• Journal of Labour Economics
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• v.26 no.2
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• pp.1-30
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• 2003

The recent experience about self-employment shows three main trends: first, its share out of the total workers has steadily increased, recording 37.6% in 2001, implying its prevalence and importance; second, its share out of male workers has caught up female workers', implying its importance to males as well as females; and finally, during the recent Economic Crisis when there was mass layoff and large scale bankruptcy, its share rapidly increased, reflecting its role of a buffer to economic fluctuation. However, there have been few studies on self-employment, mainly focusing on what makes someone choose it as an alternative to being employed. This study analyzes the determinants of the duration to terminate self-employment, by applying the proportional hazard model to the Korea Labor and Income Panel Survey(KLIPS) by the Korea Labor Institute. The KLIPS started the first wave in 1998 with the 5,000 household sample (and about 12,000 individual sample of household members aged 15 and more). In this study, the first four waves are used for analysis. The average duration of 5,357 spells of self-employment is 130 months. It shows slight difference between males(124 months) and females(138 months) while it widely ranges over industries (296 months for agriculture industry while 50 months for restaurant and hotel industry). Estimates of the proportional hazard model of the self-employment duration show that females are more likely to terminate self-employment while it is not statistically significant. The effect of age at starting self-employment on the hazard shows the inverse V-shape, which implies that, until a certain age(47 years), the hazard become higher as aging while, since then, it become lower as aging. The level of education has a positive effect on the hazard, implying that more education is related to the higher probability to be employed. The measures of economic performances, annual sales and earnings, are positively related to continuing self-employment while hardship at the start of self-employment measured by several ways has a negative effect. Training before opening business has a positive effect on keeping on self-employment and its effects are different over its providers, significantly positive for public providers while insignificant for private providers. More and further research on self-employment is urgent in the rapidly ageing society. To help workers to be self-employed, more public assistance is necessary for education, training, financing, marketing, management, and human resource management in order to make the olders consider self-employment as a good alternative rather than an inevitable one.

• Journal of Korea Water Resources Association
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• v.49 no.5
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• pp.439-450
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• 2016

For the design of infrastructures controlling the flood events at ungauged basins, this study tries to find the regional flood frequencies using peak flow data generated by the spatial extension of flood records. The Chungju Dam watershed is selected to validate the possibility of regional flood frequency analysis using the spatially extended flood data. Firstly, based on the index flood method, the flood event data from the spatial extension method is evaluated for 22 mid/smaller sub-basins at the Chungju Dam watershed. The homogeneity of the Chungju dam watershed was assessed in terms of the different size of watershed conditions such as accumulated and individual sub-basins. Based on the result of homogeneity analysis, this watershed is heterogeneous with respect to individual sub-basins because of the heterogeneity of rainfall distribution. To decide the regional probability distribution, goodness-of fit measure and weighted moving averages method from flood frequency analysis were adopted. Finally, GEV distribution was selected as a representative distribution and regional quantile were estimated. This research is one step further method to estimate regional flood frequency for ungauged basins.

• Journal of Labour Economics
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• v.38 no.4
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• pp.1-29
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• 2015

The Individual Retirement Pension (IRP) enables workers to continuously receive a retirement pension even when workers change their jobs in different companies and so it performs a bridge fund as the complimentary living expenses until they receive government public pension. Although the Korean government has forced workers to maintain an IRP account until their retirement age and to close their accounts only when they want to do so, it is not clear to measure its really effectiveness and, in fact, most of IRP accounts have been terminated immediately after the changes of their jobs. In this respect, IRP has not performed the bridge role for the future retirement pension income. We provide an economic decision-making model of both government and workers, where the retirement benefits related with the IRP are explicitly considered. Our model is required to select specific severance pay systems to maximize the income security and stability for their future old ages. It is concluded that the need of workers on the severance pay system is automatically revealed into the switch to IRP when workers are out from their current jobs, which is equivalent to the effect of gradually unifying the dual system of the retirement payment. In additoin, our empirical data indicates the relatively higher probability of termination on IRP for the older male workers having the more retirement deposit.

• Science of Emotion and Sensibility
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• v.10 no.4
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• pp.511-521
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• 2007

It is very important that design based on preference of consumers who continuously change. Therefore, the method that can decide on the design concept which a consumer can prefer in future points of time that a design is released is necessary. There may be various ways to decide a design concept, but trend analysis is one of the best ways to be able to satisfy consumer preference. The purpose of this study is to provide a process that can give a direction of MP3 player design oriented consumer emotion. For the purpose, we considered about trend analysis as the ways that can present the design direction that can grasp a change of continuous preference, and a consumer can prefer with early bases in future points of time of a consumer. In this empirical research, we decided on design elements and levels of the elements after collecting 228 MP3 players released from 2000 to 2007, and carried out trend analysis through homogeneity analysis by SPSS program. In the result, we knew that future consumers also will regard emotional experience consumption as important. So, MP3 player design will be developed into consumer emotion-oriented design. We predict 4 trends for a future MP3 player design. 1. Development of high-priced MP3 player with various multimedia functions. 2. Development of MP3 player with basic functions. 3. Development of new convergence products with MP3 function. 4. Development of new MP3 player based on flash memory. If designers can infer a future MP3 player design from this design trend results, the probability that can occupy competitive advantage in their competitions will be high. Therefore this study can be useful.

• Atmosphere
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• v.21 no.2
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• pp.131-142
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• 2011

Spectral solar irradiances were observed using a visible and UV Multi-Filter Rotating Shadowband Radiometer on the rooftop of the Science Building at Yonsei University, Seoul ($37.57^{\circ}N$, $126.98^{\circ}E$, 86 m) during one year period in 2006. 1-min measurements of global(total) and diffuse solar irradiances over the solar zenith angle (SZA) ranges from $20^{\circ}$ to $70^{\circ}$ were used to examine the effects of clouds and total optical depth (TOD) on enhancing four solar irradiance components (broadband 395-955 nm, UV channel 304.5 nm, visible channel 495.2 nm, and infrared channel 869.2 nm) together with the sky camera images for the assessment of cloud conditions at the time of each measurement. The obtained clear-sky irradiance measurements were used for empirical model of clear-sky irradiance with the cosine of the solar zenith angle (SZA) as an independent variable. These developed models produce continuous estimates of global and diffuse solar irradiances for clear sky. Then, the clear-sky irradiances are used to estimate the effects of clouds and TOD on the enhancement of surface solar irradiance as a difference between the measured and the estimated clear-sky values. It was found that the enhancements occur at TODs less than 1.0 (i.e. transmissivity greater than 37%) when solar disk was not obscured or obscured by optically thin clouds. Although the TOD is less than 1.0, the probability of the occurrence for the enhancements shows 50~65% depending on four different solar radiation components with the low UV irradiance. The cumulus types such as stratoculmus and altoculumus were found to produce localized enhancement of broadband global solar irradiance of up to 36.0% at TOD of 0.43 under overcast skies (cloud cover 90%) when direct solar beam was unobstructed through the broken clouds. However, those same type clouds were found to attenuate up to 80% of the incoming global solar irradiance at TOD of about 7.0. The maximum global UV enhancement was only 3.8% which is much lower than those of other three solar components because of the light scattering efficiency of cloud drops. It was shown that the most of the enhancements occurred under cloud cover from 40 to 90%. The broadband global enhancement greater than 20% occurred for SZAs ranging from 28 to $62^{\circ}$. The broadband diffuse irradiance has been increased up to 467.8% (TOD 0.34) by clouds. In the case of channel 869.0 nm, the maximum diffuse enhancement was 609.5%. Thus, it is required to measure irradiance for various cloud conditions in order to obtain climatological values, to trace the differences among cloud types, and to eventually estimate the influence on solar irradiance by cloud characteristics.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.30 no.5
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• pp.371-380
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• 2017

The risk-targeted seismic design concept was first included in ASCE/SEI 7-10 to address problems related to the uniform-hazard based seismic concept that has been constructed without explicitly considering probabilistic uncertainties in the collapse capacities of structures. However, this concept is not yet reflected to the current Korean building code(KBC) because of insufficient strong earthquake data occurred at the Korean peninsula and little information on the collapse capacities of structures. This study evaluates the risk-targeted seismic performance of steel ordinary concentrically braced frames(OCBFs). To do this, the collapse capacities of prototype steel OCBFs are assessed with various analysis parameters including building locations, building heights and soil conditions. The seismic hazard curves are developed using an empirical spectral shape prediction model that is capable of reflecting the characteristics of earthquake records. The collapse probabilities of the prototype steel OCBFs located at the Korean major cities are then evaluated using the risk integral concept. As a result, analysis parameters considerably influence the collapse probabilities of steel OCBFs. The collapse probabilities of taller steel OCBFs exceed the target seismic risk of 1 percent in 50 years, which the introduction of the height limitation of steel OCBFs into the future KBC should be considered.

• Informatization Policy
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• v.27 no.1
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• pp.72-91
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• 2020

In this study, we classified SNS into open and closed types, and empirically examined in which SNS activity the privacy paradox holds. The idea comes from the argument that privacy paradox may be observed differently in the open SNS, which is more vulnerable to the leakage of personal information due to public profiles, and the closed SNS, which is relatively less vulnerable by limiting the range of acquaintances, The results of the empirical analysis are as follows. First, in case of SNS usage, the privacy paradox holds in the overall SNS activities, but different conclusions are drawn according to open and closed SNS. In particular, it is found that as privacy concerns increase, individuals respond in a reasonable and desirable way to reduce SNS activity in the open SNS, which is more susceptible to infringement. Second, in the case of SNS activity intensity, (i) heavy users are more seriously aware of the probability of privacy infringement than light users, so there is a reasonable response to reducing the intensive margin with increasing privacy concerns, and (ii) this tendency is more clearly observed in open SNS, which is more vulnerable to privacy infringement. Accordingly, insisting that the privacy paradox is empirically established by observing only the overall SNS activities without distinguishing them into open and closed SNS may be interpreted as a "Fallacy of Composition."

• The Korean Journal of Applied Statistics
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• v.30 no.4
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• pp.539-553
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• 2017

We propose a multi-state model to analyze semi-competing risks data with interval-censored or missing intermediate events. This model is an extension of the three states of the illness-death model: healthy, disease, and dead. The 'diseased' state can be considered as the intermediate event. Two more states are added into the illness-death model to incorporate the missing events, which are caused by a loss of follow-up before the end of a study. One of them is a state of the lost-to-follow-up (LTF), and the other is an unobservable state that represents an intermediate event experienced after the occurrence of LTF. Given covariates, we employ the Lin and Ying additive hazards model with log-normal frailty and construct a conditional likelihood to estimate transition intensities between states in the multi-state model. A marginalization of the full likelihood is completed using adaptive importance sampling, and the optimal solution of the regression parameters is achieved through an iterative quasi-Newton algorithm. Simulation studies are performed to investigate the finite-sample performance of the proposed estimation method in terms of empirical coverage probability of true regression parameters. Our proposed method is also illustrated with a dataset adapted from Helmer et al. (2001).

• Journal of National Security and Military Science
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• s.5
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• pp.241-280
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• 2007

This study examines the relationship of the industry-specific factors that effect innovation of manufacturing technology and the market share within the defense industry. Since the establishment of the basic defense industry framework in 1973, there were numerous interactions of the industry-specific factors of the defense industry structure with the technological innovation and market organization of the defense industry. During last three decades, the domestic defense industry has achieved the considerable level but the framework of the basic system has not developed much in areas of the military science and the defense manufacturing technology. Industry-specific factors were formed in the process and appeared in a variety of behavioral characteristics as subsystems. Currently, there IS a growing trend where the management of defense industry is gradually deteriorating due to limitation of the domestic industry-specific factor (e.g. defense technologies, amount of demand, etc.). If there is a prominent imbalance of the industry-specific factors. it can trigger the potential problem of conflict, lack of cooperation and control, slowing the growth of the manufacturing technology thereby diminishing the market and deteriorating the defense supply/demand relationship. In a research conducted by Joe S. Bain, Bain analyzed the relationship of the traditional industrial organization where industry-specific factor(S) not only impacts the conductor(C). And, conductor(C) influences the shaping of the performance(P) of relationship of the traditional industrial organization. Consequently, the researcher has identified the demand monopoly, barriers to entry, and market competition with comparison of defense industry issues. These defense issues were three industry-specific factors identified, which are 1) The demand monopoly and The entry barriers to new market competition, 2) the industrial technical factor to a production technical competitiveness and a market sharing competitiveness, 3) the probability factor to revolution for military affairs(RMA) and a R&D production. According to baseline with these factors, the following research model is established from the special companies group(Group A), the systematization companies group(Group B), and the general companies group(Group 0. The hypothesis is that if there are more industry-specific factors, then there will be more relationships of defense industry relation statutes. This research is an empirical study on the relationship that the industry specific factors effects the innovation of manufacturing technology and the shaping of the market in the defense industry. Moreover, the existing models to evaluate the industry specific factors of the defense industry IS much to be desired with the controlled statistical analysis of the result. It is vital to study on current situation with suggesting alternative strategy to the efficient strategy. The descriptive analysis approach analysis is conducted with SPSSWIN to conduct reliability test, factor analysis, correlation analysis, cross-tabulation analysis, one-way ANOVA, and multiple regression analysis. However, there were some limitations of the survey such as the rigidity of concept about the technical factors and various market management factors. The wishes is that the decision-maker could be utilized these defence industrial factors to formulate efficient defence policy and strategy in the future.

• Journal of the Ergonomics Society of Korea
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• v.30 no.1
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• pp.99-108
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• 2011

Almost all companies have paid much attention to the safety management ranging from maintenance to operation even at the stage of designing in order to prevent accidents, but fatal accidents continue to increase throughout the world. In particular, it is essential to systematically prevent such fatal accidents as fire, explosion or leakage of toxic gas at factories in order to not only protect the workers and neighbors but also prevent economic losses and environmental pollution. Though it is well known that accident probability is very low in NPP(Nuclear Power Plants), the reason why many researches are still being performed about the accidents is the results may be so severe. HRA is the main process to make preparation for possibility of human error in designing of the NPP. But those techniques have some problems and limitation as follows; the evaluation sensitivity of those techniques are out of date. And the evaluation of human error is not coupled with the design process. Additionally, the scope of the human error which has to be included in reliability assessment should be expanded. This work focuses on the coincidence of human error and mechanical failure for some important performance shaping factors to propose a method for improving safety effectively of the process industries. In order to apply in these purposes into the thesis, I found 63 critical Performance Shaping Factors of the eight dimensions throughout studies that I executed earlier. In this study, various analysis of opinion of specialists(Personal Factors, Training, Knowledge or Experience, Procedures and Documentation, Information, Communications, HMI, Workplace Design, Quality of Environment, Team Factors) and the guideline for construction of PSF were accomplished. The selected method was AHP which simplifies objective conclusions by maintaining consistency. This research focused on the implementation process of PSF to evaluate the process of PSF at each phase. As a result, we propose an evaluation model of PSF as a tool to find critical problem at each phase and improve on how to resolve the problems found at each phase. This evaluation model makes it possible to extraction of PSF succesfully by presenting the basis of assessment which will be used by enterprises to minimize the trial and error of construction process of PSF.