• 한국공간구조학회논문집
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• 제23권3호
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• pp.87-94
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• 2023

Chloride is one of the most common threats to reinforced concrete (RC) durability. Alkaline environment of concrete makes a passive layer on the surface of reinforcement bars that prevents the bar from corrosion. However, when the chloride concentration amount at the reinforcement bar reaches a certain level, deterioration of the passive protection layer occurs, causing corrosion and ultimately reducing the structure's safety and durability. Therefore, understanding the chloride diffusion and its prediction are important to evaluate the safety and durability of RC structure. In this study, the chloride diffusion coefficient is predicted by machine learning techniques. Various machine learning techniques such as multiple linear regression, decision tree, random forest, support vector machine, artificial neural networks, extreme gradient boosting annd k-nearest neighbor were used and accuracy of there models were compared. In order to evaluate the accuracy, root mean square error (RMSE), mean square error (MSE), mean absolute error (MAE) and coefficient of determination (R2) were used as prediction performance indices. The k-fold cross-validation procedure was used to estimate the performance of machine learning models when making predictions on data not used during training. Grid search was applied to hyperparameter optimization. It has been shown from numerical simulation that ensemble learning methods such as random forest and extreme gradient boosting successfully predicted the chloride diffusion coefficient and artificial neural networks also provided accurate result.

• 한국표면공학회지
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• 제34권5호
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• pp.475-480
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• 2001

Diffusion of Cu into the low-k para-xylene based plasma polymer (pXPP) thin films deposited by plasma-enhanced chemical vapor deposition using the para-xylene precursor was comparatively measured using various methods. Cu layer was deposited on the surfaces of pXPPs treated by $N_2$ plasma generated in a magnetically enhanced inductively coupled plasma reactor. Diffusion characteristics of Cu into pXPPs were measured using Rutherford backscattering spectroscopy (RBS), secondary ion mass spectroscopy (SIMS), cross-sectional transmission electron microscopy (XTEM), and current-voltage (I-V) measurements for the vacuum-annealed Cu/pXPPs for 1 hour at $450^{\circ}C$ and were compared. The results showed a correlation between the I-V measurement and SIMS data are correlated and have a sensitivity enough to evaluate the dielectric properties but the RBS or XTEM measurements are not sufficient to conclude the electrical properties of low-k dielectrics with Cu in the film bulk. The additional results indicate that the pXPP layers are quite resistant to Cu diffusion at the annealing temperature of $450^{\circ}C$ compared to the other previously reported organic low-k materials.

• Journal of the Korean Society for Industrial and Applied Mathematics
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• 제9권2호
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• pp.29-43
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• 2005

We consider a surface reconstruction problem from geometrical points (i.e., points given without any order) distributed on a series of smooth parallel cross sections in ${\mathbb{R}}^3$. To solve the problem, we utilize the natural points ordering method in ${\mathbb{R}}^2$, described in [18], which is a method of reconstructing a curve from a set of sample points and is based on the concept of diffusion motions of a small object from one point to the other point. With only the information of the positions of these geometrical points, we construct an acceptable surface consisting of triangular facets using a heuristic algorithm to link a pair of parallel cross-sections constructed via the natural points ordering method. We show numerical simulations for the proposed algorithm with some sets of sample points.

• 한국가구학회지
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• 제18권2호
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• pp.138-142
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• 2007

Optical microscope was used to observe the difference of safranine penetration in Pinus densiflora, Pinus rigida, Pinus koraiensis and Larix kaempferi grown in Korea. It was found that Pinus koraiensis contained the highest number of ray parenchyma and ray tracheids. In longitudinal direction, latewood penetration was found higher than that of earlywood. The number of resin canals was found highest in Pinus koraiensis and lowest in Pinus rigida. The resin canal conducted safranine higher than longitudinal tracheids. In longitudinal direction, safranine diffused from longitudinal tracheid to ray parenchyma through the cross-field pits and from the longitudinal resin canal to ray parenchyma or longitudinal tracheid. Safranine diffused from longitudinal tracheid to its neighboring tracheid through bordered pit or ray parenchyma through the cross-field pits.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2000년도 춘계학술대회논문집
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• pp.1416-1422
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• 2000

The cross-flow fans have been widely used to constitute the air moving systems in many air-ventilating and air-conditioning devices. The cross-flow fan system has many design parameters which have crucial influence on the performance and the noise characteristics of the devices. As a result, there are many difficulties in the design stage of the devices and the general design guide has not been sufficiently established yet. This study presents the experimental results of the parametric investigation of some chosen design parameters, which are the shape of the stabilizer, the profile of the scroll casing, and the diffusion angle of the flow exit. The results are expressed as the fan performance and the specific sound pressure level characteristic. These parts have been found to have crucial effects on the system performance/noise characteristics and should be considered with care in the design stage.

• 한국화재소방학회:학술대회논문집
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• 한국화재소방학회 1997년도 International Symposium on Fire Science and Technology
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• pp.169-177
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• 1997

An experimental study has been conducted at an intermediate scale to study the effect of a cross flow on a purely buoyant fire. Video taping of the flame and post processing of the images by means of a novel technique provide a contour of a mean flame for all cases studied. This flame contour allows the determination of a mean flame length and a mean flame height. The mean flame length and height are recorded as functions of the forced flow velocity. Three dimensional flow patterns are formed in the flame trailing edge affecting both the mean flame length and height. The three dimensional patterns are studied systematically as functions of the cross flow velocity to quantify the effect of confinement on the flame geometry.

• 마케팅과학연구
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• 제8권
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• pp.515-535
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• 2001

본 연구는 인간 유전자를 해독하려는 경주가 어떻게 전개되어왔는가에서 시작하여 생명공학 혁신들이 나타나고 시장 창출이 이루어지고 있는 분야들이 어떠한 것이 있는가에 대한 연구를 하였다. 의학/의약 분야, 농업/식품 분야, 화학/공정 분야, 환경분야, bioelectronics 분야 등에서 혁신 창출이 이루어지고 거대한 시장이 창출되어가고 있음을 탐색하였다. 그리고 나타나는 생명공학 혁신의 시장확산의 성공에 관한 연구 분야를 경쟁력에 관한 이론, 혁신의 소비자 수용과 확산에 관한 문헌들을 중심으로 하여 제시하였다. 클러스터를 잘 형성할 수록, 제휴를 통한 보완관계를 잘 형성할수록 혁신 창출과 확산에서 성공가능성이 높을 것 이다. 그리고 생명공학 분야는 기술과 시장의 양 측에서 벤처 창업에서 시간이 경과함에 따라 기술에서 시장으로 무게 중심이 점차적으로 옮겨갈 것이라고 제기하였다 생명공학과 같은 첨단기술 분야에서 혁신 확산이 제대로 이루어지려면 핵심역량을 창출하는 과정에서 기업가의 전략적 의도를 제대로 형성하는 것이 중요한 것이라는 것을 제기하였다. 생명공학 분야에서 나타나는 혁신의 소비자 수용과정에서 저항이 예상되며, 이는 기존의 습관과 지각된 위험이라는 변수에서 지각된 위험이라는 변수가 더 강하게 작용할 것이라고 제기하였다. 생명공학 분야에서 혁신의 소비자 수용과 확산에 관한 조사에서는 양적 조사보다 질적 조사가 중요하며 이는 앞으로 창출되어야하는 시장조사이기 때문이다. 생명공학에서의 혁신에 대한 소비자 수용과 확산은 소비자들이 형성하고 있는 사회네트워크의 성격이 영향을 미친다. 소비자들이 약한 연결로 많은 네트워크를 가지고 있는 소비자집단 사이로 혁신이 전달 될수록 확산이 빠르게 나타난다. 글로벌 혁신확산 영역에서는 생명공학과 같은 첨단기술 분야에서는 문화적인 영향을 적게 받을 것이라는 명제를 제기하였다. 이러한 이론적 연구가 앞으로 실증적 연구로 나타나 보다 일반화된 이론으로 발전하는 것은 미래의 연구로 돌린다.

• 한국터널지하공간학회 논문집
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• 제21권1호
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• pp.115-126
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• 2019

최근 도심지 차량 정체 해소와 주변환경을 개선하기 위하여 도심지 지하공간을 활용하는 대심도 복층터널 설계 및 시공 기술개발 연구가 진행되고 있으며, 네트워크형 복층터널은 단면이 작고, 평지 하부에 시공됨에 따라 입 출구의 경사가 가파른 특징이 있는 교차로 형태를 가지며 화재발생시 화재연기가 매우 빠르게 전파되어 인명피해 발생이 우려된다. 따라서 본 연구에서는 교차로에 화재연기 확산지연장치를 설치한 경우와 미설치된 경우에 대하여 화재연기 확산지연효과를 분석하였다. 화재연기 확산지연장치를 교차로에 설치하였을 시 화재발생 후 270초까지 화재연기가 지연되었으며, 화재연기 확산지연장치의 차단면적이 커질수록 인명피해 예방에 도움이 될 것으로 분석되었다.

• 통상정보연구
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• 제19권1호
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• pp.3-21
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• 2017

최근 급속히 확산되고 있는 '전자상거래무역' 혹은 '국경을 넘는 전자상거래(CBEC)'에 대하여 우리정부는 수출증대에 미치는 영향이 크다는 판단하에 적극적인 지원을 하고 있다. 그러나 다양한 부처에서 산발적으로 추진되는 지원은 효과적이지도 효율적이지도 못한 실정이다. 따라서 지원정책의 일관성과 효과성, 효율성을 높이기 위해서는 법률적으로 주무부처를 명확히 하고 타부처에 대하여는 협조의무를 부여하는 방안이 바람직하다. 이를 위해서는 기존에 부처별 업무영역에 따라 산재되어 있는 법률들을 각각 개정하거나 새로운 법률의 제정을 해야 한다. 그러나 이는 현실적으로 실행하기가 쉽지 않기 때문에 기존 법률 중 가장 유사한 영역을 규정하고 있는 '전자무역 촉진에 관한 법률'을 개정하는 것이 실현가능한 대안으로 판단된다. 본 연구에서는 CBEC를 확산하기 위하여 이 법률의 개정을 하는 것이 다른 방안에 비하여 합리적이라는 점을 다양한 문헌자료를 통하여 제시하여 우리나라 CBEC의 확산, 특히 CBEC 수출의 확대에 기여하는 것을 연구의 목적으로 삼는다.

• 비교문화연구
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• 제37권
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• pp.7-29
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• 2014

The 'discovery' or 'conquest' of the New World in 1492 was the starting point of world history that irrevocably changed the fate of the Latin American continent. The global stream known as 'Columbian Exchange', which was the widespread inter-continental contacts, inter-civilizational conflicts, or bilateral communication, has rendered multifarious effects throughout many historical periods up to the very contemporary time. The propagation of Catholicism initiated along with this 'discovery' transformed Latin America of nowadays in the region that has the biggest Catholic population in the world. The previous studies in Korea regarding Latin American Catholicism has focused on the spread of Catholicism in relation to the European colonization, rather than analyzing the concrete and detailed ways in which Catholicism exerted tremendous influences in the whole continent. They were less attentive to various historical contexts in which the diffusion of Catholicism differed greatly according to cultural landscapes and political specificities. Thus, this essay attempts to examine the diffusion of Catholicism from the perspective of confrontation between royal authorities and the power of church. The essay points out that the royal communities and institutional authorities which facilitated the intial process of Catholic evangelization maintained antagonistic relationship with ecclesial powers. By delving into the gradual transformation of church systems, it reveals that Catholicism in Latin America became a major field for conquerors in power to attain economic and political dominance. And unlike the initial submission and hospitality, the religious convert of the indigenous people attested to the violent inhumanity and opposition. Therefore, the essay aims to pave a clearer way to the understanding of complicated dynamics and conflicts between Catholicism in Latin America and the establishment of Spanish colonization.