• Journal of the Korea Convergence Society
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• v.7 no.3
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• pp.149-157
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• 2016

For workers, industrial accidents exert a bad effect on the productivity, quality of life, and depress the morale. This study aimed to examine the overall influence on job performance of employees who returned to work after industrial accidents. This was a cross-sectional study using the data of 2013 and 2014 Panel Study of Worker's Compensation Insurance (PSWCI), and we performed logistic-regression analysis to analyze an affinity between general characteristics and job performance as independent variable and outcome variable, respectively. As a result, the major factor depressed the job performance were the 1 - 7 degree of disabilities and injuries with convalescence period for 6 to 9month or more than 12 months. In other words, this study shown that job performance was decreased as higher degree of disability and longer convalescence period. Job performance is the factor to identify indirectly worker's successful return to work, and it is important in follow-up of workers who returned to work after industrial accidents. Stable job performance of an industrial disaster victim is the key factor to maintain worker's comfortable and qualitative life as well as increase of productive capacity.

• Journal of the Korea Concrete Institute
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• v.19 no.4
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• pp.411-420
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• 2007

The applicability of headed bars in exterior beam-column joints under reversed cyclic loading was investigated. A total of ten pullout tests were first performed to examine pullout behavior of headed bars subjected to monotonic and cyclic loading with test variables such as connection type between head and bar stem (weld or no weld), loading methods (monotonic or cyclic loading), and head shape (small or large circular head and square head). Two full-scale beam-column joint tests were then performed to compare the structural behavior of exterior beam-column joints constructed using two different reinforcement details: i.e. $90^{\circ}$ standard hooks and headed bars. Both joints were designed following the recommendations of ACI-ASCE Committee 352 for Type 2 performance: i.e. the connection is required to dissipate energy through reversals of deformation into inelastic range. The pullout test results revealed that welded head to the stem did not necessarily result in increased pullout strength when compared to non-welded head. Relatively large circular head resulted in higher peak load than smaller circular and square head. Both beam-column joints with conventional $90^{\circ}$ hooks and headed bars behaved similarly in terms of crack development, hysteresis curves, and peak strengths. The joint using the headed bars showed better overall structural performance in terms of ductility, deformation capacity, and energy dissipation. These experimental results demonstrate that the headed bars using relatively small head can be properly designed far use in external beam-column joint.

• Journal of architectural history
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• v.20 no.3
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• pp.7-22
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• 2011

With the accumulations of outcomes from archaeological excavations of mountain fortress of three kingdoms period, there have been studies about time-periodic territory range of mountain fortress, difference in the way(method) of construction, defence system and so on from various points of view. This is an empirical study on the construction method of the valley part of stone fortress. First of all, it is required to secure large quantity of fresh water for those who lived at mountain fortress. Especially when builders of fortress construct a fortification at the valley part of stone fortress, in advance they must sufficiently consider several options including the establishment of sustainable water resources. First, when it comes to build a fortification on a ridge[or a slope] of a mountain, you have only to consider a vertical stress. However, when it comes to build a fortification at the valley part of a mountain, You must have more sufficient preparations for the constructing process. Because there are not only a vertical stress but also a horizontal pressure simultaneously. Second, a fortification of mountain fortress built by using unit building stone is a structure of masonry construction like brick construction, and the valley part of it is where the construction of the fortification begins. Third, when it comes to build a fortification at the valley part of a mountain, it seems that they use a temporary method such as coffer dam in oder to prevent the collapse of the fortification due to heavy rain. Furthermore, in response to a horizontal pressure a fortification is built by the way of its plane make an arch, or by piling up the soil with the plate method(類似版築) and earthen wall harder method(敷葉) they increase cross-sectional area of the fortification and its cutoff capacity. In front direction they put the reservoir facility for the fear that the hydraulic pressure and earth pressure are directly transmitted to the fortification. The process of constructing the fortification at the valley part of a mountain is done in the same oder as follows; leveling of ground(整地) ${\Rightarrow}$ construction of coffer dam ${\Rightarrow}$ construction of the fortification between the both banks of the valley ${\Rightarrow}$ construction of the fortification at bottom part of spill way(餘水路) between the both banks of the valley ${\Rightarrow}$ construction of spill way(餘水路) & reservoir facility ${\Rightarrow}$ construction of the fortification at upper part of spill way between the both banks of the valley. Coffer dam facility seems to be not only the protection device on occasion of flood but also an important criterion to measure the proper height of spill way or tailrace(放水路). This study has a meaningful significance in that it empirically examines the method of reduction of the horizontal pressure which the fortification at the valley part of a mountain takes, the date the construction was done, and wether the changes in climate such as heavy rainfall influence the process of construction.

• Journal of Korean Society of Steel Construction
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• v.27 no.2
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• pp.195-205
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• 2015

The rahmen bridge is well known common type of bridge in which all members are connected rigidly. The rahmen bridge is built for several situations because it has many advantages such as no need of bridge bearing system, easy of maintenance, reduction of the cross-sectional area of superstructure, and relatively low construction cost compared with other bridge types. Recently, to lengthen the span of rahmen bridge system, steel-concrete composite beam is used for superstructure of rahmen bridge instead of normal concrete girder with slab. However, member forces are increased because of extension of span length of superstructure and substructure is designed and constructed inefficiently when steel-concrete composite rahmen bridge is designed. In this study, new-type steel-concrete composite bridge is suggested. New-type steel-concrete composite rahmen bridge is adopted hinge connection between abutment and foundation for the reduction of the bending momemt at the foundation. In this study, we present the results of experiment conducted to estimate the load carrying capacity of new-type steel-concrete composite rahmen bridge and the structural characteristics of hinge connection.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.6
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• pp.126-136
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• 2018

A steel-plate concrete composite beam is composed of a steel plate, concrete and shear connector to combine inhomogeneous two materials. The steel plate is assembled by welding an existing composite beam. In this study, new steel-plate concrete composite beam, called a SPC Beam, was developed to reduce the shear connector and improve the workability. The SPC Beam was composed of folding steel plates and concrete, without a shear connector. The folding steel plate was assembled using high strength bolt instead of welding. To improve the workability in field construction, a hat-shaped Cap was attached to the junction with a slab. Monotonic load testing under two points was conducted under displacement control mode. The flexural strength of the specimen for positive moment and negative moment was calculated using the plastic stress distribution method. The test results showed that the flexural strength of the new SPC Beam had 80% of the strength of a complete composite beam. In addition, increasing the composite ratio was possible through clearance controls of the cap. In this study, the performance of the SPC Beam was verified through additional experiments and analyses with the cross-sectional shape and cap as variables, because the representative shape in the positive negative moment region is targeted.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.9
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• pp.435-445
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• 2018

This study analyzed factors that should be considered in the process of export diversification strategy formulation and priorities of strategies. We reviewed the extant literature and interviewed six experts. Cross-sectional analysis of a literature review and interview results were used to determine the influencing factors of export. The data for this study were collected from a survey of 68 export experts in Automotive Parts enterprises. Data were analyzed using AHP. As a result of the analysis, the order of importance appeared in the order of internal capacity, correlation buyer effect, entry barriers, technology response, and competition environment. The regions with a high overseas level were product differentiation, centralization, and low cost, whereas those with a low level were in the order of low cost, product differentiation, and concentration. It is meaningful to review the alternatives for adoption of the export diversification strategy and establish a strategy appropriate to the situation. It is necessary to establish a customized strategy considering the characteristics of the global region, and not only internal competence but also mutual relationship with local buyers are important.

• Journal of the Korean Electrochemical Society
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• v.4 no.3
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• pp.104-108
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• 2001

Naphthalene derived mesophase pitch WP) was spun into short fibers by using melt-blown technology. The pitch fibers oxidative stabilization were carried out heating rates of $2^{\circ}C/min,\;5^{\circ}C/min\;and\; 10^{\circ}/min$. The heating rate was a key factor to maximate the capacity of the Li-ion secondary battery through controlling the morphology of the graphitized fiber. The diameters of the melt-blown fibers prepared were in the range of $4{\mu}m\~16{\mu}m$ with functions of air jet speed, air temperature and the temperature of the nozzle. The graphitized fibers of $10{\mu}m$ diameters showed various morphological structure with heating rate of the stabilization. Radial, radial-random and skin-core cross-sectional structure of the fibers were observed at the respective heating rate of $2^{\circ}C/min\;5^{\circ}C/min\;and\;10^{\circ}C/min$. Most crystalline structure of graphite was obtained from the fiber stabilized at heating rate of $10^{\circ}C/min$ exhibiting the best anode performance with 400 mAh/g of capacitance and $96.8\%$ of charge/discharge efficiency.

• Journal of the Korea Concrete Institute
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• v.23 no.3
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• pp.321-330
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• 2011

Recently, the effects of high temperature and fiber content on the residual mechnical properties of high-strength concrete were experimentally investigated. In this paper, residual mechanical properties of concrete with water to cement (w/c) ratios of 0.55, 0.42 and 0.35 exposed to high temperature are compared with those obtained in fiber reinforced concrete with similar characteristics ranging from 0.05% to 0.20% polypropylene (PP) fiber volume percentage. Also, factors including pre-load levels of 20% and 40% of the maximum load at room temperature are considered. Outbreak time, thermal strain, length change, and mass loss were tested to determine compressive strength, modulus of elasticity, and energy absorption capacity. From the results, in order to prevent the explosive spalling of 50 MPa grade concretes exposed to high temperature, more than 0.05 vol. % of PP fibers is needed. Also, the cross-sectional area of PP fiber can influence the residual mechanical properties and spalling tendency of fiber reinforced concrete exposed to high temperature. Especially, the external loading increases not only the residual mechanical properties of concrete but also the risk of spalling and brittle failure tendency.

• Korea journal of population studies
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• v.20 no.2
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• pp.135-159
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• 1997

Education effect on women's participation in the labor market has been known to be small in Korea. Then, the meaning of women's education as human capital needs to be questioned. Both the increasing desire for working among women and the criticism to under-utilization of women's education in the labor market reflect that women's education is surely perceived as human capital. However, women's education dose not seem to function well as human capital in the labor market. According to previous studies, it is pointed out that educational effect on women's participation in the labor market is weak but the effect on earnings is evident. There were few attempts to evaluate economic returns to women's education over the life-cycle analyzing both working and non-working women. Considering that the economic behaviors of women in nonagricultural sector have changed little until the mid-1980s, I tried to examine the meaning of education as human capital over the women's life cycle using cross - sectional data. This study shows that the educational effect on women's participation in the labor market does not exist and the working period is very short. Although the educational effect on earnings among working women is clearly shown, it tends to limited to younger women. Despite the educational effect on earnings among younger women, the meaning of education as human capital among Korean women does not hold well due to short working period and the low participation of the educated in the labor market.

• Journal of Nutrition and Health
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• v.32 no.8
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• pp.887-896
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• 1999

The purpose of this research is to assess hematological and biochemical status and the prevalence of iron deficiency of pregnant women by gestational age to provide the primary data about iron nutritional status of pregnant women. Pregnant women visiting public health centers in Ulsan participated in study and were divided into 3 trimester by last menstrual period(LMP). Hemoglobin (Hgb), hematocrit(Hct)and mean corpuscular volume(MCV) among iron status indices were not statistically different from normal distribution, however total iron binding capacity(TIBC) and serum ferritin were skewed to left and serum iron and transferrin saturation(TS) were skewed to right. Hgb was positively correlated with Hct(r=0.93, p<0.001) but TIBC was negatively correlated with all indices. Serum ferritin was also correlated with all indices, especially in 3rd trimester but not reached to 1st trimester level. Mean corpuscular hemoglobin(MCH), mean corpuscular hemoglobin concentration(MCHC), Red cell distribution width(RDW), serum iron and TS were not significantly different by trimester, however when serum serum iron was adjusted with hematocrit to correct the hemodilution, it significantly decreased in 2nd trimester. MCV increased in 2nd trimester and was maintained until late pregnancy, TIBC continued to increase throughout the trimester. The prevalence of anemic by CDC(Centers for Disease Control) Hgb criteria(Hgb <11.0g/dl in 1st and 3nd trimester, Hgb<10.5g/dl in 2nd trimester) was 2.8% in 1st trimester, 22.5% in 2nd trimester, 27.1% in 3rd trimester and was similar with prevalence by CDC Hct criteria(Hct < 33% in 1st and 3rd, Hct < 32% in 2nd). The prevalence of anemic of total subjects was 32.7% by WHO criteria(Hgb < 11.0g/dl). Although almost iron status indices increased in 3rd trimester, the prevalence of anemia by different criteria of all indices increased throughout the trimester, so iron nutritional status was considered as serious during late pregnancy. However, since factors other than iron deficiency, such as infection, infection, inflammation, other nutrient deficiency may also play a significant role, to differentiate the anemia due to mainly iron deficiency from the anemia due to other factors, serum ferritin is among the more useful indices in distinguishing the two conditions because it is depressed only in iron deficiency. Hgb<11.0g/dl and serum ferritin<12.0ug/L as the criteria of iron deficiency was suggested by CDC. 17.8% of all subjects were classified as iron deficient anemia, 14.9% as anemic from other reasons, 21.2% as iron deficiency any only 46.2% were in normal iron status.