• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
• /
• 2009.05a
• /
• pp.384-387
• /
• 2009

There is an increasing demand for efficient high power/weight auxiliary power supplies for use on high speed traction application. Many new conversion techniques have been proposed to reduce the voltage and current stress of switching components, and the switching losses in the traditional pulse width modulation (PWM) converter. Especially, the phase shift full bridge zero voltage switching PWM techniques are thought must desirable for many applications because this topology permits all switching devices to operate under zero voltage switching(ZVS) by using circuit parasitic components such as leakage inductance of high frequency transformer and power device junction capacitance. The proposed topology is found to have higher efficiency than conventional soft-switching converter. Also it is easily applicable to phase shift full bridge converter by applying an energy recovery snubber consisted of fast recovery diodes and capacitors.

• Journal of the Korean Wood Science and Technology
• /
• v.23 no.1
• /
• pp.13-20
• /
• 1995

This study was carried out to investigate the characterization of lignins from waste liquors in SP, KP, ASAM, and AS from Pinus densiflora, Quercus mongolica, and Betula ermanii. Spectroscopic study was applied to examine the lignins separated from different pulping process. Lignin contents in waste liqours increased in order of AS, ASAM, KP, and SP. UV spectra of three types of lignin except AS lignin showed similar pattern. IR spectra of AS lignin showed strong C=O absorptions in the range from 1730 to 1750$cm^{-1}$, where as those of KP, SP, and ASAM showed weak stretch in this region. NMR spectra of AS lignin showed strong characteristic chemical shifts of acetoxyl groups of acetylated aliphatic and aromatic hydroxyl groups at 2.0~2.5 ppm. Molecular weight of ASAM lignin from Pinus densiflora determined and found number average molecular weight 1,199, weight average molecular weight 5,458. z average molecular weight 17,242, and viscosity average molecular weight 5,457. It is considered from the results based on spectroscopic study of lignin that waste liquors (in SP, KP, ASAM and AS) from Pinus densiflora, Quercus mongolica, and Betula ermanii can be used for lignin utilization.

• The Transactions of the Korean Institute of Electrical Engineers A
• /
• v.55 no.8
• /
• pp.334-340
• /
• 2006

Copper is widely used in electric wire, cable, conductor in electric devices. As the demand for electric power is increasing rapidly, electric power devices are getting amazingly bigger and complicated. The using of light-weight conductor can reduce the size and making cost of the electric devices. In high-frequency application, Electric current in a conductor tends to shift to the surface of the conductor, resulting in an uneven current distribution in the inner conductor. In the extreme case the current may essentially concentrate in the 'skin' of the inner conductor as a surface current. In high frequency application, therefore, inner area of copper conductor may replace with aluminum conductor, which reduces the weight of conductor. This paper describes the manufacture and evaluation of composite conductors made of copper and aluminum. The optimum extruding ratio was 16 at $300^{\circ}C$. The electrical resistance of manufactured composite bus bar was $57{\mu}{\Omega}$ at DC and $49.5{\mu}\{Omega}$ at 300Hz.

• Journal of Korean Society of Industrial and Systems Engineering
• /
• v.32 no.1
• /
• pp.34-43
• /
• 2009

In this thesis, we explain developing processes of the power transmission system for lift truck. Conventional power transmission system had some problems such as spatial constraints or low speed and high torque problem. Because conventional power transmission system was mainly designed for high speed vehicles. In this paper we developed power shift drive axle specialized for $2.0{\sim}3.5$ ton lift truck. Innovative structure of transmission which is built in inside axle, enables to reduce system weight and size by 40% compared to the conventional power transmission system. Also, it is possible to do additional functions such as auto parking system and anti-roll back system.

• Kyungpook Mathematical Journal
• /
• v.56 no.3
• /
• pp.899-910
• /
• 2016

It is known that a semi-cubically hyponormal weighted shift need not satisfy the flatness property, in which equality of two weights forces all or almost all weights to be equal. So it is a natural question to describe all semi-cubically hyponormal weighted shifts $W_{\alpha}$ with first two weights equal. Let ${\alpha}$ : 1, 1, ${\sqrt{x}}$(${\sqrt{u}}$, ${\sqrt{v}}$, ${\sqrt{w}}$)^ be a backward 3-step extension of a recursively generated weight sequence with 1 < x < u < v < w and let $W_{\alpha}$ be the associated weighted shift. In this paper we characterize completely the semi-cubical hyponormal $W_{\alpha}$ satisfying the additional assumption of the positive determinant coefficient property, which result is parallel to results for quadratic hyponormality.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2000.11a
• /
• pp.317-319
• /
• 2000

We fabricated the QCM with Langmuir-Blodgett(LB) film deposited at the different subphase pH and investigated the resonant frequency response by the injection of organic gas response. In the $\pi$-A isotherms, the monolayer on the air/water interface had different limiting area per molecule and showed more condensed status as increasing the subphase pH. When palmitic acid LB film was deposited on the QCM, the resonant frequency shift was proportional to the deposited layer and had more resonant frequency shift in the case of the higher pH range as expected. In the resonant frequency for the injection of organic gas, it has been improved in the case of LB film fabricated at the lower subphase pH range and dependant upon the molecular weight of organic gas.

• Proceedings of the KSR Conference
• /
• 2008.11b
• /
• pp.321-324
• /
• 2008

Recently, there is an increasing demand for efficient high power/weight auxiliary power supplies for use on high speed traction application. many new conversion techniques have been proposed to reduce the voltage and current stress of switching components, and the switching losses in the traditional pulse width modulation(PWM) converter. Among them, the phase shift full bridge zero voltage switching PWM techniques are thought most desirable for many applications because this topology permits all switching devices to operate under zero voltage switching(ZVS) by using circuit parasitic components such as leakage inductance of high frequency transformer and power device junction capacitance. The proposed topology is found to have higher efficiency than conventional soft-switching converter. Also it is easily applicable to phase shift full bridge converter by applying an energy recovery snubber consisted of fast recovery diodes and capacitors.

• Journal of the Korean Society of Physical Medicine
• /
• v.12 no.3
• /
• pp.111-117
• /
• 2017

PURPOSE: To determine the effect of weight ball throw training as a preparatory exercise before golf practice for 8 weeks on back muscle strength, weight shifting of lower body, head speed of club, and driving distance of amateur golfers. METHODS: A total of 18 subjects were randomly assigned to the experimental group (n=9) and the control group (n=9), respectively. For the experimental group, Weight ball throw training was provided to the height of waist and shoulder similar to golf swing with the following schedule: 3 kg weight ball throw training from the first week to the 4th week; 5 kg weight ball throw training from the 5th week to the 8th week. Before and after 8 weeks of training, back muscle strength, weight shifting of lower body, head speed of club, and driving distance of subjects in the two groups were measured. RESULTS: The experimental group showed significant differences in rotational back extension torque, weight shifting of lower body, head speed of club, and driving distance during golf swing (p<.05). However, the control group only showed significant difference in driving distance during golf swing (p<.05). Back extension torque, weight shifting of lower body, and head speed of club showed significant differences between the two groups during golf swing (p<.05). CONCLUSION: Weight ball throw training can positively change rotational back muscle strength, weight shifting of lower body, head speed of club, and driving distance of amateur golfers. Therefore, it might be used as an effective warming up exercise for amateur golfers.

• Journal of the Korean Institute of Gas
• /
• v.18 no.2
• /
• pp.10-15
• /
• 2014

In this paper, the displacement and stress strength safeties have been presented for cylindrical hollow rollers of a wire saw machine. Using the finite element method, the hollow roller with Y-shaped shift and vertical columns between three tubes has been developed to analyze the displacement behavior and stress strength safeties. For the same diameter and length of hollow roller models with a different weight, the displacement behavior safety of Y-shaped shift column and vertical column models is heavily depending on the total length of a hollow roller, which is closely related to the bending moment of a hollow roller structure. But, the stress strength of a hollow roller is more influenced by the cross sectional area of a hollow roller for the similar weight. Thus, this paper recommends Y-shaped hollow roller for increasing the roller strength safety and decreasing a total roller weight.

• Research in Community and Public Health Nursing
• /
• v.17 no.2
• /
• pp.210-222
• /
• 2006

Purpose: This study was performed to identify the health status, healthy behavior, and health promotion program needs of day time and shift time industrial male workers at an workplace. Method: Relevant data were collected from June 20 to August 18, 2005. Questionaries were distributed to all subjects along with their medical records of 2005 and 151 sets of responses were used for the analysis. Collected data were analyzed using SPSS WIN 10.0. Result: 1. Health Status - day time and shift-time workers had significant differences in obesity ($x^2=8.38$, p<.01) and blood pressure ($x^2=-2.17$, p<.05). 2. Healthy Habits - Full-time and part-time workers had significant differences in regular meals (63.83, p<.01), preferred foods ($x^2=7.10$, p<.05), and sleep time (t=-3.55, p<.01). They also had significant differences in exercising ($x^2=13.11$, p<.01), exercising time (minutes) (t=-2.25, p<.01), and use of fitness centers ($x^2=7.02$, p<.05). 3. They also had significant differences in their needs of health programs ($x^2=8.66$, p<.01). Conclusion: This study revealed that day time and shift-time workers had differences in obesity and blood pressure, as well as differences in eating sleeping, and exercising patterns. Both groups needed 'fitness programs' more than any other types of health programs and picked 'weight loss' and 'stress control' programs for other options. Industrial nurses should be able to create appropriate health programs for each group based on the above results and induce the workers' active participation.