.5
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• pp.461-466
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• 2013

In this research, the diesel cycle was thermodynamically interpreted to evaluate the possibility of high efficiency by converting diesel engine to the atkinson cycle, and general cycle features were analyzed after comparing these two cycles. That an experimental single cylinder and a long stroke diesel-atkinson engine, of which S/B ratio was more than 3, were manufactured. After evaluating the engine through basic experiments, a diesel engine was converted into the atkinson cycle by constituent VCR (variable compression ratio) device and VVT (variable valve timing) system. The experimental method was to observe compression work reduction effects due to low compression effects from delayed intake valve closing of the early stage atkinson engine. The result, the possibility of increasing compression ratio about each engine load was confirmation by constructing compensate expansion-compression ratio in accordance with the delayed intake valve close.

• Asian Journal of Business Environment
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• v.10 no.4
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• pp.15-19
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• 2020

Purpose: This research aims to explore the level of air pollution in Jakarta, the epicenter of COVID-19 Pandemic in Indonesia and its surrounding provinces during the first month of the Pandemic. Research design, data and methodology: This study uses data, which have been obtained real time from API (Application Programming Interfaces) of air quality website. The measurements of Air Quality Index (AQI), temperature, humidity, and other factors from several cities and regencies in Indonesia were obtained eight times a day. The data collected have been analyzed using descriptive statistics and mapped using QGIS. Results: The finding of this study indicates that The Greater Jakarta Area experienced a decrease in pollutant levels, especially in the Bogor area. Nevertheless, some areas, such as the north Jakarta, have exhibited slow reduction. Furthermore, the regions with high COVID-19 confirmed cases have experienced a decline in AQI. Conclusions: The study concludes that the air quality of three provinces, Jakarta, Banten, and West Java, especially in cities located in the Jakarta Metropolitan Area during COVID-19 pandemic and large-scale social restrictions, is getting better. However, in some regions, the reduction of pollutant concentrations requires a longer time, as it was very high before the pandemic.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.9 no.6
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• pp.1316-1322
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• 2005

Specially, though electronic commerce and electron signature technology through internet rose, PKI (Public Key Ifrastructure) is one of technologies. PKI brought several kind of new standards in encryption base technology. In spite of several kind of standardizations consist lively, shortcoming of solutions that apply PKI is expensive and slow. If main interest of encryption technology including PKI is the fast speed and security that improve, this is very serious problem. The various kinds alternatives about these problem are presented. But, we must consider about replace expense and stability etc. still. So, I propose that use suitable encryption policy by method to solve such problem. I improved some problems of existent PKI structure. Subject of this treatise designs and embody communication component could use easily and simply short message communication or simplicity way encryption communication.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.18 no.4
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• pp.934-940
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• 2014

Recently, the emergence of a variety of devices to be able to access web have brought many technological changes in the field of web development. However some web sites are still operating with a focus on computers, especially exclusive and slow developing job training related web sites which utilize a User Interface that targets only PCs. In this paper, we propose the job training management system which has a menu configuration and functions to be applied to a variety of devices, and also an applicable technologies for training students to access more easily. Finally, we evaluated its efficiency by applying the implemented system in the actual field.

• Journal of Korean Society of Forest Science
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• v.94 no.5 s.162
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• pp.307-312
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• 2005

This study aimed to develop an agroforestry technology through the participation of local people. The study was conducted in the Makiling Forest Reserve (MFR) of the University of the Philippines Los Banos (UPLB). Diagnosis and Design (D&D) methodology was employed to plan and implement effective research and development projects. Diagnostic interview and direct field observation were conducted to identify the significance of the land-use system and to understand how the system works. As a result of the diagnostic interview and direct field observation in San Vicente, old coconut-based land-use system is shifting to mahogany-based agroforestry system. One of the reasons is due to the very complicated socio-economic and silvicultural factors including lower price of coconut farm products, industry development, lack of labor force, and pest and diseases. Change in land use brought about by the shifting to mahogany-based farming system is slow. Also, mahogany trees are observed to be not well-maintained. However, mahogany based land use system gives farmers' a bigger income as well as environmental benefit. Farmer's cooperation and local forestry policy for CDM were proposed to encourage people's self-restoration effort.