• The Korean Journal of Applied Statistics
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• v.25 no.6
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• pp.933-945
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• 2012

In this paper we used the KLIPS(Korean Labor and Income Panel tudy) data that surveyed from 2006(wave 9) to 2009(wave 12). Other previous studies are concerned with the panel attrition in the early wave, but this study classifies the response pattern and investigates some factors that influence panel attrition when the panel tends to stabilize. It was revealed that panel attrition was influenced by relocation and housing type through the logit model. Besides it was appeared that panel attrition was affected by the monthly living expenses and the overall household income through the decision tree.

• IEMEK Journal of Embedded Systems and Applications
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• v.18 no.1
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• pp.9-17
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• 2023

This paper relates to the development of a device for measuring the efficiency of a solar panel based on a variable constant current, and proposed a standard for reuse of the solar panel. By applying a variable constant current circuit to a solar panel efficiency measuring device, it was easy to apply a maximum power point tracking (MPPT) algorithm. In addition, a load dispersion method was applied to measure the efficiency of a high-capacity solar panel. and it is possible to solve a problematic thermal runaway during a MOSFET parallel operation by applying the load dispersion method. As a result of the experiment, the solar panel efficiency measuring device was able to accommodate a large solar panel of 350W, which is the maximum measurement goal. In this paper, the validity was confirmed through the 310W solar panel efficiency measurement experiment collected after removal.

• Journal of the Korean Wood Science and Technology
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• v.45 no.4
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• pp.444-455
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• 2017

This study was conducted to evaluate the effect of panel density and resin content on properties of medium density fiberboard (MDF) to obtain some insights on MDF properties as a function of panel density and resin content. MDF panels with different panel densities such as 650, 700, 750 and $800kg/m^3$ were manufactured by adjusting the amount of wood fibers in the mat forming. MDF panels were also fabricated by spraying 8, 10, 12, and 14% of urea-formaldehyde (UF) resins onto wood fibers in a drum-type mechanical blender to fabricate MDF panels with a target density of $650kg/m^3$. As the panel density and resin content increased, the internal bonding (IB) strength of MDF panel consistently increased. Modulus of rupture (MOR), modulus of elasticity (MOE) and screw withdrawal resistance (SWR) had a similar trend to the IB strength. In physical properties, thickness swelling (TS) and water absorption (WA) decreased with an increase in both panel density and resin content. In addition, the formaldehyde emission (FE) which increased as the panel density and resin content became greater. In overall, the panel density of MDF had more significant effect than the resin content in all properties of MDF panels, indicating that it was better to adjust the panel density rather than the resin content for MDF manufacture.

• International Commerce and Information Review
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• v.14 no.3
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• pp.307-322
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• 2012

The purpose of this paper is to examine determinants of export to the East Asia region, using panel unit root, panel cointegration framework, panel VECM (vector error correction model), panel FMOLS (fully modified OLS). Different panel unit root tests confirm that the data series are integrated processes with unit roots. When applying cointegration tests to long-run effect for aggregate panel data, a primary concern is to construct the estimators in a way that does not constrain the transitional dynamics to be similar among different countries of the panel. The regression equations are estimated by various panel cointegration estimators. The panel data causality results reveal that exchange rates has unidirectional effects on export and GDP, and there exists bidirectional causality between export and GDP. Also, the results from the panel FMOLS tests overwhelmingly reject the null hypothesis of zero coefficient. The panel cointegrating vectors show that the export has positive relationship with the GDP and ODI (overseas direct investment).

• Journal of the Korean Wood Science and Technology
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• v.29 no.3
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• pp.36-46
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• 2001

This study was to find a way of reusing wood and plastic wastes, which considered as a troublesome problem to be solved in this age of mass production and consumption, in manufacturing wood fiber-polypropylene fiber composite panel. And the feasibility of this composite panel as a substitute for existing headliner base panel of automobile was also discussed, especially based on physical and mechanical performance. Nonwoven web composite panels were made from wood fiber and polypropylene fiber formulations of 50 : 50, 60 : 40, and 70 : 30, based on oven-dry weight, with densities of 0.4, 0.5, 0.6, and 0.7 g/$cm^3$. At the same density levels, control fiberboards were also manufactured for performance comparison with the composite panels. Their physical and mechanical properties were tested according to ASTM D 1037-93. To elucidate thickness swelling mechanism of composite panel through the observation of morphological change of internal structures, the specimens before and after thickness swelling test by 24-hour immersion in water were used in scanning electron microscopy. Test results in this study showed that nonwoven web composite panel from wood fibers and polypropylene fibers had superior physical and mechanical properties to control fiberboard. In the physical properties of composite panel, dimensional stability improved as the content of polypropylene fiber increased, and the formulation of wood fiber and polypropylene fiber was considered to be a significant factor in the physical properties. Water absorption decreased but thickness swelling slightly increased with the increase of panel density. In the mechanical properties of composite panel, the bending modulus of rupture (MOR) and modulus of elasticity (MOE) appeared to improve with the increase of panel density under all the tested conditions of dry, heated, and wet. The formulation of wood fiber and polypropylene fiber was considered not to be a significant factor in the mechanical properties. All the bending MOR values under the dry, heated, and wet conditions met the requirements in the existing headliner base panel of resin felt.

• Journal of the Korean Recycled Construction Resources Institute
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• v.7 no.1
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• pp.57-65
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• 2019

In this study, the quality characteristics of the mother material of panel were evaluated for the production of moss panel using alumina cement and biological characteristics and environmental impact characteristics of moss panel were evaluated. The ratio of W/B 10%, Vs/Vm 20% and foaming agent 0.5% were selected as the basic mixing ratio for the mother panel of moss panel through pretest and SAP was added to improve the moisture content of panel. The optimal mixing ratio of SAP was considered to be less than 0.5% considering the quality characteristics. Also, through the use of alumina cement, the pH of the panel could be lowered to 10~11. The panel was able to improve the surface roughness through the foaming agent, and it was confirmed that the SAP had an effect of improving the moisture content of the panel. For the environmental impact characteristics of the moss panel, the moss panel evaluated the carbon dioxide reduction performance and the fine dust cleaning performance.

• Asian Journal for Public Opinion Research
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• v.11 no.3
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• pp.257-273
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• 2023

Conducting face-to-face surveys is difficult and cost prohibitive, necessitating a new attempt to build a probability-based panel in South Korea. Since 99.9% of adult Koreans own a mobile phone, mobile phone numbers provide a viable sampling frame. Random digit dialing (RDD) surveys were conducted August-December 2021. Of the 288,056 valid phone numbers dialed, 13,655 respondents between the ages of 19 and 69 completed a phone survey. These respondents were later invited by text message to join a panel; 3,202 of these (23.4% or 1.2% based on the number initially contacted) joined the panel. When compared to official government statistics like resident registration data, the census, or the Social Survey, this new probability-based panel can be said to be representative of the Korean population on the basis of age, gender, location, marital status, and household size after weighting is applied. However, even after weighting, panel members are more educated than the general population, white-collar workers and self-employed people are overrepresented, and blue-collar workers are underrepresented. As of February 2023, this panel has grown to 10,471 participants with plans to continue to invite more panel members in the same way. Based on the comparisons in this paper, we can regard this panel as a cost-effective, probability-based panel that may be used for various kinds of public opinion research, by researchers both within and outside of Korea. As we continue to refine and grow this panel, we hope it will become more widely used by researchers as well as provide a model for those building similar panels in other countries.

• Transactions of the Korean Society of Automotive Engineers
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• v.19 no.1
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• pp.139-146
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• 2011

In present study, it aims to compare the noise and vibration characteristics between magnesium alloy and steel hood panel. The AZ31 magnesium hood panel was fabricated through warm forming process, and the noise and vibration characteristics between both hood panels was compared through the measurement of engine radiation noise and transmission loss, as well as FRF on modal analysis. The sound insulation performance of magnesium alloy was wholly superior to that of steel hood panel, even though the transmission loss of magnesium alloy is lower than that of steel due to mass effect primarily. The FRF characteristics on modal analysis indicates that the resonance frequency of magnesium hood panel is remarkably increased to higher value than that of steel hood panel. The radiation and interior noise of magnesium panel even without acoustic hood insulation were remarkably lower than those of steel hood panel with acoustic insulation, in particular, at a range below 4,000 rpm.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.8 no.4
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• pp.497-509
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• 1996

Evacuated powder insulations have long been known to have better thermal performance than existing commercially available insulators, such as fiber glass and CFC-blown foam. To make a composite powder panel, a series of individually evacuated panels was encapsulated in a rigid closed cell foam matrix. The panels were encapsulated in a thin glass sheet barrier to preserve the vacuum. The thermal conductivity of the individual panel was found to be $0.0062W/m^{\circ}K$ by experiment and the polyurethane foam above had a thermal conductivity of $0.024W/m^{\circ}K$. In this study, numerical analysis using finite element method was carried out to investigate insulation performance of rigid foam/evacuated powder composite panel with respect to panel geometries such as panel pitch, panel aspect ratio and panel area ratio. Numerical analysis has indicated that more optimal vacuum panel geometries, much lower overall thermal conductivities can be achieved.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 1994.04a
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• pp.103-111
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• 1994

An interactive and iterative design method based on the constraint satisfaction problem (CSP) technique was developed to generate an ergonomically sound layout of a control panel. This control panel layout method attempts to incorporate a variety of relevant ergonomic principles and design constraints, and generate an optimal or, at least, a "satisfactory" solution through iterative interactions with the designer. The existing panel design and layout methods are mostly based on the optimization of single objective function formulated to reflect and trade off all ergonomic design objectives which are largely different in their nature. In fact, the problem of seeking an ergonomically sound panel design should be viewed as a multiple objective optimization problem. Furthermore, most of the design objectives should be understood as constraints rather than objectives to be optimized. Hence, a constraint satisfaction approach is proposed in this study as a framework for the panel designer to search through the design decision space effectively and make various design decisions iteratively. In order to apply the constraint satisfaction approach to the panel design procedure, the ergonomic principles such as frequency-of-use, importance, functional grouping, and sequence-of-use are formalized as CSP terms. With this formalization, a prototype system was implemented and applied to panel layout problems. The results clearly showed the effectiveness of the proposed approach since it permits designers to consider and iteratively evaluate various design constraints and ergonomic principles, and, therefore, aids the panel designer to come up with an ergonomically sound control panel layout.