• Journal of the Korean Geographical Society
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• v.28 no.4
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• pp.356-378
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• 1993

This study examines the competitiveness of urban industrial structure and its changing characteristics. Cluster analysis of Arizona towns based on economic functions revealed the changing characteristics of urban functions over time. The relationship between the changes of urban functions and industrial competitiveness was confirmed through shift-share analysis. The level of industrial specialization has become more closely related to urban size in terms of both population and employment, but the relationship between metropolitan location and specialization level is not clear. Also, it is validated that the economies of Arizona towns have become more diversified and, consequently, have tended to converge toward the state average in industrial structure over time.

• Korean Journal of Culture and Social Issue
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• v.29 no.4
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• pp.637-655
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• 2023

Community psychology, which originated from the United States, has made significant progress in many countries over the past 50 years, but it is still an unfamiliar field in Korea. The purpose of this paper is to introduce the core concepts of community psychology and to increase the understanding of community psychology and highlight its practicality and importance. This paper introduces the core concepts of community psychology, including a shift in perspective, first-order and second-order change, ecological level of analysis, and action. It also considers how these core concepts can be utilized and which direction they can provide for the Korean society. Ultimately, the goal is to promote public awareness of community psychology, expand the scope of psychology in Korea, and make a positive contribution to solve social issues in the Koream society.

• Journal of Power Electronics
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• v.15 no.3
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• pp.652-659
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• 2015

This paper presents a new hybrid soft switching dc-dc converter with a low circulating current and high circuit efficiency. The proposed hybrid converter includes two sub-converters sharing two power switches. One is a three-level PWM converter and the other is a LLC converter. The LLC converter and the three-level converter share the lagging-leg switches and extend the zero-voltage switching (ZVS) range of the lagging-leg switches from nearly zero to full load since the LLC converter can be operated at f_sw (switching frequency) $\approx$ f_r (series resonant frequency). A passive snubber is used on the secondary side of the three-level converter to decrease the circulating current on the primary side, especially at high input voltage and full load conditions. Thus, the conduction losses due to the circulating current are reduced. The output sides of the two converters are connected in series. Energy can be transferred from the input voltage to the output load within the whole switching period. Finally, the effectiveness of the proposed converter is verified by experiments with a 1.44kW prototype circuit.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.56 no.12
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• pp.2217-2220
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• 2007

In this paper, we propose a new wafer level package (WLP) for the RF MEMS applications. The Film Bulk Acoustic Resonator (FBAR) are fabricated and hermetically packaged in a new wafer level packaging process. With the use of Au-Sn eutectic bonding method, we bonded glass cap and FBAR device wafer which has groove-shaped via formed in the backside. The device wafer includes a electrical bonding pad and groove-shaped via for connecting to the external bonding pad on the device wafer backside and a peripheral pad placed around the perimeter of the device for bonding the glass wafer and device wafer. The glass cap prevents the device from being exposed and ensures excellent mechanical and environmental protection. The frequency characteristics show that the change of bandwidth and frequency shift before and after bonding is less than 0.5 MHz. Two packaged devices, Tx and Rx filters, are attached to a printed circuit board, wire bonded, and encapsulated in plastic to form the duplexer. We have designed and built a low-cost, high performance, duplexer based on the FBARs and presented the results of performance and reliability test.

• Journal of the Korean Society of Safety
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• v.33 no.1
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• pp.118-127
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• 2018

The study aims present data collection on the current state of safety and safety consciousness in universities' laboratories to verify the relation between investigation factors and further draw implications. The first finding is that laboratories with high risk level do not have better safety management performance than those with lower risk level. Secondly, labs that experienced accidents has a higher level of control than those without any. Regarding to the university's acceptance of safety requirements, the group with a high level of risk awareness or accidents were concerned that their universities did not provide sufficient support in safety management. It means that safety is low on the list of priorities in Universities' overall agenda and individual labs are responsible of their own safety. Most of the causes of accidents in the labs are man-made than physical errors. It requires that continuous safety educations and measures through safe research activities are means to eliminate and reduce the individual's safety frigidity. Through the survey, it is known that current education's system and contents are too generalized to reflect the characteristics of each laboratory. Thus, it is difficult to recognize various risk situations and to actually prevent safety accidents. Therefore, it is necessary to shift to customized curriculum and system for various major fields.

• ETRI Journal
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• v.40 no.5
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• pp.664-676
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• 2018

Given the rapidly increasing market penetration of photovoltaic (PV) systems in many fields, including construction and housing, the effective maintenance of PV systems through remote monitoring at the panel level has attracted attention to quickly detect faults that cause reductions in yearly PV energy production, and which can reduce the whole-life cost. A key point of PV monitoring at the panel level is cost-effectiveness, as the installation of the massive PV panels that comprise PV systems is showing rapid growth in the market. This paper proposes an implementation method that involves the use of a panel-level wireless PV monitoring module (WPMM), and which assesses the cost-effectiveness of this approach. To maximize the cost-effectiveness, the designed WPMM uses a voltage-divider scheme for voltage metering and a shunt-resistor scheme for current metering. In addition, the proposed method offsets the effect of element errors by extracting calibration parameters. Furthermore, a design method is presented for portable and user-friendly PV monitoring, and demonstration results using a commercial 30-kW PV system are described.

• The Transactions of the Korean Institute of Power Electronics
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• v.6 no.1
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• pp.64-73
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• 2001

This paper presents a Zero Voltage and Zero Current Switching (ZVZCS) 3-Level DC/DC converter. This converter overcomes the drawbacks presented by the conventional Zero Voltage Switching(ZVS) 3-Level converter, such as high circulating energy, severe parastic ringing on the rectifier diodes, and limited ZVS load range for the inner switches. The converter presented in this paper uses a phase shift control with a flying capacitor in the primary side to achieve ZVS for the outer switches. Additionally, the converter uses an energy recovery snubber to reset the primary current during the free-wheeling stage to achieve ZCS for the inner switches. The proposed converters are analyzed and verified on 6kW, 39kHz experimental prototype.

• Korean Journal of Occupational Health Nursing
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• v.20 no.3
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• pp.261-269
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• 2011

Purpose: The purpose of this study was to investigate occupational stress and fatigue level of neonatal nurses and to assess relationship between the two of them. Methods: Subjects were 109 neonatal nurses working at 2 university hospitals and 9 women's hospitals in D city, and the data were analyzed using descriptive statistics and binary logistic regression analysis by the SPSS/WIN 15.0. Results: The mean score of nurses' occupational stress level was 3.22, and the highest was 'night shift' among the 7 subcategories, and fatigue level was 62.0, and the highest was physical fatigue in configuration field. In logistic regression analyses, 'heavy workload' and 'inadequate physical environment' led to most occupational stress. Conclusion: In addition to significantly higher levels of occupational stress of neonatal nurses, the cumulative fatigue also resulted in decreased quality of nursing, job satisfaction and nursing productivity; therefore, appropriate number of nurses and improvement of work environment is necessary. Furthermore, to reduce the occupational stress and fatigue, we should try to develop adequate clinical guidelines and intervention strategies and apply them in neonatal care unit.

• Preventive Nutrition and Food Science
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• v.10 no.2
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• pp.161-166
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• 2005

We investigated the effect of pycnogenol (PYC) supplementation on retarding the immune dysfunction of CS7BL/6 mice after murine AIDS (MAIDS) development. Dysfunction of T and B cell mitogenesis from primary cultured splenocytes has been observed with retrovirus infection and PYC supplementation partially recovered the dysfunction of T and B cells. There was an abnormal shift of cytokine pattern with retrovirns infection, which was designated by the decreased secretion of Th1 cytokines and increased secretion of Th2 cytokines. PYC supplementation increased IL-2 and $IFN-\gamma$ secretion and decreased IL-4, IL-6, and $TNF-\alpha$ secretion, but it was not sufficient enough to maintain the normal level of these cytokines. Hepatic vitamin E level was significantly decreased by retrovirns infection, in accordance with increased hepatic lipid peroxidation level, whereas PYC supplementation normalized the hepatic level of vitamin E and lipid peroxidation. This study suggests that PYC supplementation may partially help retard the incidence of symptoms during MAIDS.

• Journal of the Korean Society of Systems Engineering
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• v.13 no.2
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• pp.57-64
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• 2017

A new paradigm based on distributed manufacturing services is emerging. This paradigm shift can be realized by smart functions and smart technologies such as Cyber Physical System (CPS), Artificial Intelligence (AI), and Cloud Computing. Most architectures define stack levels from Level 0 (equipment) to Level 4 (business area) and specify the services to be provided between them. Because of their a rough technical specification, there is a limitation on how to actually utilize a technology to actually implement a smart factory service with this architecture. In this paper, we propose a smart factory architecture that can be utilized directly from the perspective of a smart service system by making the use of System Engineering Process and System Modeling Language (SysML).