• 펄프종이기술
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• 제33권2호
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• pp.24-31
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• 2001

As a novel method to improve strength properties of recycled test liner, Condebelt press drying system was introduced and adopted into Korea. New press drying treatment could enhance the surface and strength properties in accordance with the increase of sheet density. However, Condebelt drying can not increase the density of repeatedly recycled test liner as much as that of virgin UKP and at the same density condition, the strength of Condebelt press dried UKP is greater than that of press dried test liner. In order to increase the strength of test liner, two attempts were tried in this study. First, addition of polyelectrolytes, dry strength agent was investigated with a view to promote the fiber bonding potential of reclaimed corrugated container pulp. Second, blending effect of fines were analyzed in an aims of increasing density and strength of test liner. The results were as follows; Even in the case of test liner densified by Condebelt press dryer, addition of amphoteric PAM as a dry strength agent was effective in increasing strength properties and so the effect of dry strength agent on improving bonding potential of recycled OCC fiber could be confirmed. As an appropriate addition level of amphoteric PAM, below 1% based on dry pulp weight was suggested. Different from virgin UKP, density of recycled test liner can be increased by the blending of OCC fines and strength properties also can be improved. However, excessive blending of OCC fines could result in decreasing of density and serious weakening of test liner. The best blending ration of fines in test liner can be determined as about 30%. Taking into account the fines content in general OCC pulp as 50%, excessive 20% of fines were supposed to be fractionated and removed in order to achieve the best strength of Condebelt press dried test liner.

• 대한기계학회논문집A
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• 제31권11호
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• pp.1083-1092
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• 2007

The objective of the present paper is to evaluate the effect of the evolution of contact surface profile caused by fretting wear on fatigue life of press-fitted shaft by means of an analytical method based on experimental data. A finite element analysis was performed to analyze the stress states of press-fitted shaft, considering the worn contact profiles of shaft. The fatigue lives of the press-fitted shaft reflecting the evolution of contact stress induced by fretting wear were evaluated by stress-life approach using fatigue notch factor. It is found that the stress concentration of contact edge in press-fitted shaft decreases rapidly at the initial stage of total fatigue life, and its location shifts from the contact edge to the inside with increasing number of fatigue cycles. Thus the change of crack nucleation position in press-fitted shaft is mainly caused by the stress change of contact edge due to the evolution of contact surface profile by fretting wear. Furthermore, the estimated fatigue lives by stress-life approach at the end of running-in period of the fretting wear process corresponded well to the experimental results. It is thus suggested that the effect of fretting wear on fatigue life in press fits is strongly related to the evolution of surface profile at the initial stage of total fatigue life.

• 한국콘텐츠학회논문지
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• 제17권3호
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• pp.162-177
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• 2017

한국사회에서 뉴미디어가 확산되는 과정에서 언론이 뉴미디어 의제를 어떻게 다루었는지 분석하고, 언론의 정치적 성향에 따라 뉴미디어 정책에 대한 태도가 어떻게 나타나는지 사설에 대한 네트워크 분석을 실시했다. 분석 결과, 언론과 정부의 정치적 성향 일치 여부가 정부의 뉴미디어 정책에 대한 태도와 밀접한 관계가 있는 것으로 나타났다. 보수 정권이 집권한 시기에 보수 언론은 뉴미디어 정책을 지지한 반면, 진보 언론은 정부의 정책을 반대했다. 이용자 관점, 사회적 관점, 정책적 관점에서 뉴미디어 의제를 분석한 결과, 신문사들은 뉴미디어 도입에 대한 찬반 입장, 정책에 대한 설명 등 정책적 관점에서 주로 접근했다. 사설이 뉴미디어 정책 효과에 대한 언론사의 의견을 밝히고 여론을 형성하는데 영향을 미치는 공간임에도 불구하고, 뉴미디어 정책에 사설대한 언론의 태도가 정부의 정치적 성향과의 일치 여부에 따라 다르게 나타난 것은 심각한 문제라고 할 수 있다. 뉴미디어의 도입과 확산에 정부의 투자와 인력 등 많은 자본이 투입되는 만큼 언론의 비판적인 시각이 중요하기 때문이다.

• 산업공학
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• 제21권3호
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• pp.322-332
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• 2008

Digital Virtual Manufacturing is a technology to facilitate effective product developments and agile productions by digital model representing the physical and logical schema and the behavior of real manufacturing system, and it includes product, resources, processes and plant. For successful applications of this technology, a digital virtual factory as a well-designed and integrated environment is essential. In this research, we constructed a sophisticated digital virtual factory of a Korean automotive company's press shop. For efficient constructions of a digital virtual factory useful to kinematic simulations and visualizations, we analyzed entire business process and detailed activities of press engineering. Also, we evaluated geometries, structures, characteristics and motions of a plant and machines in press shop. The geometric model and related data of a virtual press shop are built and managed by a modeling standard defined in this paper. The virtual manufacturing simulation of press machines is conducted to evaluate kinematic motions, cycle time and locations of components using geometric models and related data. It's for interference checks and productivity improvements. We expect that this virtual press shop helps us to achieve great savings in time and cost in many manufacturing preparation activities in the new car development process of automotive companies.

• Journal of the Korean Wood Science and Technology
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• 제23권2호
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• pp.55-69
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• 1995

The primary objective of this research was to investigate optimum manufacturing condition of thin composite panels composed of sawdust, polyethylene film and polypropylene net. At the study the experiment was designed to make thin board in which sawdust offers effectiveness as core composing material, polyethylene as adhesive with added urea resin, and polypropylene as stiffness and flexibility in the composition panel. 100 types of thin composite panels were manufactured according to press-lam and mat-forming process of various hot pressing conditions(pressure, temperature and time). They were tested and compared with control boards on bending properties(MOR, MOE, SPL, WML), internal bond strength, thickness swelling, linear expansion and water absorption. At the same time the visual inspections of each types of panels were accomplished. The physical and mechanical properties of composite types passed by visual inspection were analyzed by Tukey's studentized range test. From the statistical analysis, the optimum manufacturing condition of thin composite panels were selected. Compared with two manufacturing processes, mat-forming process performed better than press-lam process in all tested properties. The optimum manufacturing conditions resulted from the experiment and statistical analysis were able to determine as following: the press temperature was shown the most good result at 130$^{\circ}C$ in mat forming process and 140$^{\circ}C$ press lam process, the press time 4 min in both processes, but the press pressure was 25-10kg/$cm^2$ in mat forming and 15k/$cm^2$ press lam process.

• 한국주조공학회지
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• 제41권4호
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• pp.342-348
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• 2021

거의 모든 철계 주조공장은 생압고철 (press scrap)을 주 장입재로 사용한다. 본 연구에서는 생압고철의 형상, 크기를 최적화하여 용해에너지를 절감하고자 하였다. 주조공장 두 곳의 3t/h 중주파 유도용해로를 활용하여 실험하였다. 개선 조건의 경우, 초기 장입 시에는 맞춤형 생압고철을 사용하였고, 추가 장입 시에는 소형 생압고철을 사용하였다. 개선 조건의 에너지 절감 효과를 높이기 위해, 회수철 표면의 청정화 공정을 강화하여 실시하였다. 개선 조건에 의한 용해에너지 원단위 (melting energy basic unit) 절감률은 두 주조공장에서 각각 23.3, 23.9%였고, 거의 유사하였다. 원단위 수준이 다른 두 곳의 주조공장 모두에서 개선 조건은 매우 효과적이었다. 개선 조건의 에너지 절감 원리 및 경제적 효과를 기술하였다.

• 문화기술의 융합
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• 제9권3호
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• pp.579-585
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• 2023

본 연구의 목적은 텍스트네트워트분석을 통해 스토킹에 대한 정치성향의 언론기사 내에 핵심 단어를 탐색하고 내재된 의도를 살펴보는 것이다. 2018년 1월 1일부터 2022년 12월 31일까지 보도된 보수언론기사(조선일보, 중앙일보) 824건, 진보언론기사(한겨레신문, 경향신문) 783건으로 총 1,607건을 선정하여 LDA(Latent Dirichlet Allocation) 기반의 토픽모델링 기법으로 도출된 주제범주의 양상을 탐색하였다. 연구결과는 보수언론과 진보언론의 공통된 토픽은 젠더폭력의 인식개선, 신변보호 및 처벌강도, 스토커 신상공개 도출되었고 두 언론의 상이한 토픽은 보수언론에서는 스토커의 가해행위, '신당역 살인사건'의 개요와 진보언론은 '신당역 살인사건'의 가중처벌요구, (사이버공간의) 성착취 범죄 근절로 구성되었다. 본 연구는 스토킹에 대한 언론기사 간의 이념적 의견에 따라 보도형태에 변화가 있음을 시사한다.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2008년도 추계학술대회 논문집
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• pp.43-44
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• 2008

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2012년도 추계학술대회 논문집
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• pp.291-292
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• 2012

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 1992년도 춘계학술대회 논문집 92
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• pp.1-10
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• 1992

Press is one of the most dangerous machine among the hazardous machinery. So, the apparatus of low cost automation is suggested to supply circumferential workpieces to press. And the apparatus is mocked up to apply practically.