• The Journal of Korean Physical Therapy
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• v.18 no.1
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• pp.75-82
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• 2006

Purpose: This study conducted the following experiment to examine transdermal permeation effects or 500 KHz ultrasound with lidocaine HCl. Methods; First, to experiment skin permeation enhancement effects of 500 KHz ultrasound frequency, it produced apparatus and transducer of 500 KHz ultrasound and Franz diffusion cell for skim permenation experiment suitable to purposes of the experiment. Transdermal permeation experiment applied Lidocaine HCL gel to skin of hairless mouse depending on ultrasound frequency and duty cycle and analyzed permeation ratio with HPLC. Results: As a result of fixing lidocaine HCl gel at the same intensity with pulsed mode and continuous mode and comparing transdermal permeation ratio by frequency, transdermal permeation ratio was increased at 500 KHz ultrasound and remarkably increased at continuous ultrasound. It was found that 1 MHz and 500 KHz ultrasound in transdermal permeation experiment enhanced transdermal permeation of lidocaine HCl. In particular, transdermal permeation of 500 KHz using lidocaine HCl gel was highest. Conclusion: However, researches considering various frequencies, intensities and application hours in low frequency areas including 500 KHz ultrasound are needed to increase deep permeation or drugs.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.02a
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• pp.472-472
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• 2011

The capacitive coupled plasma (CCP) has been extensively used in the semiconductor industry because it has not only good uniformity, but also low electron temperature. But CCP source has some problems, such as difficulty in varying the ion bombardment energy separately, low plasma density, and high processing pressure, etc. In this reason, dual frequency CCP has been investigated with a separate substrate biasing to control the plasma parameters and to obtain high etch rate with high etch selectivity. Especially, in this study, we studied on the etching of $SiO_2$ by using the pulse-time modulation in the dual-frequency CCP source composed of 60 MHz/ 2 MHz rf power. By using the combination of high /low rf powers, the differences in the gas dissociation, plasma density, and etch characteristics were investigated. Also, as the size of the semiconductor device is decreased to nano-scale, the etching of contact hole which has nano-scale higher aspect ratio is required. For the nano-scale contact hole etching by using continuous plasma, several etch problems such as bowing, sidewall taper, twist, mask faceting, erosion, distortions etc. occurs. To resolve these problems, etching in low process pressure, more sidewall passivation by using fluorocarbon-based plasma with high carbon ratio, low temperature processing, charge effect breaking, power modulation are needed. Therefore, in this study, to resolve these problems, we used the pulse-time modulated dual-frequency CCP system. Pulse plasma is generated by periodical turning the RF power On and Off state. We measured the etch rate, etch selectivity and etch profile by using a step profilometer and SEM. Also the X-ray photoelectron spectroscopic analysis on the surfaces etched by different duty ratio conditions correlate with the results above.

• Transactions on Electrical and Electronic Materials
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• v.12 no.6
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• pp.262-266
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• 2011

A simulation study of a current-mode direct current (DC)-DC boost converter is presented in this paper. This converter, with a fully-integrated power module, is implemented by using bipolar complementary metal-oxide semiconductor (BiCMOS) technology. The current-sensing circuit has an op-amp to achieve high accuracy. With the sense metal-oxide semiconductor field-effect transistor (MOSFET) in the current sensor, the sensed inductor current with the internal ramp signal can be used for feedback control. In addition, BiCMOS technology is applied to the converter, for accurate current sensing and low power consumption. The DC-DC converter is designed with a standard 0.35 ${\mu}m$ BiCMOS process. The off-chip inductor-capacitor (LC) filter is operated with an inductance of 1 mH and a capacitance of 12.5 nF. Simulation results show the high performance of the current-sensing circuit and the validity of the BiCMOS converter. The output voltage is found to be 4.1 V with a ripple ratio of 1.5% at the duty ratio of 0.3. The sensing current is measured to be within 1 mA and follows to fit the order of the aspect ratio, between sensing and power FET.

• Journal of agriculture & life science
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• v.50 no.2
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• pp.187-194
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• 2016

The purpose of this study was to analyze temperature distribution characteristics using a model swine housing for temperature sensor adjustable positioning and developed a sensor and controller embedded exhaust fans utilizing ICT fusion technology for windowless swine housing. Temperature measured by the sensor attached on the exhaust fan was also determined that there is no problem, the temperature is located in the upper fan given the measured errors shown in the 1℃ temperature difference between the lower temperature than the other positions in the model swine housing. The performance of the exhaust fan at maximum output was found to be 1920rpm, air flow rate 125㎥/min. When the open area ratio of 70% one proper air volume of the exhaust fan was found to be 75㎥/min, 60pa. Maximum efficiency in all of the output of the exhaust fan is exhibited at about 70% open area ratio of the damper. The number of revolution of the exhaust fan was 1920rpm when the output was a maximum of 100%. AC output phase of the pulse duty ratio change of the controller was shown to change without delay. It was determined that the instant fan speed control is possible.

• Magazine of the Korean Society of Agricultural Engineers
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• v.11 no.1
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• pp.1561-1579
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• 1969

In Korea, the duty of water in paddy fields was measured at the Agricultural Experimental Station in Suwon about 60 years ago. After that time some testing has been made in several places, but the key points in its experiment were the water depth of evapo-transpiration. Improved breeds, progress in cultivation and management techniques as well as development of measuring apparatus in recent years have necessitated the review of the duty of water in paddy fields. The necessity of reviewing the conventional methods has become even more important, as no source of information has been made available through survey of water utilization on a soil use basis which requires data on peculiar features of the water depth of evapo-transpiration. For example, the duty of water in paddy field is largely affected by the water depth of evapo-transpiration in connection with the wetted paddy field, whereas in connection with the normal paddy fields without this characteristic the vertical percolation become the predominant factor in measuring the decreasing depth of water. Therefore, it becomes important. that not only the water depth of evapotranspiration but also the vertical percolation process should also be observed in order to arrive at a realistic conclusion. As the vertical percolation has aclose relationship to the height of the underground water, the change of the latter can be measured. As the conclusion of this experiment, the following subjects are indicated. 1. In order to determine the economic duty of water in paddy fields on a basis of varying soil features, the varying soil features in the benifited area should be investigated thoroughly. The water depths of evapo-transpiration(ET) ratio to evaporation in the evaporator(V) on a basis of the varying soil features are as follows: clay loam ET/V = 1.11, loam ET/V = 1.64, sandy loam ET.V = 1.63 2. The decreasing depth of water consists of the water depth of evapotranspiration, the vertical per colation and the percolation of foot path. Among these three, the percolation of foot path can be utilized again. 3. As the result of this experiment, it shows the decreasing depth of water as follows. clay loam 9.3 mm/day, loam 13.5mm/daty, sandy loam 15.3mm/day 4. On a basis of the varying soil features and the height of the underground water, the vertical percolation varies. 5. The change of the vertical percolation on a basis of the varying soil features shows as follows: clay loam $1{\sim}2$ mm/day, loam $2{\sim}3$mm/day, sandy loam $3{\sim}4$mm/day 6. The level of the underground water changes sensibly by priority of clay loam, loam, sandy loam. When it rains, the level of the underground water rises fast and falls down slowly. 7. The level of the underground water changes within the scope of 25cm 8. The transpiration ratio is given in table 8 and their value are as follows: clay loam 168.8, loam 255.6, sandy loam 272.5

• Journal of agricultural medicine and community health
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• v.38 no.4
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• pp.229-242
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• 2013

Objectives: The objective of this study was to identify the influence of shift work on sleep quality, daytime sleepiness, and perceived errors during nursing work among hospital nurses. Methods: The study subjects were 209 hospital nurses working in two general hospitals in South Korea. The data were collected through self-administered questionnaires in May 2013. Sleep quality was measured using Korea Pittsburgh Sleep Quality Index (PSQI-K), daytime sleepiness was measured using Epworth Sleepiness Scale (ESS), and perceived errors in past 6 months during nursing duty hours with the tool developed in this study. Results: The sleep quality was significantly worse among rotating shift nurses when compared to fixed day duty nurses. However, the odds ratio (OR) of 1.92 [95% confidence interval(CI): 0.58-6.37] adjusted for sociodemographic variables, health behaviors, and working environment in logistic regression was not significant. There was no significant difference in the daytime sleepiness between rotating shift nurses and fixed day duty nurses in both simple and multivariable analyses. There were significantly more perceived errors in rotating shift nurses than fixed day duty nurses. However, the OR of 1.26 (95% CI: 0.38-4.21) adjusted for sociodemographic variables, health behaviors, working environment, sleep quality, and daytime sleepiness in logistic regression was not significant. Depression (OR=3.31, 95% CI: 1.11-9.84) and daytime sleepiness(OR=1.18, 95% CI: 1.07-1.30) were significantly associated with perceived errors in logistic regression. Conclusion: This study suggested shift work among hospital nurses had no independent influence of sleep quality, daytime sleepiness, and perceived errors. However, daytime sleepiness had independent influence of perceived errors. More studies are warranted to achieve more reliable conclusion.

• The Transactions of the Korean Institute of Power Electronics
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• v.7 no.2
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• pp.194-204
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• 2002

In this paper, a new two-phase space vector RPWM(Random PWM) is proposed. In the proposed RPWM, each of two-phase PWM pulses is located randomly in each switching interval. Based on the space vector modulation technique, the duty ratio of the pulses is calculated. Along with the randomization of the PWM pulses, we can obtain the effects of spread spectra of inverter output voltage, d.c link current and audible switching acoustic noise as in the case of randomly changed switching frequency. To verily the validity of the proposed two-phase RPWM scheme, the experiment based on the Cl67 micro-controller was executed. The performance of the proposed scheme was compared with traditional PWM schemes experimentally.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.37 no.4
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• pp.399-405
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• 2009

The focal plane image stabilization for a satellite camera is one of the an effective method which can increase the satellite camera's image quality by removing the motion disturbance of a focal plane. The objectives of this article are to introduce the concept of the focal plane image stabilization and determine the best driving conditions of the actuator for the response and thrust. Under various driving condition the experiments have been performed to investigate the response and thrust characteristics of the piezoelectric driven stick-slip actuator of the focal plane image stabilizing device. From experiments, the best driving frequency and duty ratio for the magnesium slider are 70 kHz and 27%, respectively.

• Journal of ILASS-Korea
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• v.17 no.4
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• pp.185-191
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• 2012

Particulate matters (PM) that is generated by most diesel engine is regulated by the mass concentration measured by the conventional method it had been. Recently, Europe PMP (Particle Measurement Program) decided to start the regulation of vehicle's nano-sized particle number (PN) from the year of 2011 because of nano-particle's higher degree of harm to the human body. So firstly, the standard level of PN emission is introduced in the Euro 5/6 emissions regulation with a limit of $6{\times}10^{11}$ per km for light duty vehicle. Also KPMP(Korea Particle Measurement Program) was organized to copy quickly international technical trend. In this paper, it was investigated the nano-sized PN measurement characteristics for different particle generators between spray type and soot type. And the difference ratio between particle generators, the characteristic of PN concentration, counting efficiency and linearity was analyzed. Then, we make conclusions as followed. When particle diameter is increased, counting efficiency of two generators is decreased. Also Secondary calibration method is more higher 3% than Primary calibration method. Finally, SOF which is included in soot particles is not totally removed so it have great influence on test result of counting efficiency and linearity.

• Journal of the Ergonomics Society of Korea
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• v.36 no.2
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• pp.157-168
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• 2017

Objective: This study aims to understand the motorcycle accident characteristics of food delivery workers and to present basic guidelines on accident prevention through accident. Background: It is known that food delivery workers have a high ratio of self-employed and youth workers, and occupations with frequent disasters. Therefore the occupation is known to really be in need of accident prevention policy. Method: This study analyzed the data of motorcycle crashes of 1,310 food delivery workers that have been approved as on-duty industrial crashes since 2015. The accident characteristics were examined by dividing them into driver related factors and accident related factors. Results: Among the motorcycle crashes of food delivery workers, 99.2% of the victims were males, 82.6% had less than six months of work experience. 76.2% of the victims were employed by the companies with less than five workers. In addition, there was a difference in accident characteristics according to age, type of cuisine, accident time of the day, injured organs and injured body part. Conclusion: The results of this study can be used as baseline data to devise systematic measures to prevent motorcycle crashes of food delivery workers. Application: Preventative measures for novice young part time workers including safety education/training need to be established.