• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.15 no.6
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• pp.540-547
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• 2004

In this paper, a current - mode class D(CMCD) power amplifier over 70 % power added efficiency at 900 ㎒ is designed and implemented. Based on push-pull class B structure, main power loss due to charge and discharge of output capacitance in switching mode power amplifier is minimized by applying a parallel harmonic control circuit. Experimental CMCD amplifier with 73 % power added efficiency at 3.2 W and 72 % power added efficiency at 5 W are achieved respectively. In addition a characteristic of switching mode power amplifier whose output power is proportional to magnitude of U power is verified.

• Proceedings of the Korea Information Processing Society Conference
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• 2020.11a
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• pp.131-134
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• 2020

최근 '코로나 19 (COVID-19)'와 '최저임금 이슈' 등 다양한 외적 요인들이 아르바이트를 포함한 고용시장을 변화시키고 있다. 생계와 학자금을 위해 아르바이트에 뛰어드는 청년들에게는 악재의 연속이다. 이처럼 외부 환경은 점점 구직자에게 불리하게 작용하는데 반해, 이들을 사용자로 둔 구인구직 플랫폼은 수년 째 변화의 모습을 보이지 않는다. 기존 플랫폼은 구인자에게 지나치게 유리한 소통구조를 지니고 있으며, 최근 고용시장의 변화에 따른 단기 및 대타 고용의 수요를 충족시키지 못한다. 따라서 본 논문에서는 기존 구인구직 플랫폼의 문제점을 지적함과 동시에 플랫폼이 사용자의 편의를 충족시키기 위해 지녀야 할 고용의 역방향성과 데이터베이스 기반 필터링 및 추천과 같은 핵심 기능들에 대해 자세히 밝히고자 한다. 이를 통해, 사회적 트렌드인 긱 경제를 활성화시킬 뿐만 아니라 구직자 다수를 차지하는 청년들의 구직부담을 완화시킬 수 있을 것이라 기대한다.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.22 no.1
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• pp.461-467
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• 2021

Among the defect factors that can occur when a wafer-level lens is molded using a thermosetting material, the mold sticking problem of a molded lens during the release process can damage the molded substrate and deform the substrate at the wafer level. An experiment was conducted to examine the factors affecting the demolding force in the lens forming process. The demolding force was examined according to the coating material of the molds. The mold was surface-treated with ITO and Ti, followed by plasma treatment in an O2 atmosphere. A DLC coating was then performed, and the curing and releasability were examined. A coating method for the pull-off experiment was selected based on the results. To measure the demolding force according to the curing process conditions, a method of curing at a constant pressure and a method of curing at a constant position were applied. As a result, the TiO2 surface treatment reduced the release force. When cured by controlling the location, curing shrinkage can reduce the adhesion energy of the interface during curing, resulting in better demolding.

• Journal of Venture Innovation
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• v.7 no.1
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• pp.201-223
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• 2024

This study undertook an empirical analysis to examine the impact of various factors on entrepreneurial intention among young people, with a particular focus on the role of startup mentoring. Employing a survey distributed nationwide, data from 250 valid respondents were subjected to structural equation modeling to investigate these dynamics. The analysis uncovered that workplace stress, subjective norms, and perceived behavioral control positively influence the entrepreneurial intentions of youth. Meanwhile, technological constraints negatively affected these intentions. The study did not explore the potential effects of future uncertainty and the burden of failure. Significantly, it was found that startup mentoring plays a crucial role in mitigating the negative impacts that may deter young individuals from pursuing entrepreneurship. Mentoring was instrumental in reducing negative influences, thereby fostering a more conducive environment for entrepreneurial ambition. By integrating the Push-Pull-Mooring (PPM) and Theory of Planned Behavior (TPB) models, this research not only validates these frameworks within the context of youth entrepreneurship but also underscores the essential function of startup mentoring in enhancing entrepreneurial intentions. The insights from this study highlight the importance of mentoring programs in nurturing the entrepreneurial spirit among the youth, suggesting that targeted mentoring support can play a pivotal role in overcoming barriers to entrepreneurship.

• Archives of design research
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• v.18 no.2 s.60
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• pp.155-164
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• 2005

Home-service robots need to have sufficient spatial information about the surroundings for interacting with human intelligently and performing services efficiently. It is very important to investigate the efficient interaction style that supports map building task through human-robot collaboration. We first analyzed map building task with a cleaning robot and drew 4 design factors and tentative solutions, including map building procedure (task-preferred procedure/space- preferred procedure), LCD display installation (robot/robot+remote control), navigation method (push type/pull type), feedback modality(GUI/GUI+TTS). The design factors and tentative solutions were defined as independent variables and levels. This research investigated how those variables affect to the human task performance and behavior in map building tast. 8 kinds of experiment prototypes were built and usability test among 16 house wives was conducted for acquiring empirical data. As the experiment result, in terms of map building procedure, space-preferred procedure indicated better task performance than task-proffered procedure as we expected. For the LCD display installation factor, remote control with LCD display indicated higher task performance and subjective satisfaction. In robot navigation method, it was very difficult to find a significant difference between push type and pull type which contrary to our expectation. In fact, push type indicated higher subjective satisfaction. Also in feedback modality, we have acquired negative feedback an additional TTS operation guidance. It seems that robot's autonomy before achieving spatial information is rudiment condition which means users are just interacting with a mobile appliance. Thus they prefer remote-control-based interaction style in robot map building process as they used in traditional appliance control.

• Journal of the Economic Geographical Society of Korea
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• v.7 no.2
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• pp.203-225
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• 2004

The purpose of this paper analyzes the characteristics of economic space in Gyeonggi border regions. Especially, this study focuses on understanding the environment enveloped the enterprises because today, largely influenced factor for regional economic development is enterprises. Since 1990's the change of the spacial organization in Korean Capital region has been inducing the functional transformation in Gyeonggi border regions so that new function -beyond military functions- is developed in these regions. By the disindustrialization in core region contributed to the industrialization in periphery, border regions are developed as a concentrated space of traditional industries and small size manufactural firms. The most important pull factor is facility for obtain a factory site and favorable condition of land price. Globally, the reasons to locate enterprise in these regions are found not in positive and progressive strategies but in passive and defensive strategies. Therefore few enterprise carried about influences of economic cooperation between North and South Korea at the moment of decision of their site. The survey reveal that enterprises didn't highly estimate the environment in border regions as their business activities. The first dissatisfied condition is insufficiency of labour and difficulty of access for administrative and high level services, due to geographical separation. Considering the recent tendency of spacial reorganization in Capital region is not always good for border regions, border regions have to employ a policy with the object of ameliorating regional business environments and growing up a potentiality of endogenous development.

• Korean Journal of Applied Biomechanics
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• v.30 no.1
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• pp.7-16
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• 2020

Objective: It is to find factors related to stability through analysis of plantar pressure factors according to the level of instability when performing Snatch. Method: Foot pressure analysis was performed while 10 weightlifters performed 80% of the highest level of Snatch, and motion was classified and analyzed in 3 grades according to the level of instability. Results: First, in Bad Motion, the movement distance of the pressure center in the direction of ML and AP was larger significantly in Phase 2. Second, in Phase 2, the number of zero-crossing in the AP direction was larger statistically significantly in Good Motion. Third, in the bad motion in Phase 3, the number of zero-crossing in the ML direction showed a significantly larger value. Fourth, in Phase 4, it was found that the more stable the lock out motion, the greater the activity of foot controlling in the left and right directions. Fifth, Phase 3, the greater the Maximum/Mean foot pressure value, the more stable the pulling action. Sixth, in Phase 2, the foot pressure was concentrated with a wide distribution in the midfoot and rearfoot. Seventh, the triggering number of the forefoot region was small in the last pull phase. Eighth, the number of triggers in the toe area was significantly higher during Good Motion in Phase 4. Conclusion: Summarizing the factors of instability in Snatch, there was no significant difference in Phase 1 for each condition. In order to enhance the stability in Phase 2, the sensory control ability in the AP direction is required, and focusing the foot pressing motion with a wide distribution in the middle and rear parts increases the instability. In Phase 3, it was found that the more unstable, the more sensory control activity was performed in the ML direction, the stronger the forefoot pressing action should be performed for a stable Snatch. In Phase 4, It is important that the feet sensory control activity in ML directions and the control ability of the toes in order to have stable Lock out motion.

• Journal of Korean Society of Rural Planning
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• v.26 no.2
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• pp.39-49
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• 2020

This study was attempted to grasp the push-pull factors of urban to rural migrants in relation to services and infrastructure of rural welfare and culture. Online and offline survey were conducted for urban residents who were willing to return to the rural area and those who were already returning to the rural area. In the fields of health care, social welfare, and education, it was found that the satisfaction level of urban-to-rural migrants was relatively higher than those of latent urban-to-rural migrants. In the field of culture, leisure and sports, the level of satisfaction and concern were similar, so it was found that the expectations for the field were relatively high before returning rural area. As for the agreement degree to expand support, the demand for emergency medical facilities and dementia care program was the highest, and the demand for health care was found to be relatively high. The results of the survey on the top priority items indicate that latent urban-to-rural migrants require support of facility and space item and expansion of program item, and urban-to-rural migrants have high demand for expansion of program item in all field except healthcare field. The results of this study are expected to provide useful information for establishing the direction of the rural area development project in connection with the revitalization of policy of people return to rural area.

• Journal of the Korean Society of Safety
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• v.37 no.1
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• pp.49-54
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• 2022

In Korea, companies which have work-related musculoskeletal burden works should have conducted legal risk assessments every three years from 2004 onwards. However, due to problems with the legal definition of work-related musculoskeletal burden works, some companies may have been exempted from the risk assessment even though their workers still experience work-related musculoskeletal pain. For example, the manufacturing process used by a particular semiconductor manufacturing company involved a great deal of legal musculoskeletal bueden works. However, this company eliminated the musculoskeletal burden works by continuously introducing automated processes, and finally, in 2016, all work which was legally defined as musculoskeletal burden work were removed from the company's manufacturing process. Nevertheless, in a 2016 survey, 9.6% of the company's workers still complained of musculoskeletal pain, and in a 2019 survey this proportion actually increased to 15.7%. This incident demonstrates the limitations and problems of the current legal risk assessment of work-related musculoskeletal burden work. Therefore, this study proposes two improvements to solve these problems. Firstly, it is necessary to broaden the current legal definition of work-related musculoskeletal burden works. For example, vibration risk factors and push/pull tasks that are currently missing from the definition should be included. Secondly, it is proposed that a survey on musculoskeletal pain should be conducted for all workers, regardless of whether they are engaged in musculoskeletal burden works. The results of this study could be used to improve the legal risk assessment of work-related musculoskeletal burden works.

• Journal of the Korean association of regional geographers
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• v.6 no.1
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• pp.1-28
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• 2000

The purpose of this study is to clarify the suburbanization of manufacturing, and location and linkages of decentralized manufacturing from Metropolitan Pusan by means of case study on manufacturing location and linkages in the suburb of Metropolitan Pusan. Kimhae city and Yangsan-Gun toward which heavy decentralization of manufacturing from the Metropolitan Pusan has been done. Both hard data and soft data were used as the basic data. Hard data are the statistical data in statistical yearbooks and firm list in directories. The former consists of the number of establishments and employees classified by product type, firm size and unit area. The latter consists of owner's names, addresses, employee number, products and headquarters of firms. Soft data are the results of the interviews with the 242 owners of firms in the four case study areas selected by Proportional Stratified Sampling Method. The major findings are as follows: 1. The spatial variations of manufacturing in the suburb was regularized in the latter half of 1970's. The primary processes to decentralize manufacturing from Metropolitan Pusan were the birth, relocation and establishment of branches of the firms. Among them the relocation of small outer-oriented single-location firms from Pusan was the most important. 2. The spatial variations undergoing spatial expansion of manufacturing distribution and increase of agglomeration degree of manufacturing, proceeded from the adjacents of Metropolitan Pusan to the outer areas along the main transportation route. 3. The main factors which caused manufacturing to decentralize from the Metropolitan Pusan were firm policy and land for this policy. The main locational factors which induced the decentralizing manufacturing into the suburb were land, market and transportation. 4. The strength of linkages with the outside of the study area is stronger than that of linkages with the inside. There is distance-decay-function in the strength of linkages with the outside, and linkages with short distant areas are stronger than those with long distant areas. 5. The ranges of spatial linkages in procurement of materials, in subcontraction and in marketing are wider than those in ordering. 6. The main factors which cause the formation of linkages are different by types of linkages: monopolistic and oligopolistic supply are important in procurement linkages; characteristics of products and the subsequent marketing difficulties, in subcontraction linkages; fluctuation, cost reduction, insufficient facility and characteristics of products, in ordering linkages; subcontract, characteristics of product and the subsequent marketing difficulties, in marketing linkages. 7. The changes of linkages owing to locational changes of firms were great, and were greater in long distant areas than in short distant areas. 8. The main factor influencing on the changes of linkages was the easiness in the transportation of goods, movement of labour and contacts with customers. In conclusion, some facts described above were proved to be consistent with the results of proceeding studies in the other areas: influence of relocation of decentralizing firms on the suburbanization; the factors of manufacturing decentralization; spatial characteristics of linkages; linkage changes owing to relocation of firms. Some were proved to be partly consistent: locational factors inducing decentralized manufacturing into the suburb were proved to be inconsistent. I think that the results of previous studies on the other areas can be applicable to the explanation on the decentralization of Metropolitan manufacturing from the viewpoint of the suburb. For the better explanation on the decentralization of Metropolitan manufacturing, more empirical case studies on the suburbanization of manufacturing are necessary.