• The Journal of the Korea Contents Association
• /
• v.15 no.2
• /
• pp.393-407
• /
• 2015

This study is intended to look into the effects of small business startup environments on failure burden and startup failure. To achieve this, a survey was carried out to 300 small business CEOs in Seoul. The results were as follows. First, the effect of startup environments on failure burden showed that management environment, business environment, internal organizational environment and external organizational environment had a negative effect on failure burden. Second, the effect of startup environments on financial and non-financial losses showed that startup management environment, startup business environment and internal organizational environment had a negative effect on financial and non-financial losses. Third, the effect of failure burden on startup failure showed that failure burden had a positive effect on financial and non-financial losses. Consequently, this study indicates that internal organizational commitment and communication are important attributes affecting failure burden, financial and non-financial losses, compared with management quality, entrepreneurship and business environment.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
• /
• v.15 no.1
• /
• pp.51-58
• /
• 2001

Recently, DC-DC converters significantly increase the total losses as rising switching frequency. Trnditional soft switching technique for reducing switching losses even increase voltage/Clment stress of switch In this paper, Resonant circuit for soft switching is connected in parallel with power stage and only operates just before tum-on of the main sWItch. Therefore, ills doesn't affect the total circuit QI'||'&'||'pound;ration. The object of tIns paper is to make the linearized equivalent loss mxleIs. and to analyze the total losses by experiment. ZVT-PWlvI converter designed with 170-260[V] input, 400[V] 5[A] output, and 100[kHz] switching frequency is tested respectively with 500[W], 1[kW], 1.5[kW], and 2[kW] loads. The total losses in input 220[V], 2[kW] load are analyzed by usirm the linearized equivalent loss models.

• The Transactions of the Korean Institute of Electrical Engineers P
• /
• v.59 no.4
• /
• pp.358-363
• /
• 2010

This paper proposes a step-by-step method of determining the parameters of equivalent circuit which is considered the no load losses for the single phase induction motor which has the starting winding. This method is comprised of three steps, and the stator resistance which is measured by the method of voltage drop is treated as constant and the stator and the rotor leakage reactances are assumed to be the same in every step. The test results of no load and locked rotor test are used in the 1st and 2nd step, and the ratings of name plate of the motor are needed in the 3rd step. In the 1st step, the traditional equivalent circuit parameters are directly calculated by no load and locked rotor conditions. In the next step, five nonlinear simultaneous equations for five unknown parameters can be set up by no load and locked rotor equivalent circuits. These equations are solved by using the initial parameters obtained by the 1st step parameters. In the final step, three nonlinear simultaneous equations for rotor winding resistance, leakage reactance and no load losses component resistance can be set up by equivalent circuit under the rated operation. Three parameters are solved by using the 2nd step parameters. Thus, equivalent circuit parameters are gradually refined step by step. The validity of the proposed method is evaluated by comparing the computed values obtained by the equivalent circuit parameters with the experimental values of the load test.

• Journal of the Korea Institute of Information Security & Cryptology
• /
• v.12 no.3
• /
• pp.39-47
• /
• 2002

This paper deals with study of a new framework for the traceback of distributed DoS(Denial of Service) attacks in the Internet, in which many sources flood "spoofed" IP packets towards a single victim. In our scheme, the destination host traces those anonymous packets' losses, and infers the logical end-to-end paths back towards the sources. This method is based on the fact that there is a strong correlation between packet losses when those packets traverse along a same route, and the simulation results show high probabilities of detecting the topology under a certain condition. Compared with previous approaches, our scheme has a number of distinct features: It can be performed in realtime or non-realtime, without any supports of routers or ISPs. Our results may be applied to the inference of physical topology and to support previous approaches.pproaches.

• The Journal of the Korea Contents Association
• /
• v.21 no.11
• /
• pp.692-710
• /
• 2021

This study aimed to validate the Awareness of Age-Related Change (AARC) scale developed by Brothers et al. (2019) for the Korean elderly. This study took the elderly people in Seoul (over 65 years old) as participants to examine the aging perception of the elderly themselves. For this purpose, we conducted exploratory and confirmatory factor analyses (EFA, CFA) with two samples (sample 1: N = 185; sample 2: N = 215). EFA revealed and CFA confirmed a two-factor structure consisting of awareness of gains and awareness of losses. Specifically, the awareness of losses had two subfactors consisting of awareness of losses in health and awareness of losses in non-health, while the awareness of gains had no subfactor. Finally, we examined the relationship between AARC, attitudes toward own aging, and emotions then discussed the implication, limitations of this study, and future direction.

• Journal of The Korean Society of Agricultural Engineers
• /
• v.64 no.3
• /
• pp.53-61
• /
• 2022

This study evaluated the impacts of subsurface drainage design, i.e., spacing and depth, on agricultural productivity and environmental sustainability in two tile-drained fields (Sites A and E) under a corn-soybean rotation in the Midwestern United States. A calibrated and validated Root Zone Water Quality Model (RZWQM) was used to simulate Nitrate-N (nitrogen) losses to tile drainage and crop yields of 30 tile spacing and depth scenarios over 24 years (1992-2015). Our results presented that the narrower and deeper the tile drains are placed, the greater corn yield and Nitrate-N losses, indicating that the subsurface drainage design may cause a trade-off between agricultural productivity and environmental sustainability. The simulation results also presented that up to about 255.7% and 628.0% increase in Nitrate-N losses in Sites A and E, respectively, far outweigh the rate of increase in corn yield up to about 1.1% and 1.6% from the adjustment of tile spacing and depth. Meanwhile, the crop yield and Nitrate-N losses according to the tile configuration differed depending on the field, and the soybean yield presented inconsistent simulation results, unlike the corn yield, which together demonstrate the heterogeneous characteristic of agro-environmental systems to a subsurface drainage practice. This study demonstrates the applicability of agricultural systems models in exploring agro-environmental responses to subsurface drainage practices, which can help guide the introduction and installation of tile systems into farmlands, e.g., orchards and paddy fields, in our country.

• Journal of Family Resource Management and Policy Review
• /
• v.8 no.1
• /
• pp.1-13
• /
• 2004

This study examined in detail the Japanese system of redressing consumers' losses and the overall consumer administrative system and compared them with the Korean counterpart to seek for a direction of reforming the systems. Several policy suggestions could be made as follows to activate the systems and improve the performances of the consumer administration in both Japan and Korea. First, in Japan, consumer center must be efficiently operated while private consumer groups, firms, consumer agencies and other organizations must actively join to actively redress consumers' losses and implement other consumer policies. Second, in Korea, regional consumer policies are weak so that they must learn Japanese well-developed regional consumer administration system by examining their current development, strengths, and weaknesses. Third, working conditions must be urgently improved, increasing the number of consumer counselors who are involved in consumer policies as well as to guarantee minimum level of their payment. On the other hand, the trend of hiring married and old employees being responsible for implementing consumer policies in Japan must be improved. Fourth, divisions of works in consumer policies among consumer groups as well as their specialization in Korea are necessary. Finally, as counseling of consumers through internet were not available in Japan, that type of counseling must introduce and become more popular in the future.

• The Transactions of the Korean Institute of Power Electronics
• /
• v.18 no.3
• /
• pp.247-255
• /
• 2013

In this paper, a soft switching DC-DC converter for AC module type photovoltaic (PV) module integrated converter is proposed. A push-pull converter is suitable for a low voltage PV AC module system because the step-up ratio of a high frequency transformer is high and the number of primary side switches is relatively small. However, the conventional push-pull converters do not have high efficiency because of high switching losses by hard switching and transformer losses (copper and iron losses) by high turns-ratio of the transformer. In the proposed converter, primary side switches are turned on at zero voltage switching (ZCS) condition and turned off at zero current switching (ZVS) condition through parallel resonance between secondary leakage inductance of the transformer and a resonant capacitor. Therefore the proposed push-pull converter decreases the switching loss using soft switching of the primary switches. Also, the turns-ratio of the transformer can be reduced by half using a voltage-doubler of secondary side. The theoretical analysis of the proposed converter is verified by simulation and experimental results.

• Steel and Composite Structures
• /
• v.19 no.1
• /
• pp.43-58
• /
• 2015

There are many studies on the optimization of steel trusses in literature; and, a large number of them include a shape optimization. However, only a few of these studies are focused on the prestressed steel trusses. Therefore, this paper aims to determine the amounts of the material and cost savings in steel plane trusses in the case of prestressing. A parallel-chord simply supported steel truss is handled as an example to evaluate the used approach. It is considered that prestressing tendon is settled under the bottom bar, between two end supports, using deviators. Cross-sections of the truss members and height of the truss are taken as the design variables. The prestress losses are calculated in two steps as instantaneous losses and time-dependent losses. Tension increment in prestressing tendon due to the external loads is also considered. A computer program based on genetic algorithm is developed to solve the optimization problem. The handled truss is optimized for different span lengths and different tendon eccentricities using the coded program. The effects of span length and eccentricity of tendon on prestressed truss optimization are investigated. The results of different solutions are compared with each other and those of the non-prestressed solution. It is concluded that the amounts of the material and the cost of a steel plane truss can be reduced up to 19.9% and 14.6%, respectively, by applying prestressing.

• Journal of Electrical Engineering and Technology
• /
• v.12 no.1
• /
• pp.225-229
• /
• 2017

This paper describes the loss analysis based on load conditions of the air conditioning compressor motors using variable dc-link voltage. The losses of PMSM (Permanent Magnet Synchronous Motor) should be analyzed by the PWM (Pulse Width Modulation) output of inverter. The harmonic loss by the PWM cannot consider that using the current source analysis of the inverter. In addition, when the voltage of dc-link is variable with the condition of variable speed and load conditions in motor, the losses of motor are also changeable, however it is hard to analyze those losses by only electromagnetic finite element method (FEM). Therefore, this paper proposes the analysis method considering the carrier frequency of the inverter and the varying state of the dc-link voltage through the FEM-control coupled analysis. Using proposed analysis method, additional core loss and eddy current loss of permanent magnet caused by PWM could be analyzed. Finally, the validity of the proposed analysis method is verified through the comparison the result of coupled analysis with experiment.