• Journal of the Korea Institute of Building Construction
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• v.20 no.2
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• pp.163-169
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• 2020

Construction is a typical labor-dependent industry. However, problems related to wage payment, which directly affects the livelihood of workers, have caused other problems in maintaining skilled workers, such as increasing the turnover rate of skilled workers, resulting in a shortage of skilled workers. Against this backdrop, this study was conducted to develop measures to improve the conventional wage payment systems in order to prevent skilled workers from leaving their jobs and to maintain them as workers. It is necessary to make the registration of non-registered small-sized construction companies in Korea mandatory, and to introduce means by which construction companies that hire workers through non-registered agents can be penalized. In addition, the project bank account (PBA) system used in the domestic banking sector can be benchmarked in operating payment systems, an approach that is expected to effectively prevent delayed wage payments in the construction industry.

• Journal of Microbiology and Biotechnology
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• v.26 no.12
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• pp.2087-2097
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• 2016

Most cold-adapted enzymes possess higher $K_m$ and $k_{cat}$ values than those of their mesophilic counterparts to maximize the reaction rate. This characteristic is often ascribed to a high structural flexibility and improved dynamics in the active site. However, this may be less convincing to cold-adapted metabolic enzymes, which work at substrate concentrations near $K_m$. In this respect, cold adaptation of a shikimate kinase (SK) in the shikimate pathway from psychrophilic Colwellia psychrerythraea (CpSK) was characterized by comparing it with a mesophilic Escherichia coli homolog (EcSK). The optimum temperatures for CpSK and EcSK activity were approximately $30^{\circ}C$ and $40^{\circ}C$, respectively. The melting points were $33^{\circ}C$ and $45^{\circ}C$ for CpSK and EcSK, respectively. The ${\Delta}G_{H_2O}$ (denaturation in the absence of denaturing agent) values were 3.94 and 5.74 kcal/mol for CpSK and EcSK, respectively. These results indicated that CpSK was a cold-adapted enzyme. However, contrary to typical kinetic data, CpSK had a lower $K_m$ for its substrate shikimate than most mesophilic SKs, and the $k_{cat}$ was not increased. This observation suggested that CpSK may have evolved to exhibit increased substrate affinity at low intracellular concentrations of shikimate in the cold environment. Sequence analysis and homology modeling also showed that some important salt bridges were lost in CpSK, and higher Arg residues around critical Arg 140 seemed to increase flexibility for catalysis. Taken together, these data demonstrate that CpSK exhibits characteristics of cold adaptation with unusual kinetic parameters, which may provide important insights into the cold adaptation of metabolic enzymes.

• The Korean Journal of Physiology and Pharmacology
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• v.18 no.2
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• pp.129-134
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• 2014

It has been suggested that transition metal ions such as iron can produce an oxidative injuries to nigrostriatal dopaminergic neurons, like Parkinson's disease (PD) and subsequent compensative increase of tetrahydrobiopterin ($BH_4$) during the disease progression induces the aggravation of dopaminergic neurodegeneration in striatum. It had been established that the direct administration of $BH_4$ into neuron would induce the neuronal toxicity in vitro. To elucidate a role of $BH_4$ in pathogenesis in the PD in vivo, we assessed the changes of dopamine (DA) and $BH_4$ at striatum in unilateral intranigral iron infused PD rat model. The ipsistriatal DA and $BH_4$ levels were significantly increased at 0.5 to 1 d and were continually depleting during 2 to 7 d after intranigral iron infusion. The turnover rate of $BH_4$ was higher than that of DA in early phase. However, the expression level of GTP-cyclohydrolase I mRNA in striatum was steadily increased after iron administration. These results suggest that the accumulation of intranigral iron leads to generation of oxidative stress which damage to dopaminergic neurons and causes increased release of $BH_4$ in the dopaminergic neuron. The degenerating dopaminergic neurons decrease the synthesis and release of both $BH_4$ and DA in vivo that are relevance to the progression of PD. Based on these data, we propose that the increase of $BH_4$ can deteriorate the disease progression in early phase of PD, and the inhibition of $BH_4$ increase could be a strategy for PD treatment.

• Journal of Korean Society on Water Environment
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• v.25 no.6
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• pp.821-831
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• 2009

The study was aimed to assess the expected impact of climate change on the water cycle and soil losses in Daecheong Reservoir watershed, Korea using the Soil and Water Assessment Tool (SWAT) that was validated for the watershed in a previous study. Future climate data including precipitation, temperature and humidity generated by introducing a regional climate model (Mesoscale Model Version 5, MM5) to dynamically downscale global circulation model (European Centre Hamburg Model Version 4, ECHAM4) were used to simulate the hydrological responses and soil erosion processes in the future 100 years (2001~2100) under the Special Report on Emissions Scenario (SRES) A1B. The results indicated that the climate change may increase in the amount of surface runoff and thereby sediment load to the reservoir. Spatially, the impact was relatively more significant in the subbasin Bocheongcheon because of its lower occupation rate of forest land compared to other subbasins. Seasonally, the increase of surface runoff and soil losses was more significant during late summer and fall season when both flood control and turbidity flow control are necessary for the reservoir and downstream. The occurrence of extreme turbidity flow events during these period is more vulnerable to reservoir operation because the suspended solids that remained water column can be resuspended by vertical mixing during winter turnover period. The study results provide useful information for the development of adaptive management strategy for the reservoir to cope with the expected impact of future climate change.

• Journal of radiological science and technology
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• v.20 no.1
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• pp.77-84
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• 1997

Job satisfaction is very important for adequate manpower management in the medical field. To study job satisfaction among the radiologic technologists, 344 cases were reviewed in five university hospitals and one general hospital. Self-administered questionnaire was used to study their socioeconomic characteristics, working conditions, job satisfaction, and the factors affecting there Job satisfaction. The results were as follows : 1. There was statistically significant difference in job satisfaction according to the their department of employment, position, and hospital characteristics. 2. The group that was satisfied with their salary had a higher job satisfaction score, whereas others who were not satisfied ranked lower. 3. The positive answering group on the ability and job recognition ranked higher score on the job satisfaction than the negative answering group. 4. The group that was in good relationship with their superiors and co-workers scored higher on job satisfaction From the above results, the job satisfaction was high for the group with positive thinking and reply, but the intentin to change their job was low. Considering the fact that these results represent only 6 hospitals from limited arease, therefore, necessary to include more medical facilities nationwide, especially small-medium sized clinics or hospitals where the difficulty with high turnover rate of employment is expected, to study further various factors involving job satisfaction in the future.

• Health Policy and Management
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• v.12 no.4
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• pp.1-17
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• 2002

This study was attempted to identify the liquidity trends and determinants of private hospitals in Korea different. Data used in this study were collected from 98 hospitals with complete general data of present conditions as well as financial statements(balance sheets, income statements). They were chosen from hospitals that passed the standardization audit undertaken by the Korean Hospital Association from 1996 to 2000 for the purpose of accrediting training hospitals. The dependent variables in this study were used current ration and quick ratio as a proxy indicator for liquidity. The independent variables were ownership type, hospital type, location, bed size, period of establishment, short-term liabilities to total assets, long-term liabilities to total assets, borrowings to total assets, fixed asset ration, net profit to total assets, operating margin to gross revenue, growth rate of net worth to total assets, total asset turnover, and business risk(volatility of profit). The major findings of this study were as follows. Trends of liquidity(current ratio, quick ratio) had been continuously decreased. Especially, There were very distinct decreasing trends of personal hospitals and less than 300beds, which weakened liquidity. The factors had significant effect on current ratio were short-term debt to total assets(-), fixed asset ratio(-), business risk(+). High short-term debt to total assets, high fixed asset ratio and high business risk significantly decreased in liquidity. The factors that significantly affected on quick ratio were short-term debt to total assets(-), borrowings to total assets(+), fixed asset ratio(-), business risk(+).

• Journal of the Korea Society for Simulation
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• v.20 no.2
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• pp.67-76
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• 2011

Order picking in automotive service parts warehouses is considered to be the most labor-intensive operation. Such warehouses contain hundreds of thousands of items, but normally 20% of products contribute to about 80% of turnover according to Pareto's 80-20 principle. Therefore most fast moving items are located near an outbound area which is called the "Golden Zone". Order picking routing efficiency is related to productivity and labor cost. However, most companies use simple methods. In this paper, we describe a series of computational experiments over a set of test cases where, we compared various previously existing routing heuristics to an optimal algorithm. We focus on examining the influence of the golden zone on the performance and selection of routing methods. The results obtained show that the optimal routing method increases the productivity at least 17.2%, and all the routing methods have better performance as the pick up rate from the golden zone increases.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.40 no.4
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• pp.230-236
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• 2017

The recent domestic construction market is in a difficult situation due to reduction of the government's SOC budget and new orders from public-sector, and the deterioration of housing supply situation in the private sector etc. In addition, the number of disasters in the construction industry has increased in recent years with 26,570 people (up 5.7% from the previous year) in 2016, unlike other industries that are in a declining trend. As such, the construction industry has unique characteristics and problems such as high industrial accidents rate, abnormal subcontracting structure, excessive working hours and work intensity. As a result, the construction workers have a lot of job stresses. Job stress has been recognized as one of the major causes of industrial accidents and many researches have been conducted on that. However, most of the researches were about the factors that induce job stress and how these factors affect disaster occurrence, job satisfaction, job performance, turnover intentions, and job exhaustion. The purpose of this study is to investigate the effect of positive psychological capital on job stress, which is emerging as a new human resources development paradigm useful in corporate management in order to find ways to reduce job stress. To do this, 347 data collected from construction workers in Daejeon, Sejong, and Chungcheong provinces were analyzed using statistical package(IBM SPSS 22) for basic statistical analysis, reliability analysis, and regression analysis. As a result, positive psychological capital has shown an alleviate effect on job stress. In particular, the higher the optimism, hope, and resiliency of positive psychological capital, the lower the job stress. However, the higher the self - efficacy, the higher the job stress.

• Journal of Radiation Protection and Research
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• v.41 no.3
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• pp.253-259
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• 2016

Background: This study investigated the effects of zoledronic acid (ZA) on radiation-induced bone loss in C3H/HeN mice. Materials and Methods: C3H/HeN mice were divided into sham control and three irradiated groups (3 Gy, gamma ray). The irradiated mice were treated for 12 weeks with vehicle, amifostine (intraperitoneal injection), or ZA (subcutaneous injection). Grip strength, uterus weight, and serum alkaline phosphatase (ALP), and tartrate-resistant acid phosphatase (TRAP) levels were measured. Tibiae were analyzed using micro-computed tomography. Results and Discussion: Treatment of ZA ($100{\mu}g{\cdot}kg^{-1}{\cdot}week^{-1}$) significantly preserved trabecular bone volume, trabecular thickness, trabecular number, trabecular separation, bone mineral density of proximal tibia metaphysic, and cortical bone volume, but did not alter the uterus weight of the mice. The administration of ZA for 12 weeks lowered serum ALP and TRAP levels in irradiated mice, suggesting that ZA can reduce the bone turnover rate in mice. No differences were apparent between the amifostine-treated group and the irradiation control group. Conclusion: The results indicate that ZA can prevent radiation-induced bone loss in mice.

• Convergence Security Journal
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• v.11 no.2
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• pp.55-64
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• 2011

This study is to investigate the relationship of the effect of the private security guard unethical work ethic on job attitude and customer service. We extracted about 450 people examples after the Selection of the private security guard's in active service in Seoul in 2010, and totally 412 people examples were used. This study carried out factorial analysis, reliability analysis, correlation analysis, multiple regression analysis and pass analysis using SPSSWIN 16.0. The followings are conclusions. First, unethical work ethic affects on job attitude partially. Namely, tampering with work and information leaks reduce job attitude. Also, information leaks increase company's turnover rate. Second, unethical work ethic has no effect on customer service. Third, job attitude affects on customer service partially. In other words, the organizational commitment improves the quality of service but decreases the customer-centered service. Fourth, unethical work ethic has an effect on job attitude and customer service indirectly.