• Korea Journal of Hospital Management
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• v.21 no.1
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• pp.32-42
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• 2016

This study is conducted to estimate economic ripple effects of subsidiary services of hospitals. Using the Input/Output Analysis, this study analyzes production inducement effect, added value inducement effect, and labor inducement effect. Also, it assesses potential economic effects of the subsidiary services of which the scope is expanded as the government's proposed in 2014. Data regarding hospital subsidiary services and economic effects are obtained from the hospitals' financial statements on the National Tax Services and the Bank of Korea. The major results of this study are summarized as follows; subsidiary service profits of hospitals are 466 billion won and rent profits of hospitals are 152 billion won. Of these, the rate of subsidiary service profits in tertiary hospitals is about 66% of total subsidiary service profits. Producement inducement effect of subsidiary services of hospitals is higher than that of total industry, service industry and medical service industry. Added value inducement effect of subsidiary services of hospitals is higher than that of total industry, manufacturing industry, service industry and medical service industry. Job position inducement effect of subsidiary service in hospitals is higher than that of total industry, service industry and medical service industry. Also, employment inducement effect of subsidiary service in hospitals is higher than that of total industry and medical service industry. The results may suggest that subsidiary services revenue in medical institutions contribute to improving operating profits. Facing with intense market competition and pressures to control health care costs, hospitals may need to determine whether subsidiary services help boost their profitability and improve customer satisfaction.

• Fire Science and Engineering
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• v.29 no.5
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• pp.73-78
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• 2015

Since the hydrofluoric acid spill accident in Gumi in 2012, the current situation has continued to suffer from makeshift responses or feeble national system maintenance in preparing real countermeasures against chemical accidents, regardless of their repeated occurrence and seriousness. Industrial chemical accidents have an enormous ripple effect on the whole country and society. The purpose of this study is to propose ways of establishing directions for the national disaster management system against repeated occurrence of chemical accidents. To achieve this goal, the present study proposed improvement measures of response system for industrial chemical accident through the analysis of the current response system and structural causes of disaster control failure for chemical accidents.

• The Journal of the Korea institute of electronic communication sciences
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• v.9 no.2
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• pp.243-248
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• 2014

The permanent magnet linear synchronous motors facilitate maintenance, for it is structurally simple compare to rotating machine and has lots of advantage such as a precision control, high speed, high thrust and so on. However, it causes an increase of material cost because of structural characteristics that need to arranges the armature on the full length of transportation lines. Thus, in order to resolve this problem, we propose the discontinuous arrangement method of the armature but the edge always exists due to the structure when the armature is arranged discontinuously. Due to this edge, the cogging force is greatly generated and it causes thrust force ripple generating noise, vibration and decline of performance. Therefore, in this paper, we examined the characteristic of end edge according to the skew angle through 3-D numerical analysis using finite element method(FEM) and improved the operation characteristics.

• The Journal of the Korea institute of electronic communication sciences
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• v.8 no.8
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• pp.1241-1246
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• 2013

Currently, The general transportation system arranges the armature on the full length of transportation lines. However, when this method is applied to the long distance transportation system, it causes an increase of material cost and manufacturing time. Thus, in order to resolve this problem, discontinuous arrangement method of the armature has been proposed. However, in the method of using stationary discontinuous armatures, mover can stop in the freewheeling section which is non-installations section when disturbance is generated and the mover can not be moved because armature control is impossible. Thus, the distance determination of armature is very important. Also, when the armature is arranged discontinuously the edge always exists due to the structure. Due to this edge, the cogging force is greatly generated during the entry and ejection of the mover to the armature. This cogging force causes thrust force ripple generating noise, vibration and decline of performance, it must be reduced. Therefore, in this paper, we examined the end edge cogging force generated by the stationary discontinuous armatures through 2-D numerical analysis using finite element method (FEM) and we figured out distance of armature for end edge cogging force minimization.

• The Journal of the Acoustical Society of Korea
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• v.39 no.2
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• pp.113-119
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• 2020

Motor noise is a major concern in order to improve perceptual feeling of car interior sound due to increased motor usage in passenger cars. The purpose of this study is to propose factors that can represent the acoustic performance of motor noise according to the change of load. To this end, at first, it is shown that power spectrum and total loudness are not fit for noise performance, and then, PN_B, partial loudness related to the brush friction component, and PN_R, partial loudness related to the torque ripple component are investigated as factors representing motor noise. The performance curve of motor noise using PN_B and PN_R is proposed to identify trends of motor noise according to the loads. The curve could be a guide for the noise control, the selection of motor, and the improvement of a system.

• The Transactions of the Korean Institute of Power Electronics
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• v.8 no.3
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• pp.274-284
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• 2003

Multi-level converter that is high-capacity electric power conversion system is used widely to electric motor drive system and FATCs(Flexible AC Transmission Systems). H-Bridge converter has been prevalently applied to shunt-type system because it can be easily expanded to the multi-level. In steady states, converter is normally operated in the range of 0.7∼0.8 of modulation Index. Even though zero vectors are not imposed to high modulation index, DC-Link voltage Is constant. It means that converter has another boost vector except for zero vectors among several vectors in 3-level converter. This paper has examined the principle of boost vector and investigated the difference between another boost vector and zero vectors in 3-level converter. In addition, this paper has analysed and compared the charging currents and the capacitor voltages of two topologies. The currents and voltages are related to reference voltage. Therefore, it proposed the calculation method for the voltage ripple and the charging current of each capacitor and compared various DC-Link voltage control methods through the simulation.

• Journal of IKEEE
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• v.12 no.1
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• pp.59-64
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• 2008

In this paper, a new efficient SMPS has been designed and implemented. It can replace the existing product that is widely used in industry. To investigate the performance of the conventional SMPS, the output voltage changes due to variations in the input voltage and the load conditions, and the ripple and noise voltages have been measured and analyzed. As a result, it has been confirmed that the noise in the conventional SMPS is severe due to the deficiency of patterns for current. This is because the conventional SMPS draw out all outputs using one transformer and the alarm logic exists in the output path. To solve this problem, the switching frequency is increased from 17KHz to 70KHz and the current patterns are fully guaranteed by separating the alarm circuit and PWM circuit as a sub-board from the main board. Measurement results shows that the output noise of the designed SMPS decreases below 32% of the conventional SMPS noise for various test conditions, and both the line and load regulations are improved.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.19 no.1
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• pp.109-116
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• 2005

Wind power and photovoltaic(PV) systems are getting into the spotlight as substitute energy. But problem is happened stability by speed change of wind and the power output of the sun's ray. The power output amount according to velocity of wind power system. System breakdown can happen at change of sudden velocity, typhoon and night. This paper shows a automatic tail safety brake controller based on feedback control using wind velocity. The operation of automatic tail safety controller verified by manual test. PV system is a energy change system by temperature of sun's ray and cell. Maximum power point tracking(MPPT) is used in PV systems to maximize the photovoltaic array output power. In existed PV system is low output and changeable DC voltage for boost and filtering the buck-boost converter use. But, this paper established deformed DC-DC converter. Changed Buck-boost converter's unlined output current to line output current using DC-DC converter. This is effect that reduce ripple of output current. Proved through an output waveform comparison experiment. Finally, tail safety brake controller is established to wind turbine system for stability elevation and DC-DC converter is established on PV system for stability output.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.1
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• pp.322-328
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• 2012

This paper deals with a digital Desoldering system for removing lead-free solder. We proposed a Desoldering system that is to cope with the changed work environment of the solder materials changing from lead solder to lead-free solder, we can be quickly stable to the set temperature, and continuous operation is possible. Proposed system consists of a Desoldering station and a Desoldering gun. For the PID temperature control, we designed the 8bit MCU peripheral circuit. We had a few experiments to confirm the performance of the proposed system, and compared with the specification of same kind of imports. As a result, proposed system than the imported products showed good performance as follows: the time to reach operating temperature is 11 seconds faster, ripple temperature variation is $1.5^{\circ}C$ lower, temperature recovery rate is about $0.14^{\circ}C$/sec faster.

• Journal of Power Electronics
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• v.17 no.5
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• pp.1298-1307
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• 2017

The constant on-time current-mode controlled (COT-CMC) switching dc-dc converter is stable, with no subharmonic oscillation in its current loop when a voltage ripple in its outer voltage loop is ignored. However, when its output capacitance is small or its feedback gain is high, subharmonic oscillation may occur in a COT-CMC buck converter with a proportional-integral (PI) compensator. To investigate the subharmonic instability of COT-CMC buck converters with a PI compensator, an accurate reduced-order asynchronous-switching map model of a COT-CMC buck converter with a PI compensator is established. Based on this, the instability behaviors caused by output capacitance and feedback gain are investigated. Furthermore, an approximate instability condition is obtained and design-oriented stability boundaries in different circuit parameter spaces are yielded. The analysis results show that the instability of COT-CMC buck converters with a PI compensator is mainly affected by the output capacitance, output capacitor equivalent series resistance (ESR), feedback gain, current-sensing gain and constant on-time. The study results of this paper are helpful for the circuit parameter design of COT-CMC switching dc-dc converters. Experimental results are provided to verify the analysis results.