• Journal of the Korean Crystal Growth and Crystal Technology
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• v.33 no.3
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• pp.116-123
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• 2023

A high intensity focuses ultrasound (HIFU) is one of the emerging technologies in the biomedical field. The piezoelectric HIFU transducer is a device that utilizes the thermal energy generated by high ultrasound energy. Recently an operating frequency of the HIFU transducer is to expand above a 7 MHz. In this study, the acoustic pressures and temperature distributions in the tissue that generated by the HIFU transducer at 10 MHz were calculated with the finite element method. In addition, the pressure focusing characteristics of the device were analyzed. The geometrical variables are the piezomaterial thickness, lens shape, water height, and film thickness. The results shown that the acoustic pressure increased and saturated gradually when the height/radius (H_L/R_L) ratio of the lens increased. Moreover, the focal area was gradually decreases with H_L/R_L ratio of the lens. In case of the optimized HIFU transducer, the maximum pressure and temperature were analyzed about 19 MPa and 65℃ respectively. And the -3 dB focused distances in the axial and lateral direction are around 2.3 mm and 0.23 mm respectively.

• The Journal of Engineering Geology
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• v.32 no.1
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• pp.41-57
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• 2022

A workflow is presented to estimate the size of a representative elementary volume and 3-D hydraulic conductivity tensor based on fluid flow analysis for a discrete fracture network (DFN). A case study is considered for a Cretaceous granitic rock mass at Gijang in Busan, Korea. The intensity and size of joints were calibrated using the first invariant of the fracture tensor for the 2-D DFN of the study area. Effective hydraulic apertures were obtained by analyzing the results of field packer tests. The representative elementary volume of the 2-D DFN was determined to be 20 m square by investigating the variations in the directional hydraulic conductivity for blocks of different sizes. The directional hydraulic conductivities calculated from the 2-D DFN exhibited strong anisotropy related to the hydraulic behavior of the study area. The 3-D hydraulic conductivity tensor for the fractured rock mass of the study area was estimated from the directional block conductivities of the 2-D DFN blocks generated for various directions in 3-D. The orientations of the principal components of the 3-D hydraulic conductivity tensor were found to be identical to those of delineated joint sets in the study area.

• Korean small business review
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• v.41 no.3
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• pp.49-75
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• 2019

Market instability offers opportunities as well as the need for careful innovation strategies and learning for a company's survival. Companies that find new opportunities decide to carry out innovation and decide on the size of their investments by considering their position in the market they are aiming for and the intensity of competition. This study was conducted to check whether obstacles to innovation face by SMEs in the manufacturing sector vary depending on the stage of corporate growth and to identify the impact of the government support system on the decision-making process on the performance of innovation. According to the analysis, there were differences in obstacles to innovation depending on the stage of corporate growth. It was found that more innovative SMEs are, more obstacles they face, and to overcome such obstacles, they try to access government support systems more. In addition, the use of a government support system eliminated obstacles to innovation, and the positive and significant effects of investing in innovation were identified. This study is meaningful in that it explicitly approached these hypotheses by applying a multistage model to the process of innovation carried out by SMEs in the manufacturing sector.

• Korean small business review
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• v.41 no.2
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• pp.25-50
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• 2019

Although Korean government has implemented size-dependent policy, so called "the designation of SMEs-suitable industry", promoting SMEs growth, our understanding in the effectiveness of the policy is limited. We investigate the effect of the policy on SMEs performance in food product and beverages industry, which accounts for the majority in the SMEs-suitable industry. From the perspective of sales, profitability, and R&D intensity, which is regarded as indigenous effort for growth, we find the heterogeneity in the effectiveness of the policy across the sub-sectors in the industry. However, overall the policy does not significantly contribute to the growth of sales, profitability, and facilitation of R&D activity for indigenous innovative efforts of SMEs. Our study advances the theoretical discussion on the effect of the policy with the disaggregated level of analysis, i.e, sub-sector level. Our findings also contribute to the resolution of social and political conflicts between pros and cons of the policy. Our study suggests that policy makers should develop more sophisticated policy that incorporate the specific characteristics of individual sub-sectors. They also need to invest more resources in enhancing the effectiveness of the policy and accelerating SMEs innovative efforts.

• Knowledge Management Research
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• v.24 no.2
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• pp.65-85
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• 2023

This paper investigates how TMT's cognitive traits affect R&D investment. Drawing on the attention-based view, we propose that TMT's future orientation and risk preference increase the level of R&D investment. As R&D activities have long-term goal of generating proprietary knowledge, it is important to understand how TMT's attention toward future and risk affect R&D investment. Also, we test the moderating effect of CEO duality on R&D investment. As the CEO plays a leadership role in the TMT, if the CEO's decision-making authority is highly concentrated, the impact of TMT on R&D may decrease. We measure CEO duality and CEO ownership stake as CEO characteristics. Based on a sample of 837 U.S. manufacturing firms, the results show that when TMT has a higher tolerance for risk and higher future orientation, R&D intensity increases. However, when CEO also serves as chairman of board and CEO has higher ownership, TMT's influence on R&D investment weakens. This implies that TMT and CEO has power dynamic that can change based on CEO power supporting status. Overall, it suggests that TMT's attention and CEO power are important factors to improve longer-term knowledge accumulation of firm.

• Earthquakes and Structures
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• v.24 no.6
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• pp.455-475
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• 2023

The present study investigates the non-linear soil-pile interaction using three-dimensional (3D) non-linear finite element models. The numerical models were validated by using the results of extensive pile load and shaking table tests. The pile performance in liquefiable and non-liquefiable soil has been studied by analyzing the liquefaction ratio, pile lateral displacement (LD), pile bending moment (BM), and frictional resistance (FR) results. The pile models have been developed for the different ground conditions. The study reveals that the results obtained during the pile load test and shaking cycles have good agreement with the predicted pile and soil response. The soil density, peak ground acceleration (PGA), slenderness ratio (L/D), and soil condition (i.e., dry and saturated) are considered during modeling. Four ground motions are used for the non-linear time history analyses. Consequently, design charts are proposed depended on the analysis results to be used for design practice. Eleven models have been used to validate the capability of these charts to capture the soil-pile response under different seismic intensities. The results of the present study demonstrate that L/D ratio slightly affects the lateral displacement when compared with other parameters. Also, it has been observed that the increasing in PGA and decreasing L/D decreases the excess pore water pressure ratio; i.e., increasing PGA from 0.1 g to 0.82 g of loose sand model, decrease the liquefaction ratio by about 50%, and increasing L/D from 15 to 75 of the similar models (under Kobe earthquake), increase this ratio by about 30%. This study reveals that the lateral displacement increases nonlinearly under both dry and saturated conditions as the PGA increases. Similarly, it is observed that the BM increases under both dry and saturated states as the L/D ratio increases. Regarding the acceleration histories, the pile BM was reduced by reducing the acceleration intensity. Hence, the pile BM decreased to about 31% when the applied ground motion switched from Kobe (PGA=0.82 g) to Ali Algharbi (PGA=0.10 g). This study reveals that the soil conditions affect the relationship pattern between the FR and the PGA. Also, this research could be helpful in understanding the threat of earthquakes in different ground characteristics.

• Journal of Korean Tunnelling and Underground Space Association
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• v.25 no.4
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• pp.331-344
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• 2023

The performance of the existing tunnel scanning system was analyzed through the post-evaluation of NETIS (New Technology Information System) and Inspection Support Technology Performance Catalog. Suggestions for improvement and development direction of the tunnel scanning system were deduced. As new technology of Japan gave priority to providing user-centered information, it was possible to objectively compare and analyze the characteristics of various tunnel scan systems through post-evaluation of NETIS and standard test methods in the Inspection Support Technology Performance Catalog. Construction New Technology of Korea was centered on suppliers of technology certification, making it impossible to objectively compare the performance of tunnel scanning systems. The performance was compared and evaluated indirectly by comparing the specifications of the camera, which is a core device of Japan's tunnel scanning system. For the future development of tunnel scanning systems, high-resolution and fast exposure performance of cameras and corresponding high-intensity lighting devices are required. For this purpose, it is necessary to make an experimental environment in which the performance of the camera and lighting can be analyzed indoors.

• Analytical Science and Technology
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• v.20 no.5
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• pp.361-369
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• 2007

Uncomfortable odor emitted from air conditioning system is the main cause of indoor air quality deterioration. To solve evaporator odor problems, odor active compounds, have to be identified then the quality of the product can be improved its quality. Because evaporator odor in exhaust gas has low odor intensity and discontinuity, it is very difficult to collect and analyze sample. In this study through the identification of odor compounds in condensed water, the evaluation of the eraporator was tested. Odor compounds were extracted from water by headspace-solid-phase microextraction (HS-SPME) method. The single odor was separated by GC/FID/Olfactometry (GC/FID/O) and odor active compounds were identified by GC/AED and GC/MS. Compared to air sample, result of sensory evaluation and the single odor compound appeared similarly. It was identified that odor active compounds have functional group containing oxygen such as alcohols and acids. Evaluation method of odor active compounds using condensed water in evaporator appeared effective on the side of simplicity of collection, low expanse and rapid analysis.

• Exercise Science
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• v.21 no.1
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• pp.111-120
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• 2012

The purpose of the study was to assess the effects of different cardiorespiratory fitness response to exercise training on cardiovascular disease and adipocytokine release and gene expression in abdominal obesity women. forty eight middle-age women were divided to a exercise-responder (n=34) group (ERG) and a exercise-nonresponder (n=14) group (ENRG) based on cardiorespiratory fitness after exercise training (12weeks, 1200 kcal/week, moderate-vigorous intensity, walking and jogging). Cardiorespiratory fitness was measured using maximal oxygen uptake with metabolic gas analysis and body composition was determined by bioelectrical impedance. We measured lipid and glucose profiles, blood adipocytokines and adipocytokine genes expression in adipose tissue. Waist girth (p=0.040), and %body fat (p=0.031) were significantly decreased in ERG than ENRG. Triglyceride (p=0.023) and systolic blood pressure (0.046) were significantly decreased in ERG than ENRG. Blood leptin (p=0.022) was significantly decrease in ERG than ENRG but leptin gene expression was decreased both groups (p<0.001). These results show that exercise-responder group improved cardiovascular disease risk factors and adipocytokine more than exercise-nonresponder group after exercise training. Moreover, exercise-nonresponders group show that obese indices and blood leptin and leptin gene expression in adipose tissue were decreased despite the failure to improve fitness. Therefore, regular exercise training seems to give health benefits although the failure to improve fitness.

• 한국노년학
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• v.29 no.3
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• pp.1159-1182
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• 2009

The purpose of this study is to examine everyday emotional experience of urban elderly in Korea. Specifically, this study explores gender differences in the effect of place/location of activity and companionship on the daily emotional experience. Data were collected from 148 urban elderly (men=76, women=72) in Seoul, using Experience Sampling Method(ESM). The unit of analysis was the self-report and in total 5,530 self-reports were provided. The statistical methods used for the data analyses were descriptive statistics, t-test, χ² verification, and ANOVA. The major findings are as follows. First, the elderly in Korea spend a quite substantial portion of their time at home, and they spend the largest share of their time in company with their spouse. Second, women report higher intensity of stress and irritation than men in terms of overall emotional experience. Third, the effect of activity location and companionship on emotional experience turned out to be different depending on gender. Emotional experience of daily lives and overall quality of life are shown to be inter-related. Based on these findings, this study provides a significant implication that situational contexts of experience should be considered in order to understand the daily emotional experience of the contemporary Korean elderly.