• 한국정보디스플레이학회:학술대회논문집
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• 2005.07b
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• pp.1203-1206
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• 2005

Electron temperature and plasma density in coplanar alternating-current plasma display panels (AC-PDP's) have been experimentally investigated in accordance with discharge time by a micro-probe in this experiment. The resolution of a step mortor to move in micro-Langmuir probe is 10um.[1-3] The used gas in this experiment is He-Ne-Xe (4%) mixure gas. And sustain voltage is 320V which is above of firing voltage for degradation. The electron temperature and plasma density can be obtained from current-voltage (I-V) characteristics of micro Langmuir probe, in which negative to positive bias voltage was applied to the probe. And Efficiency is calculated by formula related discharge power and light emission. Those experiments operated as various discharge time ($0{\sim}72$ Hours). As a result of this experiment, Electron Temperature was increased from 2eV to 5eV after discharge running time of 20 hours and saturates beyond 20 hours. The plasma density is inversely proportional to the square root of electron temperature. So the plasma density was decreased from $1.8{\times}10^{12}cm^{-3}$ to $8{\times}10^{11}cm^{-3}$ at above discharge running time. And the Efficiency was reduced to 70% at 60hours of discharge running time.

• Asian Pacific Journal of Cancer Prevention
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• v.16 no.12
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• pp.5125-5135
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• 2015

Background: Total fat intake may be associated with increased risk of breast cancer, and fish oil has been suggested as a protection factor to breast cancer. But the effect of vegetable oils is inconclusive. We aimed to investigate the association with high vegetable oils consumption and breast cancer risk, and evaluated their dose-response relationship. Design: We systematically searched the MEDLINE, EMBASE, Cochrane databases, and CNKI updated to December 2014, and identified all observational studies providing quantitative estimates between breast cancer risk and different vegetable oils consumption. Fixed or random effect models were used to estimate summary odds ratios for the highest vs. lowest intake, and dose-response relationship was assessed by restricted cubic spline model and generalized least-squares trend (GLST) model. Results: Five prospective cohort studies and 11 retrospective case-control studies, involving 11,161 breast cancer events from more than 150,000 females, met the inclusion criteria. Compared with the lowest vegetable oils consumption, higher intake didn't increased the risk of breast cancer with pooled OR of 0.88 (95% CIs:0.77-1.01), and the result from dose-response analyses didn't show a significant positive or negative trend on the breast cancer risk for each 10g vegetable oil/day increment (OR=0.98, 95% CIs: 0.95-1.01). In the subgroup analyses, the oils might impact on females with different strata of BMI. Higher olive oil intake showed a protective effect against breast cancer with OR of 0.74 (95% CIs: 0.60-0.92), which was not significant among the three cohort studies. Conclusions: This meta-analyses suggested that higher intake of vegetable oils is not associated with the higher risk of breast cancer. Olive oil might be a protective factor for the cancer occurrence among case-control studies and from the whole. Recall bias and imbalance in study location and vegetable oils subtypes shouldn't be ignored. More prospective cohort studies are required to confirm the interaction of the impact of vegetable oils on different population and various cancer characteristic, and further investigate the relationship between different subtype oils and breast cancer.

• Journal of Distribution Science
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• v.13 no.10
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• pp.73-82
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• 2015

Purpose - This paper aims to investigate whether information asymmetry could explain capital structures in Korean corporations. According to Myers (1984), firms prefer internal funding to external financing due to the costs associated with information asymmetry. When external financing is necessary, firms prefer to issue debt rather than equity by the same reasoning. Since Shyam-Sunder and Myers (1999), numerous studies continue to debate the validity of the theory. In this paper, we show how the theory depends on assumptions and incorporated variables. We hope our investigation can provide helpful implications regarding capital structure, information asymmetry, and other firm characteristics. Specifically, our empirical results are complementary to the analysis of Son and Lee's (2015), a recent study that examines the pecking order theory prediction for Korean retail firms. Research design, data, and methodology - We test empirical models that are some variants of model used in Shyam-Sunder and Myers (1999). The financial and accounting data are provided by WISEfn for the firms listed on the KOSPI during 1990 to 2013. Bond ratings are supplied by the Korea Investor Service (KIS). We take into account the heterogeneity in debt capacity; a firm's debt capacity is measured by using the method of Lemmon and Zender (2010) based on its bond ratings. Finally, we estimate empirical models suggested by Shyam-Sunder and Myers (1999), Frank and Goyal (2003), and Lemmon and Zender (2010). Results - First, we find that Shyam-Sunder and Myers' (1999) prediction fails to explain total debt changes of Korean firms. Second, we find a non-monotonic relationship between total debt changes and financial deficits with respect to debt capacity. This contradicts the prediction of Lemmon and Zender (2010) that argues the pecking order theory survives with a monotonically increasing relationship. Third, we estimate a negative correlation coefficient between financial deficit and current debt changes. The result is the complete opposite of the prediction of Lemmon and Zender (2010). Finally, we also confirm the non-monotonic relationship between non-current debt changes and financial deficits with respect to debt capacity. Yet, the slope of coefficient is smaller than that of total debt change case. Indeed, the results are, to some extent, consistent with the prediction of pecking order theory, if we exclude the mid-debt capacity firms. Conclusions - Our empirical results complementary to the analysis of Son and Lee (2015), a recent study focusing on capital structure in Korean retail firms; their paper suggests interesting topics regarding capital structure, information asymmetry, and other firm characteristics in Korean corporations. Contrary to Son and Lee (2015), our results show that total debt changes and current debt changes are inconsistent with the prediction of Shyam-Sunder and Myers (1999). However, similar to Son and Lee (2015), non-current debt changes are consistent with the pecking order prediction, in the case of excluding the mid-level debt capacity firms. This contrast allows us to infer that industry characteristics significantly affect the validity of the pecking order prediction. Further studies are needed to analyze the economics behind this phenomenon, which is beyond the scope of our paper. In addition, the estimation bias potentially matters regarding the firm-level debt capacity calculation. We also reserve this topic for future research.

• Journal of Korean Society for Geospatial Information Science
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• v.20 no.4
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• pp.29-36
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• 2012

In order to create a wind resource map, we need wind data, contour map and roughness map. Moving Filter technique was applied to Udo of Jeju Island to improve the accuracy and efficiency of creating roughness map based on the Land Cover Map of the Ministry of Environment. The Land Cover Map was simplified using moving filtering, and the roughness map was created with this Land Cover Map. The wind resource map was created using this roughness map. Finally, we verified the validity and application of moving filter technique for wind resource map. As a result, the wind map which was created using the roughness map with moving filtering showed bias values which were all negative. It means the wind map is underestimated to values of wind energy and RMSE values were also from 0.0237m/s to 0.0253m/s at 50m height. In other words, estimation of wind resource using image filtering provides reliable results at 80m height typically when the wind turbine is installed. Finally, we found that image filtering technique is very useful tool to make wind resource map.

• Journal of Environmental Science International
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• v.15 no.8
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• pp.701-718
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• 2006

The average ratio of the daily UV-B to total solar (75) irradiance at Busan (35.23$^{\circ}$N, 129.07$^{\circ}$E) in Korea is found as 0.11%. There is also a high exponential relationship between hourly UV-B and total solar irradiance: UV-B=exp (a$\times$(75-b))(R$^2$=0.93). The daily variation of total ozone is compared with the UV-B irradiance at Pohang (36.03$^{\circ}$N, 129.40$^{\circ}$E) in Korea using the Total Ozone Mapping Spectrometer (TOMS) data during the period of May to July in 2005. The total ozone (TO) has been maintained to a decreasing trend since 1979, which leading to a negative correlation with the ground-level UV-B irradiance doting the given period of cloudless day: UV-B=239.23-0.056 TO (R$^2$=0.52). The statistical predictions of daily total ozone are analyzed by using the data of the Brewer spectrophotometer and TOMS in East Asia including the Korean peninsula. The long-term monthly averages of total ozone using the multiplicative seasonal AutoRegressive Integrated Moving Average (ARIMA) model are used to predict the hourly mean UV-B irradiance by interpolating the daily mean total ozone far the predicting period. We also can predict the next day's total ozone by using regression models based on the present day's total ozone by TOMS and the next day's predicted maximum air temperature by the Meteorological Mesoscale Model 5 (MM5). These predicted and observed total ozone amounts are used to input data of the parameterization model (PM) of hourly UV-B irradiance. The PM of UV-B irradiance is based on the main parameters such as cloudiness, solar zenith angle, total ozone, opacity of aerosols, altitude, and surface albedo. The input data for the model requires daily total ozone, hourly amount and type of cloud, visibility and air pressure. To simplify cloud effects in the model, the constant cloud transmittance are used. For example, the correlation coefficient of the PM using these cloud transmissivities is shown high in more than 0.91 for cloudy days in Busan, and the relative mean bias error (RMBE) and the relative root mean square error (RRMSE) are less than 21% and 27%, respectively. In this study, the daily variations of calculated and predicted UV-B irradiance are presented in high correlation coefficients of more than 0.86 at each monitoring site of the Korean peninsula as well as East Asia. The RMBE is within 10% of the mean measured hourly irradiance, and the RRMSE is within 15% for hourly irradiance, respectively. Although errors are present in cloud amounts and total ozone, the results are still acceptable.

• 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.

• The Journal of Korean Association of Computer Education
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• v.23 no.1
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• pp.63-75
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• 2020

From the perspective of compliance with security policies by members of the organization, which is a major cause of security incidents, this study presented biased thinking as factors that affect compliance with security policies and verified the following: First, the impact of biased thinking on security policies on compliance with security policies is verified. Second, the participation of management, perceived risk, education and punishment of management will verify the adjustment effect of increasing or decreasing biased thinking. Finally, we have verified that compliance attitudes have a significant impact on compliance behavior. To this end, 157 people were surveyed, statistical analysis of research models and structural equations, and conformity analysis were conducted. Studies have shown that biased thinking has a negative effect on the attitude of compliance with information security. In addition, it was analyzed that the attitude of compliance with information security policy increases policy compliance behavior. On the other hand, the higher the perceived risk of information security, the lower the bias was the adjustment effect, but management's participation, education and punishment were found to have no adjustment effect.

• Parasites, Hosts and Diseases
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• v.53 no.5
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• pp.553-559
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• 2015

Research on micro-level assessment of the changes of socio-economic status following health interventions is very scarce. The use of household asset data to determine wealth indices is a common procedure for estimating socio-economic position in resource poor settings. In such settings information about income is usually lacking, and the collection of individual consumption or expenditure data would require in-depth interviews, posing a considerable risk of bias. In this study, we determined the socio-economic status of 213 households in a community population in an island in the north-western Tanzania before and 3 year after implementation of a participatory hygiene and sanitation transformation (PHAST) intervention to control schistosomiasis and intestinal worm infections. We constructed a household 'wealth index' based housing construction features (e.g., type of roof, walls, and floor) and durable assets ownership (e.g., bicycle, radio, etc.). We employed principal components analysis and classified households into wealth quintiles. The study revealed that asset variables with positive factor scores were associated with higher socio-economic status, whereas asset variables with negative factor scores were associated with lower socio-economic status. Overall, households which were rated as the poorest and very poor were on the decrease, whereas those rated as poor, less poor, and the least poor were on the increase after PHAST intervention. This decrease/increase was significant. The median shifted from -0.4376677 to 0.5001073, and the mean from -0.2605787 (SD; 2.005688) to 0.2605787 (SD; 1.831199). The difference in socio-economic status of the people between the 2 phases was highly statistically significant (P<0.001). We argue that finding of this study should be treated with caution as there were other interventions to control schistosomiasis and intestinal worm infections which were running concurrently on Kome Island apart from PHAST intervention.

• Asia pacific journal of information systems
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• v.23 no.4
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• pp.129-149
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• 2013

According to the development of new Information Technologies, firms consistently invest a significant amount of money in IT activities, such as establishing internal and external information systems. However, several anti-Information activities-such as hacking, leakage of information and system destruction-are also rapidly increasing, thus many firms are exposed to direct and indirect threats. Therefore, firms try to establish information security systems and manage these systems more effectively via an enterprise perspective. However, stakeholders or some managers have negative opinions about information security systems. Therefore, in this research, we study the relationship between multibusiness firms' performance and information security systems. Information security indicates physical and logical correspondence of information system department against threats and disaster. Studies on information security systems suggested frameworks such as IT Governance Cube and COBIT Framework to identify information security systems. Thus, this study define that information security systems is a controlled system on enterprise IT process and resource on IT Governance perspective rather than independent domain of IT. Thus, Information Security Systems should be understood as a subordinate concept of IT and business processes. In addition, this study incorporates information capability to information security system literature to show the positive relationship between Information Security Systems and Corporate Performance. The concept of information capability suggested that an interaction of human, information, technical and an effect on corporate performance using three types of capability (IT Practice, Information Management Practice, Information Behaviors and Values). Information capability is about firms' capability to manage IT infrastructure and information as well as individual employees who use IT infrastructure and information. Thus, this study uses information capability as a mediating variable for the relationship between information security systems and firms' performance. To investigate the relationship between Information Security Systems and multibusiness firms' performance, this study extends the IT relatedness concept into Information Security Systems. IT relatedness provides understanding of how corporations cope with conflicts between headquarters and business units to create a synergy effect and achieve high performance using IT resources. Based on the previous literature, this study develops the IT Security Relatedness model. IT Security Relatedness is our main independent variable, while Information Capability and Information Security Performance are mediating variables. To control for the common method bias, we collect each multibusiness firm's financial performance and use it as our dependent variable. We find that Information Security Systems influence Information Capability and Information Security Performance positively, and these two variables consequently influence Corporate Performance positively. In addition, this result indirectly shows that corporations under a multibusiness environment can obtain synergy effects using the integrated Information Security Systems. This positive impact of Information Security Systems on multibusiness firms' performance has an important implication to various stakeholders. Therefore, multibusiness firms need to establish Information Security Systems to achieve better financial performance.

• The Journal of the Korea Contents Association
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• v.21 no.11
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• pp.320-332
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• 2021

This paper investigates the influence of stock-level left-tail risk, which is defined using Value-at-Risk(VaR) estimates of past one-year daily stock returns, in the expected stock returns in the Korean stock market. Our results are summarized as follows: First, monthly-constructed zero-cost portfolios that buy (shortsell) the highest (lowest) left-tail risk decile in the previous month exhibit an average monthly return (called left-tail risk premium) of -2.29%. Second, Fama-MacBeth cross-sectional regressions suggest that left-tail risk in the previous month shows significant and negative explanatory power over return in this month, after controlling for various firm characteristics such as firm size, B/M, market beta, liquidity, maximum daily return, idiosyncratic volatility, and skewness. Third, the stocks with larger recent month loss have lower returns in the next month. Fourth, the magnitude of left-tail risk premium is negatively related with lagged market-level volatility. These results support the hypothesis from a perspective of behavioral finance that the overpricing of stocks with left-tail risk is attributed to the investors' underreaction to it.