• Journal of the Korean Society for Precision Engineering
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• v.30 no.11
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• pp.1187-1192
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• 2013

In the case of 4 wheel drive (4-WD) type car, power switching occurs to 4-WD by operating lever or switch that operates power switching device attached in transfer case which can operate motor by electric signal. So if the RPM of motor is high, power switching will not exactly occur and can cause damage to gear in transfer case according to circumstances. So in this study, we applied 2 level of planet gear type motor spindle of motor drive part of a power train. And conducted decelerating to increase torque to switch power safe and accurately. Also, we researched efficiency of gear by designing reduction gear ratio and gear type and by calculating contact stress and bending strength. Based on researched content, we made drive head of power switching device and a reduction module which uses type that uses motor spindle as sun gear and ring gear as cover.

• Journal of the Korean Society for Precision Engineering
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• v.19 no.9
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• pp.172-178
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• 2002

One of the ever-increasing demands on the performances of heterodyne interferometers is to improve the measurement resolution, of which current state -of-the-art reaches the region of sub-nanometers. So far, the demand has been met by increasing the clock speed that drives the electronics involved fur the phase measurement of the Doppler shift, but its further advance is being hampered by the technological limit of modem electronics. To cope with the problem, in this investigation, we propose a new scheme of phase -measuring electronics that reduces the measurement resolution without further increase in clock speed. Our scheme adopts a super-heterodyne technique that lowers the original beat frequency to a level of 1 MHz by mixing it with a stable reference signal generated from a special phase- locked-loop. The technique enables us to measure the phase of Doppler shift with a resolution of 1.58 nanometer at a sampling rate of 1 MHz. To avoid the undesirable decrease in the maximum measurable speed caused by the lowered beat frequency, a special form of frequency up-down counting technique is combined with the super-heterodyning. This allows performing required phase unwrapping simply by using programmable digital gates without 2n ambiguities up to the maximum velocity guaranteed by the original beat frequency.

• The Journal of Asian Finance, Economics and Business
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• v.5 no.1
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• pp.5-9
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• 2018

Many developing countries have attempted to depreciate their currencies in order to make their products cheaper, stimulate exports, shift aggregate demand to the right, and increase aggregate output. However, currency depreciation tends to increase import prices, raise domestic inflation, reduce capital inflows, and shift aggregate supply to the left. The net impact is unclear. The paper incorporates the monetary policy function in the model, which is determined by the inflation gap, the output gap, the real effective exchange rate, and the world real interest rate. Applying an extended IS-MP-AS model (Romer, 2000), the paper finds that real depreciation raised real GDP during 1997.Q1-2005.Q3 whereas real appreciation increased real GDP during 2005.Q4-2017.Q2. In addition, a higher government debt-to-GDP ratio, a lower U.S. real federal funds rate, a higher real stock price, a lower real oil price or a lower expected inflation rate would help increase real GDP. Hence, real depreciation or real appreciation may increase or reduce aggregate output, depending upon the level of economic development. Although expansionary fiscal policy is effective in stimulating the economy, caution needs to be exercised as there may be a debt threshold beyond which a further increase in the debt-to-GDO ratio would hurt economic growth.

• Journal of Agricultural Extension & Community Development
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• v.7 no.2
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• pp.279-288
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• 2000

Agricultural extension services in Korea are faced with increasing demands for more efficient production and managerial technology according to globalization and free trade system. At the same time, three steps of organizational restructuring in 1998 and 1999 resulted in decreased number of organization and manpower, thus, resulting confusion in implementing extension services. To cope with the international and national challenges, Korean agricultural extension services should try paradigm shift including the followings; 1. To establish identity of agricultural extension services in Korea through making laws and regulations in terms of concept, roles, principles. implementation and methods. 2. To implement vitalizations plan through enhancement of national extension service such as food production. raising local specialty products for domestic consumption and producing strategic agricultural products for export. expanding capability of rural women, increasing opportunity for management consultation, supporting digital technology information, and promoting morale and capability of extension educators. 3. To reform agricultural extension system through adjusting the functions of extension service of the Rural Development Administration, regionalizing city and county extension center to provincial level, and changing the status of directors of extension centers from city /county to national government.

• YAKHAK HOEJI
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• v.54 no.1
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• pp.13-21
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• 2010

The interaction of cadmium (II) ion with quercetin, qurecitrin and (+)-catechin was investigated in aqueous solution at various pH. The flavonoid/cadmium stochiometries for cadmium (II) binding to flavonoid have been determined by UV-visible spectroscopy. 1:1 Cd(II)-Flavonoid complex had a maximum absorbance and showed the bathochromic shift of the long-wavelength band of the UV-vis spectra in the alkaline pH, that occurs upon complexation, is due to a ligand-tometal charge transfer. The optimal concentration of Cd(II)-flavonoid complexes showed that complexation reaction could be classified in the following way: 55.27 ${\mu}M$ catechin > 54.72 ${\mu}M$ quercetin > 53.52 ${\mu}M$ quercitrin at the chelating site level. These results suggest that Cd(II)-flavonoid complex has the optimal condition of chelation in 0.2 M $NH_3$ - 0.2 M $NH_4Cl$ (pH 8.0) solution.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.67 no.9
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• pp.1152-1158
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• 2018

In this paper, Optimal operation plan through load analysis of industrial end-user is suggested. It calculated economic feasibility of ESS with detailed power lad analysis and conditions. Generally, if the latest maximum power is less than 30% of contracted power, it can not be peak shaving operation plan. and if the peak load level stays stead for 24 hours, it is difficult peak shaving for ESS. In addition to, When the peak load is occurred in summer or winter, a hybrid operation method combining the peak shaving plan and the time shift method is proposed. Therefore, When ESS is installed in industrial electrical customer, it is achieved best effect through the optimal operation plan.

• Proceedings of the Korean Nuclear Society Conference
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• 1996.05a
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• pp.471-476
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• 1996

In this study, the method to use the phase shift keying (PSK) communication technique in smart transmitter is presented. In nuclear applications. smart transmitters for various parameters are expected to improve the accuracy of measurement and to reduce the load of calibration work. The capability of communication in field level is the most important merit of the smart transmitter. The most popular method is using of digital and analog techniques simultaneously - transmitting measurements from the field at 4∼20mA while modulating the current to carry digital information in both directions over the same twisted pairs. Conventional smart transmitters use the frequency shift keying (FSK) method for digital communication. Generally, however, the FSK method has the speed limit at 1200 bps. Amount of information to transmit becomes increasing as the processing technique is improved. The PSK method is noticeable alternative for high speed digital communication, but it has non-zero DC component. In order to use the PSK method in the field transmission with smart transmitter, the method to remove the DC component is studied in this work.

• Safety and Health at Work
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• v.13 no.1
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• pp.3-8
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• 2022

Background: This study aims to allow the development of efficient measures to improve occupational health of shift-working nurses focusing on job stress, health promotion behavior, resilience, and sleep disturbance. Methods: It was conducted on a subject panel of 137 nurses who were aware of the purpose of the study and agreed to participate. They worked three shifts at a tertiary hospital or a general hospital located in metropolitan city B. The collected data were analyzed by the independent t test and one-way analysis of variance and post-tested by Scheffe's test, Pearson's correlation coefficients, and multiple linear regression analysis using SPSS/WIN 25.0. Results: The significant influencing factors on sleep disturbance were of those whose subjective health status was 'normal' (b = 0.29, p < .001), 'not healthy' (β = .40, p < .001), who have job stress (β = .22, p = .003), and who have health promotion behavior (β = -0.17, p = .023). The overall explanatory power was 31.1% (F = 16.31, p < .001). Conclusion: Through this study, nurses' subjective health status and job stress of working shifts were found to be important factors influencing the sleep disturbance level, and the most influencing factor was identified as the subjective health status.

• ETRI Journal
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• v.45 no.1
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• pp.163-170
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• 2023

We report an electroabsorption modulator (EAM)-integrated distributed Bragg reflector laser diode (DBR-LD) capable of supporting a high data rate and a wide wavelength tuning. The DBR-LD contains two tuning elements, plasma and heater tunings, both of which are implemented in the DBR section, which have blue-shift and red-shift in the Bragg wavelength through a current injection, respectively. The light created from the DBR-LD is intensity-modulated through the EAM voltage, which is integrated monolithically with the DBRLD using a butt-joint coupling method. The fabricated chip shows a threshold current of approximately 8 mA, tuning range of greater than 30 nm, and static extinction ratio of higher than 20 dB while maintaining a side mode suppression ratio of greater than 40 dB under a window of 1550 nm. To evaluate its modulation properties, the chip was bonded onto a mount including a radiofrequency line and a load resistor showing clear eye openings at data rates of 25 Gb/s nonreturn-to-zero and 50 Gb/s pulse amplitude modulation 4-level, respectively.

• Transactions on Electrical and Electronic Materials
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• v.17 no.5
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• pp.280-288
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• 2016

Microelectronic product consumers may already be expecting another paradigm shift with smarter phones over smart phones, but the current status of microelectronic manufacturing engineering education (MMEE) in universities hardly makes up the pace for such a fast moving technology paradigm shift. The purpose of MMEE is to educate four-year university graduates to work in the microelectronics industry with up-to-date knowledge and self-motivation. In this paper, we present a comprehensive curriculum for a four-year university degree program in the area of microelectronics manufacturing. Three hands-on experienced-based courses are proposed, along with a methodology for undergraduate students to acquire hands-on experience, towards integrated circuits (ICs) design, fabrication and packaging, are presented in consideration of manufacturing engineering education. Semiconductor device and circuit design course for junior level is designed to cover how designed circuits progress to micro-fabrication by practicing full customization of the layout of digital circuits. Hands-on experienced-based semiconductor fabrication courses are composed to enhance students’ motivation to participate in self-motivated semiconductor fab activities by performing a series of collaborations. Finally, the Microelectronics Packaging course provides greater possibilities of mastered skillsets in the area of microelectronics manufacturing with the fabrication of printed circuit boards (PCBs) and board level assembly for microprocessor applications. The evaluation of the presented comprehensive curriculum was performed with a students’ survey. All the students responded with “Strongly Agree” or “Agree” for the manufacturing related courses. Through the development and application of the presented curriculum for the past six years, we are convinced that students’ confidence in obtaining their desired jobs or choosing higher degrees in the area of microelectronics manufacturing was increased. We confirmed that the hypothesis on the inclusion of handson experience-based courses for MMEE is beneficial to enhancing the motivation for learning.