• Journal of Labour Economics
• /
• v.39 no.3
• /
• pp.99-124
• /
• 2016

This study analyzed the effects of labor unions on the wages of Korean female workers using 'Korean Labor and Income Panel Study.' In the estimation we considered the self-selection bias due to the women's labor force participation decision and a plausible non-response bias from not answering the question about the company size in terms of number of employees. By fixed effect estimation we found that labor unions in Korea do not increase the wages of both the female union workers and non-union workers who work at a company in which a union is organized comparing to female workers who work at company without a union. This results indicates that female workers who work in the company with labor union tend to have unobserved characteristics that are positively correlated with both wages and the probability to enter the company with labor union. We also came to the conclusion that there is no free-rider effects of non-union workers.

• Architectural research
• /
• v.15 no.3
• /
• pp.151-158
• /
• 2013

Offshore oil and gas process plants are exposed to hazardous accidents such as explosion and fire, so that the structural components should resist such accidental loads. Given the possibilities of thousands of different scenarios for the occurrence of an accidental hazard, the best way to predict a reasonable size of a specific accidental load would be the employment of a probabilistic approach. Having the fact that a specific procedure for probabilistic accidental hazard analysis has not yet been established especially for explosion and fire hazards, it is widely accepted that engineers usually take simple and conservative figures in assuming uncertainties inherent in the procedure, resulting either in underestimation or more likely in overestimation in the topside structural design for offshore plants. The variation in the results of a probabilistic approach is determined by the assumptions accepted in the procedures of explosion probability computation, explosion analysis, and structural analysis. A design overpressure load for a sample offshore plant is determined according to the proposed probabilistic approach in this study. CFD analysis results using a Flame Acceleration Simulator, FLACS_v9.1, are utilized to create an overpressure hazard curve. Moreover, the negative impulse and frequency contents of a blast wave are considerably influencing structural responses, but those are completely ignored in a widely used triangular form of blast wave. An idealistic blast wave profile deploying both negative and positive pulses is proposed in this study. A topside process module and piperack with blast wall are 3D FE modeled for structural analysis using LS-DYNA. Three different types of blast wave profiles are applied, two of typical triangular forms having different impulse and the proposed load profile. In conclusion, it is found that a typical triangular blast load leads to overestimation in structural design.

• Journal of Korea Water Resources Association
• /
• v.49 no.1
• /
• pp.41-49
• /
• 2016

This study proposed a new drought index considering the accumulative pattern of daily rainfall, i.e., Rainfall Accumulation Drought Index (RADI). The RADI can be easily calculated at daily scale by comparing the long-term averaged cumulative rainfall to the observed cumulative rainfall for a specific duration. This study evaluated the availability of the RADI in the field of monitoring short-term and long-term droughts by investigating the spatial and temporal variability and the recurrence cycle of drought in South Korea. To present the short-term and long-term droughts, the various SPIs with different durations should be used in practice. However, the RADI can present and monitor both short-term and long-term droughts as a single index. By investigating the national average of the RADI, specific drought patterns of 20-year cycle were identified in this study. This study also proposed a five-level drought classification considering occurrence probability that would be a suitable alternative as a drought criterion for drought forecast/response.

• Development and Reproduction
• /
• v.18 no.1
• /
• pp.1-11
• /
• 2014

Early growth response 1 (Egr1) is a zinc-finger transcription factor to direct second-wave gene expression leading to cell growth, differentiation and/or apoptosis. While it is well-known that Egr1 controls transcription of an array of targets in various cell types, downstream target gene(s) whose transcription is regulated by Egr1 in the uterus has not been identified yet. Thus, we have tried to identify a list of potential target genes of Egr1 in the uterus by performing multi-step in silico promoter analyses. Analyses of mRNA microarray data provided a cohort of genes (102 genes) which were differentially expressed (DEGs) in the uterus between Egr1(+/+) and Egr1(-/-) mice. In mice, the frequency of putative EGR1 binding sites (EBS) in the promoter of DEGs is significantly higher than that of randomly selected non-DEGs, although it is not correlated with expression levels of DEGs. Furthermore, EBS are considerably enriched within -500 bp of DEG's promoters. Comparative analyses for EBS of DEGs with the promoters of other species provided power to distinguish DEGs with higher probability as EGR1 direct target genes. Eleven EBS in the promoters of 9 genes among analyzed DEGs are conserved between various species including human. In conclusion, this study provides evidence that analyses of mRNA expression profiles followed by two-step in silico analyses could provide a list of putative Egr1 direct target genes in the uterus where any known direct target genes are yet reported for further functional studies.

• The Korean Journal of Physiology and Pharmacology
• /
• v.5 no.5
• /
• pp.413-421
• /
• 2001

An impaired smooth muscle cell (SMC) relaxation of coronary artery by alteration of $K^+$ channels would be the most potential explanation for reduced coronary reserve in left ventricular hypertrophy (LVH), however, this possibility has not been investigated. We performed morphometrical analysis of the coronary artery under electron microscopy and measured $Ca^{2+}-activated\;K\;(K_{Ca})$ currents and delayed rectifier K $(K_{dr})$ currents by whole-cell and inside-out patch-clamp technique in single coronary arterial SMCs from rabbits subjected to isoprenaline-induced cardiac hypertrophy. Coronary arterial SMCs underwent significant changes in ultrastructure. The unitary current amplitude and the open-state probability of $K_{Ca}$ channel were significantly reduced in hypertrophy without open-time and closed-time kinetic. The concentration-response curve of $K_{Ca}$ channel to $Ca^{2+}$ is shifted to the right in hypertrophy. The reduction in the mean single channel current and increase in the open channel noise of $K_{Ca}$ channel by TEA were more sensitive in hypertrophy. $K_{dr}$ current density is significantly reduced in hypertrophy without activation and inactivation kinetics. The sensitivity of $K_{dr}$ current on 4-AP is significantly increased in hypertrophy. This is the first study to report evidence for alterations of $K_{Ca}$ channels and $K_{dr}$ channels in coronary SMCs with LVH. The findings may provide some insight into mechanism of the reduced coronary reserve in LVH.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
• /
• v.10 no.2
• /
• pp.87-96
• /
• 2012

With a view to determine a safe speed the limit of a manipulator arm, several experiments was performed with a multi-jointed manipulator in maintenance and decommissioning tasks of nuclear facilities. Under the simulated emergency conditions, which were generated with random combinations of manipulator arm speed, failure probability and failure type, response characteristics of human operators to various malfunctions of a manipulator arm were measured in terms of reaction time, number of false alarm, and number of misses. This paper demonstrated that failure type, manipulator axes and manipulator arm speed has significant effects on human reaction time. As a whole the reaction time was slightly increased with manipulator arm speed, which is showed somewhat different pattern due to failure type. The reaction time to an axis acting on a workpiece directly, which could flex and extend, was fastest and much more its standard deviation was small. Various factors which may affect safe speed were also described.

• International Journal of Highway Engineering
• /
• v.15 no.4
• /
• pp.127-133
• /
• 2013

PURPOSES : The impact performance of flexible barrier system such as structural response, vehicular motion and occupant safety vary depending on the impact point. Thus, to properly evaluate the performance of a flexible barrier system, impact should be made to a point which will lead to the worst possible results. This point is called the Critical Impact Point (CIP). This paper presents the way to determine the CIP for a SB2 class flexible barrier system which is consisted of Thrie-Beam rail and circular hollow tube post of 2m span. METHODS: Barrier VII simulations were made for impact points; Case 1 at a post, Case 2 at 1/3 span downstream from a post, Case 3 at middle of the span, Case 4 at 2/3 span downstream from a post. For the structural performance (deflections), impact simulation of 8000kg-65km/h-15degree was used, and for vehicle motion and occupant safety, simulation of 1300kg-80km/h-20degree impact was made and analysed. RESULTS: Case 1 gave the largest dynamic deflection of 75.72cm and also gave the largest snag value of 44.3cm. Occupant safety and exit angle of the vehicle after the impact were not sensitive to the impact point and were all below the allowable limit. CONCLUSIONS : For the SB2 class flexible barrier system's CIP can be regarded as a post which is sufficiently away from the end of Length of Need in order to avoid the end-effect of the barrier system. It can be more economic in the long run because the normal concrete pavement material is likely to cost more due to higher probability of maintenance and repair and higher social cost due to traffic accident, etc.

• Radiation Oncology Journal
• /
• v.30 no.1
• /
• pp.43-48
• /
• 2012

Purpose: To develop the dose volume histogram (DVH) management software which guides the evaluation of radiotherapy (RT) plan of a new case according to the biological consequences of the DVHs from the previously treated patients. Materials and Methods: We determined the radiation pneumonitis (RP) as an biological response parameter in order to develop DVH management software. We retrospectively reviewed the medical records of lung cancer patients treated with curative 3-dimensional conformal radiation therapy (3D-CRT). The biological event was defined as RP of the Radiation Therapy Oncology Group (RTOG) grade III or more. Results: The DVH management software consisted of three parts (pre-existing DVH database, graphical tool, and $Pinnacle^3$ script). The pre-existing DVH data were retrieved from 128 patients. RP events were tagged to the specific DVH data through retrospective review of patients' medical records. The graphical tool was developed to present the complication histogram derived from the preexisting database (DVH and RP) and was implemented into the radiation treatment planning (RTP) system, $Pinnacle^3$ v8.0 (Phillips Healthcare). The software was designed for the pre-existing database to be updated easily by tagging the specific DVH data with the new incidence of RP events at the time of patients' follow-up. Conclusion: We developed the DVH management software as an effective tool to incorporate the phenomenological consequences derived from the pre-existing database in the evaluation of a new RT plan. It can be used not only for lung cancer patients but also for the other disease site with different toxicity parameters.

• Earthquakes and Structures
• /
• v.18 no.2
• /
• pp.147-162
• /
• 2020

This paper presents a novel precast energy dissipation shear wall (PEDSW) structure system that using mild steel dampers as dry connectors at the vertical joints to connect adjacent wall panels. Analytical studies are systematically conducted to investigate the seismic performance of the proposed PEDSW under sequence-type ground motions. During earthquake events, earthquake sequences have the potential to cause severe damage to structures and threaten life safety. To date, the damage probability of engineering structures under earthquake sequence has not been included in structural design codes. In this study, numerical simulations on single-story PEDSW are carried out to validate the feasibility and reliability of using mild steel dampers to connect the precast shear walls. The seismic responses of the PEDSW and cast-in-place shear wall (CIPSW) are comparatively studied based on nonlinear time-history analyses, and the effectiveness of the proposed high-rise PEDSW is demonstrated. Next, the foreshock-mainshock-aftershock type earthquake sequences are constructed, and the seismic response and fragility curves of the PEDSW under single mainshock and earthquake sequences are analyzed and compared. Finally, the fragility analysis of PEDSW structure under earthquake sequences is performed. The influences of scaling factor of the aftershocks (foreshocks) to the mainshocks on the fragility of the PEDSW structure under different damage states are investigated. The numerical results reveal that neglecting the effect of earthquake sequence can lead to underestimated seismic responses and fragilities, which may result in unsafe design schemes of PEDSW structures.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.11 no.5
• /
• pp.1805-1813
• /
• 2010

This paper presented regarding an parametric study to investigate seismic capacity evaluation of semi-rigid steel frame infilled with composit panel. In order to propose the optimum retrofit of the steel frame, we analysed the various pattern of retrofitted steel frame subjected to weak/medium earthquake. Steel frame with composit panel was analysed by Time history analyses analysis. The model were analysed using the suites of ground motion developed by NEHRP project on steel moment resisting frame. These earthquakes consist of 20 horizontal ground acceleration record each, i.e., a 10%, 50% probability of accidence in a 50 year period. We considered the semi-rigid connection which are commonly used in field, and modeled the nonlinear connection element (GAP) between panel and frame. It was shown that how is the steel frame with composit panel effected. We also examined the response of retrofitted frame.