• Journal of Labour Economics
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• v.40 no.4
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• pp.115-158
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• 2017

This paper explores the relationship between working hours and the residual gender wage gap in Korea. Because the labor practice of working long hours in Korea favors men, who tend to spend little time on domestic labor, long working hours can influence the residual gender wage gap by discriminating against women. We analyze this discrimination empirically, and find the following results. First, the returns from working long hours are not high in most occupations in Korea. Second, working hours have a positive effect on the residual gender wage gap in male-dominated occupations, but not in female-dominated ones.

• Journal of the Korean Vacuum Society
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• v.10 no.2
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• pp.194-200
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• 2001

In this study, the optical properties of diamond-like carbon(DLC) films, which was synthesized by 13.56 MHz rf plasma enhanced chemical vapor deposition system(PECVD), were investigated. We observed the variation of the transmittance and optical band gap with respect to deposition condition. The change of the transmittance and optical band gap of the DLC films were investigated as a function of RF power, working pressure, and additional gas. The optical band gap decreased with the increase of RF power and working pressure. We could verify the bond structures change of DLC films by observing the content of hydrogen using FT-IR spectroscopy. And the addition of hydrogen and nitrogen decreased the optical band gap by the breakage of C-H bond of DLC films during the deposition.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.21 no.1
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• pp.53-61
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• 1997

The performance characteristics of magnetic fluid seals are studied numerically as a function of working gap, pole width, angle of pole sharpening, and shaft speed. The temperature distribution of a magnetic fluid seal with multiple tooth is investigated as a function of the contact fraction of magnetic fluids at the periphery of pole tooth using a finite element method. The most significant design parameter of a magnetic fluid seal is the working gap between the pole pieces and the rotating shaft. The result shows that with increasing the working gap, the friction torque decreases radically. The practical working gap for the pole pieces with triangular tooth zone profile is 0.2-0.4mm. The FEM results indicate that the optimal filling of a magnetic fluid between the pole pieces and the shaft is very important due to the accumulations of nonuniform friction heating within the pole pieces, which may interfere the magnetic circuit flow.

• The Journal of Advanced Prosthodontics
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• v.9 no.6
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• pp.463-469
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• 2017

PURPOSE. To evaluate the fit of a three-unit metal framework of fixed dental prostheses made by subtractive and additive manufacturing. MATERIALS AND METHODS. One master model of metal was fabricated. Twenty silicone impressions were made on the master die, working die of 10 poured with Type 4 stone, and working die of 10 made of scannable stone. Ten three-unit wax frameworks were fabricated by wax-up from Type IV working die. Stereolithography files of 10 three-unit frameworks were obtained using a model scanner and three-dimensional design software on a scannable working die. The three-unit wax framework was fabricated using subtractive manufacturing (SM) by applying the prepared stereolithography file, and the resin framework was fabricated by additive manufacturing (AM); both used metal alloy castings for metal frameworks. Marginal and internal gap were measured using silicone replica technique and digital microscope. Measurement data were analyzed by Kruskal-Wallis H test and Mann-Whitney U-test (${\alpha}=.05$). RESULTS. The lowest and highest gaps between premolar and molar margins were in the SM group and the AM group, respectively. There was a statistically significant difference in the marginal gap among the 3 groups (P<.001). In the marginal area where pontic was present, the largest gap was $149.39{\pm}42.30{\mu}m$ in the AM group, and the lowest gap was $24.40{\pm}11.92{\mu}m$ in the SM group. CONCLUSION. Three-unit metal frameworks made by subtractive manufacturing are clinically applicable. However, additive manufacturing requires more research to be applied clinically.

• 한국전산유체공학회:학술대회논문집
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• 2009.04a
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• pp.347-354
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• 2009

Plate Heat Exchnager(PHE) has recently become widely adopted for cogeneration systems owing to its small installation space and high thermal efficiency. The gap between plates can be changed depending on its assemble type, i.e. gasket or blazing. The gap is known to affect thermal efficiency and working pressure drop in PHE with complicated geometrical features. Numerical simulation techniques have been developed to deal with PHE with complex configuration of chevron plates. The present study is aiming at identifying the gap effect on pressure drop and thermal efficiency of the PHE. The numerical simulation results show that the gap has relatively large effects on working pressure drop than thermal efficiency in performance of PHE.

• Journal of Welding and Joining
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• v.14 no.4
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• pp.79-88
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• 1996

For improvement in productivity and weld quality, weld seam tracking and welding parameter control are very essential in the welding of a structure which can not be cxactly fit-up due to mismatch, discontinous gap, deflection, etc.. In this study, an automatic weld seam tracking system is developed for I-butt joint structure, and the system consists of XYZ working table, vision sensor and user interface program. In the developed vision sensor system, an image projection algorithm for weld-line detection and an adaptive current control algorithm for gap variation were implemented. The user interface program developed in this study by basing on the objct oriented concept could provide very convenient way to utilize the tracking system with the pull-down menu driven structure. The developed system showed a good seam tracking and weld quality control capability corresponding to deflected weld lines and gap variations.

• 연구논문집
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• s.33
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• pp.53-65
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• 2003

Electrostatic micro-motors can be divided into three classes: (i) salient type side drive motor, (ii) radial gap type wobble motor, (iii) axial gap type wobble motor. The working mechanism, torque evaluation, fabrication, and operational characteristics of each micro motors are compared. It is proved that axial gap type wobble motor has the bigger generating torque than that of the other type. The gear ratio of wobble motors increases the driving torque at the cost of a decreasing angular speed and decreases the friction because of the rolling motion instead of sliding at the bearing. Techniques for characterizing micro-motors performance are presented.

• The Journal of Advanced Prosthodontics
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• v.6 no.1
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• pp.22-29
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• 2014

PURPOSE. This study aimed to investigate the potential clinical application of digitized silicone rubber impressions by comparing the accuracy of zirconia 3-unit fixed partial dentures (FPDs) fabricated from 2 types of data (working model and impression) obtained from a laser scanner. MATERIALS AND METHODS. Ten working models and impressions were prepared with epoxy resin and vinyl polysiloxane, respectively. Based on the data obtained from the laser scanner (D-700; 3Shape A/S, Copenhagen, Denmark), a total of 20 zirconia frameworks were prepared using a dental CAD/CAM system (DentalDesigner; 3shape A/S, Copenhagen, Denmark / Ener-mill, Dentaim, Seoul, Korea). The silicone replicas were sectioned into four pieces to evaluate the framework fit. The replicas were imaged using a digital microscope, and the fit of the reference points (P1, P2, P3, P4, P5, P6, and P7) were measured using the program in the device. Measured discrepancies were divided into 5 categories of gaps (MG, CG, AWG, AOTG, OG). Data were analyzed with Student's t-test ($\alpha$=0.05), repeated measures ANOVA and two-way ANOVA (${\alpha}=0.05$). RESULTS. The mean gap of the zirconia framework prepared from the working models presented a narrower discrepancy than the frameworks fabricated from the impression bodies. The mean of the total gap in premolars (P=.003) and molars (P=.002) exhibited a statistical difference between two groups. CONCLUSION. The mean gap dimensions of each category showed statistically significant difference. Nonetheless, the digitized impression bodies obtained with a laser scanner were applicable to clinical settings, considering the clinically acceptable marginal fit ($120{\mu}m$).

• Health Policy and Management
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• v.10 no.1
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• pp.95-110
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• 2000

The purpose of this study is to evaluate work values of hospital employees. Their work values was compared with that of other corporate's employees or among that of specialties in hospital. It was surveyed to 893 persons; 164 in hospital and 709 in others. The work values of hospital employees are similar to that of other corporate's employees. But they have first priority to working environment, and emphasize monetary incentive much more than hierarchical development. There are some gap in work value between age groups in hospital, different from other corporate. That means hospital manager need to development the more developed work value in hospital. The work values are different in monetary incentive, hierarchical development, safety, working environment, creativity among specialties in hospital. The more special employees emphasize much more to monetary incentive, hierarchical development, working environment and the less special employees have priority to safety work value. Specially, because the hospital managers want to have safety than creativity, it must to make some changing program of work value for advance of future hospital.

• KDI Journal of Economic Policy
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• v.43 no.2
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• pp.53-79
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• 2021

The recession caused by the COVID-19 crisis has features that could disproportionately harm female employment. Risk of infection and social distancing measures may have disrupted jobs in face-to-face industries, which have traditionally hired more women than men. School closures and a consequent increase in childcare and homeschooling demands may have discouraged labor market participation by working mothers. Using the Economically Active Population Survey, I examine how female employment was affected by each factor. I find that the gender gap in the Employment to Non-participation (E to N) transition rates is twice as large as the gap in the Employment to Unemployment (E to U) transition rates. Women's overrepresentation in the face-to-face industries accounts for most of the gap in the E to U transition but only a third of the gap in the E to N transition. The rise in non-participation is especially pronounced among married women aged 39-44, the group most likely to have elementary-school-age children.