관성 마찰용접 공정에서 심층 신경망을 이용한 업셋 길이와 업셋 시간의 예측

양영수(Young-Soo Yang),배강열(Kang-Yul Bae) 한국기계가공학회 2019 한국기계가공학회지 Vol.18 No.11

A deep neural network (DNN) model was proposed to predict the upset in the inertia friction welding process using a database comprising results from a series of FEM analyses. For the database, the upset length, upset beginning time, and upset completion time were extracted from the results of the FEM analyses obtained with various of axial pressure and initial rotational speed. A total of 35 training sets were constructed to train the proposed DNN with 4 hidden layers and 512 neurons in each layer, which can relate the input parameters to the welding results. The mean of the summation of squared error between the predicted results and the true results can be constrained to within 1.0e-4 after the training. Further, the network model was tested with another 10 sets of welding input parameters and results for comparison with FEM. The test showed that the relative error of DNN was within 2.8% for the prediction of upset. The results of DNN application revealed that the model could effectively provide welding results with respect to the exactness and cost for each combination of the welding input parameters.

X형 개선을 가진 후판 맞대기 용접에 있어서 유한요소법을 이용한 각변형 해석

양영수(Young-Soo Yang),배강열(Kang-Yul Bae) 한국기계가공학회 2018 한국기계가공학회지 Vol.17 No.4

Removal of angular deformation induced during the welding of butt joints in thick steel plates needs expert skill and is costly. To reduce deformation, proper joint designs are studied with a prediction of deformation prior to welding. However, as the thickness of a plate increases, a predictive analysis of the welding process is more difficult, especially if there is an increase in the number of welding passes in the joint. In this study, a numerical model with the finite element method (FEM) was developed to analyze the angular deformation in the multi-pass welding of butt joints of plates made of AH32 steel that had a thickness of up to 100 mm. A series of numerical simulations were then performed based on the developed model to predict the deformations for thick plates. With the results obtained by the analyses, this study suggested optimal X-shape grooves for the butt joints of thick plates to minimize the angular deformation. As the thickness of the plate increased to 100 mm, the ratio of the depth of the front-side groove to that of the back-side groove should be gradually increased to nearly 1:3.

자유곡면의 형상 측정에서 shape-from-shading을 접목한 스테레오 비전의 적용

양영수(Young-Soo Yang),배강열(Kang-Yul Bae) 한국기계가공학회 2017 한국기계가공학회지 Vol.16 No.5

Shape-from-shading (SFS) or stereo vision algorithms can be utilized to measure the shape of an object with imaging techniques for effective sensing in non-contact measurements. SFS algorithms could reconstruct the 3D information from a 2D image data, offering relatively comprehensive information. Meanwhile, a stereo vision algorithm needs several feature points or lines to extract 3D information from two 2D images. However, to measure the size of an object with a freeform surface, the two algorithms need some additional information, such as boundary conditions and grids, respectively. In this study, a stereo vision scheme using the depth information obtained by shape-from-shading as patterns was proposed to measure the size of an object with a freeform surface. The feasibility of the scheme was proved with an experiment where the images of an object were acquired by a CCD camera at two positions, then processed by SFS, and finally by stereo matching. The experimental results revealed that the proposed scheme could recognize the size and shape of freeform surface fairly well.

구속 링을 이용한 관 결합 공정의 응력해석

양영수(Young-Soo Yang),배강열(Kang-Yul Bae) 한국기계가공학회 2017 한국기계가공학회지 Vol.16 No.2

The pipe connection process using a clamping ring is used for joining small pipes in the refrigerator and air-conditioner industries instead of the brazing process, which induces inevitable thermal deformation in the pipes. However, few studies have been carried out on the process to select optimal parameters in joining pipes, and studies on the relation between the process parameters of the connection and connecting force of the joint have not been conducted. In this study, the connection process of pipes with the clamping ring was modeled using the finite element method (FEM) and analyzed to obtain the contact stress distribution between the pipes with which the connecting force of the joint was estimated. Considering the characteristics of pipe connection, the process was modeled and simulated in a two-dimensional axisymmetric solution domain. With the numerical model, the effect of ring shape on the connection was studied by adding a projection to the end of a ring or changing the length of a ring. The results of the analyses revealed that the contact stress distribution could be predicted with the suggested model. The effect of the ring shape was also presented. The effect of any combination of process parameters could be easily estimated through the related analyses.

제주도 부채(손바닥)선인장속(Opuntia) 두 분류군의 계통발생학적 유연관계

양영수(Young-Soo Yang),오홍식(Hong-Shik Oh) 한국자원식물학회 2021 한국자원식물학회지 Vol.34 No.5

In Jeju Island, there are two different types of Opuntia cactus in cladodae, fruit, flower, flowering period and spine. There is no comparative study of these two taxa yet, so it is often seen as the same species. The purpose of this study was to investigate the phylogenetic relationship between the Taxa of the Opuntia monacantha Haw. and Opuntia stricta Haw. in Jeju Island. The results indicate that the two taxa were completely different from each other on the analysis of nrITS, matK and atpB-rbcL gene as well as the morphological comparison. Also, O. monacantha among the two taxa is included in the Elatae series, so South America is the origin, and O. stricta is included in the Scheerianae series, which confirms that North America is the origin. The name of the O. monacantha in Jeju Island was named Jeju-Baick-nyun-cho considering geographical location conditions and symbolic characteristics.

K콘텐츠에 대한 중국소비자들의 경험이한국제품 구매의도에 미치는 영향

양영수(Young-Soo Yang),이재은(Jae-Eun Lee) 한국통상정보학회 2020 통상정보연구 Vol.22 No.4

비록, 일부의 선행연구들이 K콘텐츠가 한국제품 구매의도에 미치는 영향을 고찰했지만, 이들은 대부분 K콘텐츠의 단편적인 부분만을 고려하고 있다. 따라서 본 연구는 중국인 소비자들을 대상으로 K패션, K푸드, K드라마, K무비, K-POP 등 포괄적 측면에서 K콘텐츠에 대한 경험이 한국제품 구매의도에 미치는 영향을 실증분석하는 것에 목적이 있다. 연구가설 검증을 위해서 중국인 소비자들을 대상으로 설문조사를 실시하고 다중회귀분석을 실시한 결과 중국인 소비자들의 K패션, K푸드 그리고 K드라마에 대한 경험은 한국제품 구매의도에 유의한 정(+)의 영향을 미치는 것으로 나타났지만, K무비와 K-POP에 대한 경험은 한국제품 구매의도에 통계적으로 유의미한 영향을 미치지 못하는 것으로 나타났다. 이처럼 K콘텐츠에 대한 경험의 상이한 영향력을 검증했다는 점에서 본 연구의 결과는 중국인 소비자들에 대한 효과적인 마케팅 방안을 수립하는데 유의미한 시사점들을 제시할 수 있을 것이다. Although some studies on the purchase intention of K-contents and made-in products to be considered in this study have been conducted, studies that directly analyze the effect of the comprehensive K-contents experience on the purchase intentions of Korean-made products are insufficient. Therefore, the purpose of this study is to empirically analyze the effect of the experience of comprehensive K contents measured in K-fashion, K-foods, K-dramas, K-movies, and K-pop on the purchase intention of Korean products for Chinese consumers. To verify the research hypothesis, a questionnaire survey was conducted on 300 Chinese consumers and empirical analysis was performed using multiple regression analysis. As a result of the analysis, it was found that Chinese consumers experiences of K-fashion, K-food, and K-drama have a positive (+) effect on the purchase intention of Korean products, and K-movie and K-pop are insignificant in the purchase intention of Korean products. Based on the results of this study is expected to provide meaningful implications for establishing marketing plans for potential Chinese consumers.

최고경영진 및 사외이사의 정치적 연계와 연령이 해운물류기업의 국제화 성과에 미치는 영향

양영수 ( Yang Young-soo ),한가록 ( Han Ga-rog ),이재은 ( Lee Jae-eun ) 한국해운물류학회 2021 해운물류연구 Vol.37 No.3

본 연구는 최고경영진 이론을 바탕으로 해운물류기업 최고경영진 및 사외이사의 정치적 연계와 연령이 해운물류기업의 국제화 성과에 미치는 영향을 실증분석하였다. 1999년부터 2011년까지의 기간 동안 해운, 운송, 물류산업에 속한 19개 상장기업들의 균형패널데이터를 구축하여 패널회귀분석을 수행한 결과, 최고경영진과 사외이사의 정치적 연계는 해운물류기업의 국제화 성과에 유의한 정(+)의 영향을 미치는 것으로 나타났다. 반면 사외이사 연령은 해운물류기업의 국제화 성과에 유의한 정(+)의 영향을 미치는 것으로 나타났으나 최고경영진 연령은 해운물류기업의 국제화 성과에 유의한 영향을 미치지 못하는 것으로 나타났다. 본 연구는 선행연구들이 주목하지 않았던 정치적 연계 및 연령과 해운물류기업의 국제화 성과 간 연관성을 최고경영진 이론을 바탕으로 규명했다는 점에서 유용한 시사점을 제시할 수 있을 것이다. This study analyzed the political connections and age of the top management team and outside directors on the internationalization performance of shipping logistics firms. For 19 listed firms in the shipping, transportation, and logistics industries, balanced panel data for 13 years from 1999 to 2011 were established and panel regression analysis was performed. According to the analysis, the political connections of both the top management team and outside directors have a significant positive impact on the internationalization performance of shipping and logistics firms. On the other hand, the age of outside directors has a significant positive effect on the internationalization performance, but the age of the top management team does not significantly affect the internationalization performance of shipping and logistics firms. Based on upper echelons theory, this study could present useful theoretical, practical and politic implications in that it identified a link among political connections, age and internationalization performance that prior studies did not pay attention to.

큐폴라 용해로 철피의 열응력 및 피로수명 해석

양영수(Young-Soo Yang),배강열(Kang-Yul Bae) 한국기계가공학회 2020 한국기계가공학회지 Vol.19 No.2

Themo-mechanical analysis was carried out using the finite element method for the steel shell of a cupola furnace. When the outer surface of the shell was cooled with water to within the temperature range of 35–80 °C during operation of the cupola, the inner surface of the shell was expected to exhibit a temperature of 65 –248 °C based on heat transfer analysis. The shell was also expected to have an equivalent stress range of 100–280 MPa in the outer surface over the temperature range examined. Upon cooling the shell to obtain an outer surface temperature <80 °C, the maximum equivalent stress of the shell did not exceed the yield strength. Although the temperature of the outer surface varied between 35 and 80 °C periodically due to the cooling control problem, the fatigue stress at the outer surface of the shell was calculated to be within the fatigue strength. During a non-operational period to examine the system between furnace operations, the thermal stress presented in the shell was sufficiently low to reach the desired yield strength and fatigue limit.

해외경험의 깊이와 폭이 한국물류기업의 재무적 성과에 미치는 영향

양영수 ( Young Soo Yang ),이재은 ( Jae Eun Lee ) 한국해운물류학회(구 한국해운학회) 2014 해운물류연구 Vol.30 No.2

본 연구는 한국 물류기업을 대상으로 해외경험의 깊이와 폭이 재무적 성과에 미치는 영향을 실증 분석하고 있다. 해외경험과 성과 간의 관계에 대한 많은 선행연구들은 일관된 실증분석 결과를 제시하지 못하고 있다. 본 연구에서는 그 이유를 해외경험을 단일차원으로 고려했기 때문으로 보고, 조직학습이론에 따라 기업의 해외경험을 깊이(depth)와 폭(breadth) 등 두 가지 차원으로 구분하였다. 보다 구체적으로 본 연구에서는 해외경험의 깊이를 ‘기업이 최초로 특정 해외시장에 진출한 이후부터 현재까지 축적해온 해외사업 지식 및 경험의 정도’로, 해외경험의 폭을 ‘기업이 둘 이상의 다양한 해외시장에 진출함으로써 얻을 수 있는 해외사업 지식 및 경험의 정도’로 정의하고 이들이 물류기업의 재무성과에 미치는 영향을 실증 분석 하였다. 한국 상장기업들 중 수상 및 육상, 운송 서비스를 제공하는 19개 물류기업들을 대상으로 1980년부터 2006년까지의 기간 동안의 패널자료(494개의 기업-연도 관찰치)를 구축하여 실증 분석을 실시한 결과는 다음과 같다. 첫째, 해외경험의 깊이는 물류기업의 재무적 성과에 정(+)의 영향을 미치는 것으로 나타났다. 둘째, 해외경험의 폭 역시 물류기업의 재무적 성과에 정(+)의 영향을 미치는 것으로 나타났다. 이러한 실증 분석결과는 선행연구의 결과들과 일관되게 해외경험의 깊이가 외국인 기업으로서의 불리함(예컨대, 외국인 비용)을 감소시키며, 현지시장에서 필요로 되는 유용한 지식의 습득을 용이하게 함으로써 성과향상에 기여하며, 해외경험의 폭 역시 새로운 해외시장으로 진출하는 기업에게 현재의 상황에서 발생될 수 있는 복잡성을 줄여주고 프로세스를 단순화시켜줄 수 있도록 도움을 줄 수 있는 요인으로 작용함으로서 성과향상에 기여한다는 점을 시사한다. This paper analyzes the relationship between types of internationalization experience and financial performance of Korean logistics firms. Specifically, this research examines the types of international experience such as the depth of international experience and the breadth of international experience of Korean logistics firms. The depth of international experience is measured as the number of years since the focal firm’s first foreign expansion through foreign direct investment and it represents the years that took the firm to reach its current international expansion. The breadth of international experience is measured as the number of subsidiaries in which a firm established subsidiaries during its international expansion. Thus, we attempt to explain the types of international experience in terms of learning acquired in the course of past international activities and its impact on performance of the firms. Based on organizational learning theory, we presents two hypotheses. Hypothesis 1 suggests that a higher depth of accumulated experience in international markets will have a positive influence on the financial performance of Korean logistics firms. Hypothesis 2 anticipates that Korean logistics firm``s the diversity of international market experience is positively related to the financial performance of Korean Logistics Firms. Based on the sample of port logistics, land logistics, transportation service firms listed on the Korean Stock Exchange (KSE) for the period of 1980-2006, the results showed that the types of international experience of Korean logistics firms are positively related to financial performance of logistic firms. This paper investigates the relationship between the depth of breadth of international experience based on organizational learning theory. The results of our longitudinal study suggest that the types of international experience promotes the organizational learning by exposing the firm to rich and diverse experiences, and consequently have positive impact on firm``s performance.

Finite Element Analysis of the Effects of Process and Material Parameters on the LVDT Output Characteristics

Young-Soo Yang(양영수),Kang-Yul Bae(배강열) 한국기계가공학회 2021 한국기계가공학회지 Vol.20 No.9

Linear variable differential transformer (LVDT) is a displacement sensor and is commonly used owing to its wide measurement range, excellent linearity, high sensitivity, and precision. To improve the output characteristics of LVDT, a few studies have been conducted to analyze the output using a theoretical method or a finite element method. However, the material properties of the core and the electromagnetic force acting on the core were not considered in the previous studies. In this study, a finite element analysis model was proposed considering the characteristics of the LVDT composed of coils, core, magnetic shell and electric circuit, and the core displacement. Using the proposed model, changes in sensitivity and linear region of LVDT according to changes in process and material parameters were analyzed. The outputs of the LVDT model were compared with those of the theoretical analysis, and then, the proposed analysis model was validated. When the electrical conductivity of the core was high and the relative magnetic permeability was low, the decrease in sensitivity was large. Additionally, an increase in the frequency of the power led to further decrease in sensitivity. The electromagnetic force applied on the core increased as the voltage increased, the frequency decreased, and the core displacement increased.