• Transactions of the Korean Society of Mechanical Engineers A
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• v.36 no.10
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• pp.1195-1203
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• 2012

Welding is a well-developed, widely used process for permanently joining metal components. However, the mechanical reliability of welded parts still offers room for improvement. A weld region consists of a fusion zone, a partially melted zone, and a heat-affected zone, and each zone has different material properties. In addition, the geometrical shape of a weld bead or fillet influences the mechanical reliability. A precise structural analysis must consider how a local welded region influences the mechanical behavior of the entire structure. This study focuses on an effective modeling scheme for the weld region. It relies on experimental and numerical methods to determine the proper correlation based on experimental results and to propose a modeling scheme for welded parts.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.35 no.7
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• pp.805-812
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• 2011

In this study, a cantilevered energy harvester comprising piezoelectric fiber and epoxy composites was designed and analyzed electro-mechanically. In order to maximize the power of the cantilevered energy harvester, its exciting frequency was tuned to the first natural frequency of the beam. An efficient analysis method for predicting the output voltage of the beam was developed by using the finite element method coupled with piezoelectric behavior. By using this method, the effects of geometric parameters and various piezoelectric materials on power generation were investigated and the electric characteristics were evaluated. Design optimization of the beam geometries was performed for a base model. The optimum MFC design generated a maximum electric output of 40.1 V at a first natural frequency of 24.5 Hz.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.37 no.11
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• pp.1355-1360
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• 2013

A cracked solid propellant would have failure or fracture of rocket because of excessive combustion according to increase of burning area, therefore it is important to evaluate the fracture toughness of solid propellant. A procedure is used to investigate the material under a range of test temperatures between -60 and $60^{\circ}C$, three kind of specimen thickness, 4, 12.5 and 24.5 mm to determine the effect of two parameters on the fracture toughness. A center cracked tension (CCT) specimen is used in these tests, which were conducted using INSTRON 5567 testing machine and environmental chamber to evaluate the fracture toughness. The experimental results show that the fracture toughness tends to decreases with an increase in the temperature, and the effect of thickness indicates that the fracture toughness is highest at 12.5 mm under various temperatures except $-60^{\circ}C$. It is found that the fracture toughness of solid propellant is changed due to glass transition behavior around $-60^{\circ}C$.

• Applied Chemistry for Engineering
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• v.5 no.2
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• pp.189-198
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• 1994

The adsorptive behaviors of carbon monoxide and methanol over $V_2O_5$catalyst were studied by means of thermal desorptlon spectroscopy (TDS) under ultrahigh vacuum conditions. Carbon monoxide adsorbed on oxygen-deficient V sites as well as on V=O groups of the $V_2O_5$ surface. CO adsorbed on the V sites desorbed at 380 K while CO adsorbed on the V=O groups formed carbonate species with surface oxygen of $V_2O_5$ and desorbed as $CO_2$ resulting in the reduction of the surface of she $V_2O_5$catalyst. The amount of CO adsorbed in the form of carbonate species increased by both the pre- and post-adsorbed oxygen. The adsorptive behavior of methanol over the catalyst was studied by thermal desorption experiments of $CH_3OH$, HCHO, CO, and $H_2$ upon methanol adsorption at 298 K. The results showed that methanol was adsorbed dissociatively on the $V_2O_5$catalyst as methoxy and hydroxyl groups at 298K.

• Korean Journal of Human Ecology
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• v.17 no.5
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• pp.989-999
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• 2008

The purpose of this study was to supply the basic data for the plan of the storage space in the kitchen by investigating the actual condition of the use and residents' satisfaction. The questionnaires were distributed to 136 families of the local apartment in South Chung-Cheong Province of Korea. The results were summarized as follows; first, among the furniture for storage, the upper and lower space have been installed in every furniture. The general tablewares were stored in the upper part of the kitchen and the frequently used goods for cooking were largely stored in the lower part. Second, in the method of reforming the kitchen space, it showed highest figure in case of purchasing the shelf and there were many cases of storing things by using the subsidiary storage furniture and boxes and it came to the conclusion that the housewives have a tendency to solve the storage problem by using the less expensive, simple and passive ways. Third, in the degree of satisfaction for the space for storage, it showed that the respondents were a little bit dissatisfied with the size of storage space, the position of furniture for storage, the convenience for using and the storage rapacity. Among the furniture for storage in the kitchen, the degree of satisfaction for the upper and lower parts was a little bit low, but it is higher for the others. For the plan of storage space, the aesthetic appreciation reflects visually being in order was considered to be the important factor.

• Transactions of the Korean hydrogen and new energy society
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• v.25 no.1
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• pp.59-71
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• 2014

An experimental study has been conducted to investigate the heat transfer characteristics of laminar syngas/air mixture with 10% hydrogen content impinging normally to a flat plate of cylinder. Effects of impinging distance, Reynolds number and equivalence ratio as major parameters on heat fluxes of stagnation point and radial direction were examined experimentally by the direct photos and data acquisitions from heat flux sensor. In this work, we could find the incurved flame behavior of line shaped inner top-flame in very closed distance between flat plate and burner exit, which has been not reported from general gas-fuels. There were 3 times of maximum and 2 times minimum heat flux of stagnation point with respect to the impinging distance for the investigation of Reynolds number and equivalence ratio effect. It was confirmed that the maximum heat flux of stagnation point in 1'st and 2'nd peaks increased with the increase of the Reynolds number due to the Nusselt number increment. There was a third maximum rise in the heat flux of stagnation point for larger separation distances and this phenomenon was different each for laminar and turbulent condition. The heat transfer characteristics between the stagnation and wall jet region in radial heat flux profiles was investigated by the averaged heat flux value. It has been observed that the values of averaged heat flux traced well with the characteristics of major parameters and the decreasing of averaged heat flux was coincided with the decreasing trend of adiabatic temperature in spite of the same flow condition, especially for impinging distance and equivalence ratio effects.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.39 no.11
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• pp.1113-1121
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• 2015

In this study, we have focused on the design of a controller and an operating program for the operation of the hydraulic actuators used in a shaker. To control the motion of the shaker accurately, the position of each hydraulic cylinder should be controlled precisely even under an uncertain environment. For this purpose, we have suggested a control algorithm using an FRF (frequency response function) based control which senses the behavior of the actuator in advance, calculates a transfer function through the system identification method, and provides the final control input. The experimental results on the performance of this system were compared with that of a simple PID control algorithm.

• Korean Journal of Environment and Ecology
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• v.9 no.2
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• pp.187-196
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• 1996

Visitors to O-Daesan National Park were surveyed from July 28 to 31 in 1995. During that time, 392 visitors were contacted. Of those individuals, 52% were males and 48% of females. 68% of respondents reported that they had gone as far as college. 50% were 20 years of age. the largest percentage of respondents were reported that they visited O-daesan Nat'l Park for enjoying natural landscape. In group type, 40% were traveling with their family and 36% with their friends. In activity characteristics, 38% were 1 day-2nights visitors and 37% were day-time visitors. 45% did cooking and 21% were mentioned carrying in their own food. Generally most respondents were perceived that the environmental pollution. Most respondents were not likely to intervene to stop other visitors' depreciative behavior(Bystander intervention behavior). And their perceived broadcasting for guidance of use in National Park.

• Journal of the Korean Society of Costume
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• v.56 no.1 s.100
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• pp.56-69
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• 2006

The purposes of this study were to identify cosmetics purchasing behavior according the 20-30 year old men's lifestyle. The results were as follows; 1. The factors of men's lifestyle were sense of fashion, participation of social activities, use of web-based information, sense of androgyny, economical efficiency, provision of web-base information, sport activities, and pursuit of change, and they were segmented into a passive stagnant group, a economic web-base information utilizing group, a positive social activity participation group, and a sensitive appearance change pursuit group. 2. Passive stagnant group used less information sources patronized cosmetics specialty store, did not select their cosmetics by themselves, and spent less for their cosmetics. Economic web-base information utilizing group used information sources positively, patronized cosmetics discount store or internet shopping, and spent less for cosmetics. Positive social activity participation group patronized cosmetics specialty store or discount store, but did not select cosmetics by themselves. Sensitive appearance change pursuit group patronized department store or internet shopping for cosmetics, selected cosmetics by themselves, and spent more. 3. Passive stagnant group showed a tendency of older, less educated, and lower incomes, but economic web-base information utilizing group were among the age of 20's, lower educated, and the unmarried with average incomes. Positive social activity participation group showed a tendency of older, highly educated, and the married with jobs, but sensitive appearance change pursuit group were among the age of 20's and university students with more incomes and pocket money.

• KIISE Transactions on Computing Practices
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• v.23 no.10
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• pp.599-604
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• 2017

A useful application of smart assistants is to predict and suggest users' daily behaviors the way real assistants do. Conventional methods to predict behavior have mainly used explicit schedule information logged by a user or extracted from e-mail or SNS data. However, gathering explicit information for smart assistants has limitations, and much of a user's routine behavior is not logged in the first place. In this paper, we suggest a novel approach that combines explicit schedule information with patterns of routine behavior. We propose using inference based on a Markov decision process and learning with a reward function based on inverse reinforcement learning. The results of our experiment shows that the proposed method outperforms comparable models on a life-log dataset collected over six weeks.