• The Journal of the Korea Contents Association
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• v.12 no.6
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• pp.380-389
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• 2012

In this study, Systematic review and meta-analysis using the correlation coefficients was carried out to integrate precedent studies on factors affecting domestic occupational therapists' job stress. It aims at providing basic information resources of preventing and reducing stress of occupational therapists and effective counter-measurement to improve quality of occupational therapy and to establish efficient human resource management policy. Systematic review and meta-analysis were performed on eight thesis proven relevant to selection criteria in order to figure out correlation coefficients value by total, and factors correlation coefficients value. Also homogeneity test and publication bias test was performed too. The total correlation coefficients value of occupational therapists was .30 which was statistically significant. As to job stress factors, the organization related factor showed the highest correlation of coefficiency, followed by factors other than the organization related, physical environment, job related factor and personal factor. This research result can be used as a reference to prevent and reduce job stress of occupational therapists and to develop an effective measurement scheme.

• Strategy21
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• s.46
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• pp.123-157
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• 2020

This research focuses on one important type of non-traditional threat, maritime piracy, and tries to supplement previous research from the perspective of military power, especially naval power. When considering the elements of military power, naval power is a core independent variable to explain piracy incidents. Indeed, naval power can play a key role in solving piracy problems, since naval power is the only legitimate force to respond to piracy in the sea. It is natural that well equipped and trained naval power in the sea increases the probability of capturing pirates, which leads to increasing the costs of piracy and decreasing its occurrences. In addition, since naval combatant ships have more impressive weapons than those of pirate boats, just the presence of naval combatant ships could serve to deter piracy incidents in the sea. The main purpose of this research is finding the effectiveness of large multinational naval efforts to deter piracy incidents in Africa. With this research purpose, I analyze 771 piracy incidents that occurred in African states from 2009 to 2014. Furthermore, I include all 33 coastal states in Africa regardless of the experiences of piracy incidents in order to avoid selection bias, which is very common in quantitative-based piracy incidents research. The dependent variable of this research is frequency of maritime piracy incidents for a country-year and the independent variable is the number of multi-national naval warships that operate near Somalia. With this analysis, I find the large number of multi-state naval combatant ships are negatively related to piracy incidents. In other words, as a main means to counteract piracy incidents, multi-state naval combatant ships are conducive to reduce piracy incidents near Somalia, since it increases costs (being captured) of conducting piracy.

• Informatization Policy
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• v.21 no.2
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• pp.67-88
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• 2014

The research hypothesis of this paper is that education for smart device utilization has a positive effect on ability and utilization of smart devices for the disabled. The data for disabled of NIA's 2012 survey about digital divide is used, and the research method is "Heckman's 2-stage method" which considers the problem of selection bias. As a research result, this paper says that the disabled who had experience of education for smart device utilization have higher level of ability and utilization of smart devices. Also, a high level of education and family income, professional career and young generation have been very positive effect on the high level of ability and utilization of the disabled. The level of ability and utilization of the blind tend to be lower than those of the physically disabled. These results remind that the education for smart device utilization for the disabled is important and effective. And various contents and methods of education which are appropriate for the disability types should be developed.

• Archives of design research
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• v.19 no.2 s.64
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• pp.91-98
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• 2006

The product convergence and complex application environment raise the need of multi-modal interface which enables us to interact products through various human senses. The sense of vision has been used predominantly more than any other senses for the traditional and general information gathering situation, but in the future which will be developed based on the digital network technology, the practical use of the various senses will be desired for more convenient and rational usage of the information appliances. The sense of auditory which possibility of practical use is becoming higher than ever with the sense of vision, the possible usage will be developed broader and in the various ways in the future. Based on this situation, the characteristics of the written language and the colloquial language and the comparative analysis of the difference between male and female's reaction for each language were examined through this study. To achieve this purpose, the literature research about the diverse components of the language system was peformed. Then, some peculiar characters of the sense of vision and auditory were reviewed and the appropriate experimentation was planned and carried out. The result of the accomplished experimentation was examined by the objective analysis method. The main results of this study are as follows: first, the reaction time for written language is shorter than colloquial language, second, there is a partial difference between the male's and female's reaction for those two stimuli, third, there is no selection bias between the sense of sight and the sense of hearing. I think the continuous development of the broad and diverse ways of study for various senses is needed based on this study.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.19 no.1
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• pp.149-155
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• 2015

This paper proposes 5-MS/s 10-bit digital-to-analog converter(DAC) with the improved linearity. The proposed DAC consists of a 10-bit R-2R-based DAC, an output buffer using a differential voltage amplifier with rail-to-rail input range, and a band-gap reference circuit for the bias voltage. The linearity of the 10-bit R-2R DAC is improved as the resistor of 2R is implemented by including the turn-on resistance of an inverter for a switch. The output voltage range of the DAC is determined to be $2/3{\times}VDD$ from an rail-to-rail output voltage range of the R-2R DAC using a differential voltage amplifier in the output buffer. The proposed DAC is implemented using a 1-poly 8-metal 130nm CMOS process with 1.2-V supply. The measured dynamic performance of the implemented DAC are the ENOB of 9.4 bit, SNDR of 58 dB, and SFDR of 63 dBc. The measured DNL and INL are less than +/-0.35 LSB. The area and power consumption of DAC are $642.9{\times}366.6{\mu}m^2$ and 2.95 mW, respectively.

• Journal of Distribution Science
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• v.12 no.8
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• pp.113-121
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• 2014

Purpose - Recently, the number of corporations that practice environmental and social responsibility, besides engaging in traditional profit-seeking activities, has been growing steadily, as interest in Corporate Social Responsibility (CSR) is increasing. Recent research on CSR practices has identified the relationship between CSR activities and corporate value as one of the main issues in this respect. Considering that donations constitute a large proportion of a company's charitable activities, we considered the extent of donation expenses as a charitable activity in order to mitigate sample selection bias. Specifically, we analyzed the impact of donation expenses on firm value, while investigating if this impact varied in response to the level of corporate governance of firms. Research design, data, and methodology - We used non-financial firms listed on the Korean Stock Exchange, having their fiscal year end in December, and the sample period was 2006-2013. For the dependent variable, Tobin's q was used as the corporate value, and for the independent variable, donations were measured as the donation-expense-to-sales ratio. Corporate governance scores, as rated by the Korea Corporate Governance Service, were used to measure corporate governance levels because they consider the overall aspects of governance, including ownership structure, the board of directors, and the audit mechanism of individual companies. To examine the impact of donations on a company in relation to the level of corporate governance, we estimated regression models using the interaction terms of the governance dummy and donation variables. Then, we further estimated the regression models of two sub-samples that were classified according to the level of corporate governance. Similar to previous studies, the study uses variables that affect firm value, such as R&D expenditure, advertising expenses, EBITDA, debt-to-equity ratio, sales growth, company age, and company size as control variables. Results - The empirical results show that firm value significantly increased in response to an increase in donation expenses. Upon including the interaction terms of governance level dummy variables and donations, the coefficients of the interaction terms show significant positive values, while those of donation variables show significant negative values. In the strong governance sub-sample, the relationship between the donation expenses and corporate value was statistically positive (+) and significant. However, in the weak governance sub-sample, the relationship between the donation expenses and corporate value was statistically insignificant and negative (-). Conclusions - The empirical results suggest that donation expenses are significantly linked to an enhanced corporate value if firms have a good corporate governance structure. However, if the corporate governance structure is weak, the same relationship is not necessarily observed. The results of this study show that if a firm has high corporate governance, CSR practices enhance the company's reputation such that it has a positive (+) relationship with corporate value. If a firm has weak corporate governance, on the other hand, CSR practices are recognized as an agency cost and do not increase corporate value.

• Journal of Korean Neurosurgical Society
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• v.65 no.4
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• pp.539-548
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• 2022

Objective : Although full-endoscopic lumbar interbody fusion (Endo-LIF) has been tried as the latest alternative technique to minimally invasive transforaminal lumbar interobody fusion (MIS-TLIF) since mid-2010, the evidence is still lacking. We compared the clinical outcome and safety of Endo-LIF to MIS-TLIF for lumbar degenerative disease. Methods : We systematically searched electronic databases, including PubMed, EMBASE, and Cochrane Library to find literature comparing Endo-LIF to MIS-TLIF. The results retrieved were last updated on December 11, 2020. The perioperative outcome included the operation time, blood loss, complication, and hospital stay. The clinical outcomes included Visual analog scale (VAS) of low back pain and leg pain and Oswestry disability index (ODI), and the radiological outcome included pseudoarthosis rate with 12-month minimum follow-up. Results : Four retrospective observational studies and one prospective observational study comprising 423 patients (183 Endo-LIF and 241 MIS-TLIF) were included, and the pooled data analysis revealed low heterogeneity between studies in our review. Baseline characteristics including age and sex were not different between the two groups. Operation time was significantly longer in Endo-LIF (mean difference [MD], 23.220 minutes; 95% confidence interval [CI], 10.669-35.771; p=0.001). However, Endo-LIF resulted in less perioperative blood loss (MD, -144.710 mL; 95% CI, 247.941-41.478; p=0.023). Although VAS back pain at final (MD, -0.120; p=0.586), leg pain within 2 weeks (MD, 0.005; p=0.293), VAS leg pain at final (MD, 0.099; p=0.099), ODI at final (MD, 0.141; p=0.093) were not different, VAS back pain within 2 weeks was more favorable in the Endo-LIF (MD, -1.538; 95% CI, -2.044 to -1.032; p<0.001). On the other hand, no statistically significant group difference in complication rate (relative risk [RR], 0.709; p=0.774), hospital stay (MD, -2.399; p=0.151), and pseudoarthrosis rate (RR, 1.284; p=0.736) were found. Conclusion : Relative to MIS-TLIF, immediate outcomes were favorable in Endo-LIF in terms of blood loss and immediate VAS back pain, although complication rate, mid-term clinical outcomes, and fusion rate were not different. However, the challenges for Endo-LIF include longer operation time which means a difficult learning curve and limited surgical indication which means patient selection bias. Larger-scale, well-designed study with long-term follow-up and randomized controlled trials are needed to confirm and update the results of this systematic review.

• Knowledge Management Research
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• v.23 no.4
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• pp.177-205
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• 2022

Small- and medium-sized enterprises (SMEs) have strong incentives to engage in open innovation to enhance innovation efficiency and effectiveness due to their 'liability of smallness.' Previous research examined the performance effects of various open innovation practices, but whether coupled open innovation practices positively affect SMEs' firm performance is somewhat controversial. To resolve the issue, this study examined the effects of coupled open innovation activities on SMEs' firm performance using Heckman's two stage model to control endogeneity of the firms' self-selection bias in open innovation engagement. This study used the Korean Innovation Survey (KIS) 2020 collected by the Science and Technology Policy Institute (STEPI), and tested the effects of SMEs' coupled open innovation activities, R&D and non-R&D cooperation, on their innovative and financial performance indicators. The results showed that SMEs' R&D cooperation positively affects the new-to-market (NTM) product innovation only. Moreover, SMEs' non-R&D cooperation has positive effects on the product innovation, business process innovation, new-to-the-market product innovation, and new-to-firm (NTF) product innovation. However, the results showed that both R&D and non-R&D innovation cooperation activities have no significant effects on SMEs' financial performance indicators. This study contributes to research on SMEs' open innovation and provides insights for SMEs' managers and policymakers.

• The Journal of Internal Korean Medicine
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• v.44 no.3
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• pp.387-401
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• 2023

Objective: This study was conducted to investigate the preventive effect of herbal medicines on restenosis after percutaneous coronary intervention (PCI) by reviewing randomized controlled trials (RCTs). Methods: RCTs were searched for herbal medicine treatment after PCI using eight online databases (PubMed, CNKI, Wanfang, J-STAGE, OASIS, ScienceON, KTKP, and KISS). Studies that confirmed restenosis through coronary angiography at follow-up were selected according to the inclusion and exclusion criteria. The primary outcome was the restenosis rate, and the secondary outcome was the angina recurrence rate. Data were extracted from the final selected studies according to the research methodology and then analyzed with Review Manager 5.4.1. Study quality was assessed using Cochrane's risk-of-bias (RoB) tool. Results: Of the 252 papers obtained through the primary search, nine studies that met the selection criteria were finally selected. In these nine studies, herbal medicine combined with western medicine was used for the experimental group, and western medicine treatment was used alone for the control group. The meta-analysis result revealed that the restenosis rate and angina recurrence rate were significantly lower in the experimental group than in the control group (RR=0.34, 95% CI: 0.22-0.53, p<0.00001, I²=0% and RR=0.47, 95% CI: 0.29-0.78, p=0.004, I²=0%, respectively). Furthermore, the quality of studies assessed by Cochrane's RoB was low. Conclusions: This study showed that the combined treatment of herbal medicine and western medicine was effective in preventing restenosis and angina after PCI. As the number of papers included in this study was small, a large number of high-quality clinical studies should be considered in the future.

• Korean Journal of Agricultural and Forest Meteorology
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• v.12 no.1
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• pp.36-44
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• 2010

In order to rehabilitate forest sites damaged by wildfire via natural or artificial restoration, it is important to determine right tree species, which can acclimate to biogeoclimatic environment at the sites. The objectives of this study were to develop site index equation of different tree species for estimating forest productivity and to provide information on species selection for post-wildfire restoration. Site index equation was developed based on environmental information from wildfire damaged areas in Gangneung, Goseong, Donghae, and Samcheok, where were located in east coastal areas of South Korea. Despite the small numbers (4~5) of environmental variables used for the development of the site index equations, statistical analysis (e.g. mean difference, standard deviation of difference, and standard error of difference) showed relatively low bias and variation, suggesting that those equations can provide relatively high capability of estimation and practical applicability with high effectiveness. The small numbers of the variables enabled the model to be applied in a wide range of usages including determination of appropriate tree species for post-wildfire restoration. The estimation of forest site productivity showed the possibility of large distribution in east coastal region as the best site for Korean ash (Fraxinus rhynchophylla) and original oak (Quercus variabilis) that can be used for firebreak in the region. These results imply that damages by forest fire can be reduced significantly by replacing existing pure coniferous forests in the area with ones dominated by broad-leaved deciduous stands, which can play an important role as fire break and/or prevent a transition from surface fire to crown fire.