이중으로 텍스쳐 된 표면에 충돌하는 액적의 동적 특성

문주현 ( Joo Hyun Moon ),이성혁 ( Seong Hyuk Lee ) 한국분무공학회 2016 한국액체미립화학회지 Vol.21 No.1

This study presents the dynamic characteristics of an impinging droplet on hydrophobic and hydrophilic surfaces with various texture area fractions. The flat surface was fabricated by using the drilling technique to make micro-meter hole-patterned surfaces, which shows hydrophobic textured surfaces. Moreover, the hydrophilic textured surfaces were manufactured by anodizing technique on the micro-meter hole-patterned surfaces to generate multi-layer surfaces. Impinging droplet experiments were conducted for various hole-patterned surfaces, with changing impact velocity and texture area fractions. It is observed that an anodizing technique increases wettability by decrease in hole diameter on the textured surfaces. However, micro-drilled surfaces decreases wettability because the hole diameter was so large that air can be trapped under the holes. In addition, the maximum spreading diameter decreases with the texture area fraction for the micro-drilled surfaces because of decrease in wettability.

시스템반도체산업의 기술혁신패턴의 진화에 대한 연구

문주현(Joo Hyun Moon),박규호(Kyoo-Ho Park) 한국기술혁신학회 2011 기술혁신학회지 Vol.14 No.2

본 연구는 시스템반도체의 기술혁신패턴의 진화를 지식의 생성방식의 진화와 이에 따른 기업간 관계의 진화라는 관점에서 분석하였다. 특히, 설계도구인 EDA의 등장 이후에 지식의 생성방식이 변화하였고 이를 기반으로 기업유형의 진화, 기업간 관계의 진화 등 기술혁신패턴이 진화하였음을 문헌자료에 대한 검토와 주요 기업에 대한 인터뷰를 통해 분석하였다. 분석결과는 다음과 같다. 첫째, 시스템반 도체의 혁신활동은 과거 지식의 축적을 통한 설계활동 중심의 기술개발에서 지식 및 기술활용을 위한 탐색활동 중심의 혁신활동으로 진화하고 있다. 즉, 특정 기능의 구현을 통한 제품개발이 아니라 IP를 활용한 시스템 구축으로 제품개발이 이루어지는 설계활동의 분업화로 지식과 기술의 탐색활동이 중요해지고 있다. 둘째, 지식의 가치가 높아짐에 따라서 지식을 통한 신시장의 창출과 기업간 관계를 통한 신산업, 신기술의 개발이 일어나고 있다. 동시에 기존의 설계활동보다 설계비용 절감과 설계기간이 단축되면서 시장과 기술의 진화에 더욱 효과적으로 대응할 수 있는 기업유형으로 전문적 분업화가 일어나고 있다. 셋째, 지식의 활용측면이 점차적으로 강조됨에 따라 기업간 네트워크는 다른 기업과의 상호 보완적인 기술개발구조를 구축하기 위해 다양하게 형성되고 있다. 이러한 논의는 국내외 기업간 네트워크를 전략적으로 활용하고, 시장창출과 지식활용 등 탐색활동을 위한 제반 전략이 강구되어야 함을 시사한다. This paper tries to analyze the evolution of technological innovative pattern in system semiconductor industry from the perspective of the evolution of way by which knowledge is generated and its related evolution of inter-firm relationships. In particular, this paper focuses on the evolution of knowledge after the emergence of EDA as a design tool, as a main momentum. As a result of analysis, we can find out following things. First, the innovative activities have evolved from design activity-centered technology development to innovative activities focusing on searching activities for utilizing knowledge and technology. Second, with rising value of knowledge, creation of new market utilizing knowledge, and development of new industry and new technology through inter-firm relationship had been made, in addition to strengthened specialized technological division of labor. Third, with focusing on utilization of knowledge, inter-firm network has taken diverse forms for building complementary platform for co-development. This discussion can give an insight on the necessity of utilizing inter-firm network strategically and setting strategies for enhanced searching activities such as market creation and knowledge utilization.

입자 군집 최적화 기법을 적용한 판-휜 열교환기 열-경제성 최적 설계

문주현(Joo Hyun Moon),이균호(Kyun Ho Lee),한동인(Dong In Han) 대한기계학회 2021 대한기계학회 춘추학술대회 Vol.2021 No.5

The present study investigates a multi-variables thermal-economic optimization problem of a crossflow plate-fin heat exchanger (PFHE). An approach of the PSO algorithm was utilized to obtain better estimation accuracy and faster convergence. To verify the improved search performance of the PSO approach, the optimization results were compared under the same constrained search space. We considered single objective functions of the number of entropy generation units (NEGUs) based on the ε-NTU procedure. As a result, the present study proved that the PSO method can provide more efficiency in finding optimal solutions quickly with improved convergence for the thermal-economic design problem of the crossflow PFHE, which also will be useful to industries and engineers.

분무응용 기술 : 표면 형상에 따른 액적의 퍼짐과 수축 특성

문주현 ( Joo Hyun Moon ),이성혁 ( Seong Hyuk Lee ) 한국액체미립화학회 2015 한국액체미립화학회 학술강연회 논문집 Vol.2015 No.-

This study presents the spreading and receding characteristics of a droplet impinging on the hydrophobic and hydrophilic surfaces with different morphology. The flat surface was manufactured by using the microdrilling technique to fabricate micro-meter holes, leading to make hydrophobic textured surfaces. In addition, the hydrophilic textured surfaces were made from the nano-sized anodizing technique on the micro-drilled surfaces to make hybrid hydrophilic textured surface. We conducted experiments for various textured surfaces with respect to morphology including hole depth and diameter. The spreading and receding characteristics were examined with respect to the impact velocity and area fraction of the textured surfaces. As results, an anodizing technique decreases contact angle by decreasing hole diameter which changes dynamic wettability on the textured surfaces. However, micro-drilled surfaces decreases wettability because the hole diameter was large. In addition, the contact diameter decreases with the texture area fraction for the micro-drilled surfaces because of little liquid penetration. The dynamic contact angles were also higher when the textured area fraction increases on micro-drilled hydrophobic surfaces.

시뮬링크와 심스케이프를 활용한 배터리팩 발열 및 냉각장치 설계

문주현(Joo Hyun Moon),이균호(Kyun Ho Lee),김명진(Myeongjin Kim) 대한기계학회 2022 대한기계학회 춘추학술대회 Vol.2022 No.11

포스터 전시회 : 가열된 표면 위에서 충돌하는 뉴턴과 비뉴턴 액적의 동적 거동

문주현 ( Joo Hyun Moon ),정찬호 ( Chan Ho Jeong ),이여해 ( Yeo Hae Lee ),이진운 ( Jin Woon Lee ),김주헌 ( Jooheon Kim ),유홍선 ( Hong Sun Ryou ),이성혁 ( Seong Hyuk Lee ) 한국액체미립화학회 2013 한국액체미립화학회 학술강연회 논문집 Vol.2013 No.-

This article illustrates the temperature dependent spreading and receding characteristics of a Newtonian and a non-Newtonian droplet impact on a heated solid surface at different Weber numbers with surface temperatures. To make non-Newtonian droplets, a xanthan gum solution was used with different concentrations. From a high-speed camera images, spreading and receding diameters were captured during the impact process. For impact velocity and solid surface temperature, distinct differences in spreading and receding motions were found between Newtonian and non-Newtonian droplets. If a solid surface temperature increases, the maximum spreading diameter slightly increased at DI-water droplet whereas the maximum spreading diameters of xanthan gum droplets were similar for all surface temperatures. This is due to viscosity change on thin liquid lamella contact with heated surface. The receding phenomena could be clearly distinguished on the heated surface. The retraction rate of a xanthan gum droplet increased by increase Weber number whereas DI-water droplets were constant. Because both shear thinning and heat affected liquid lamella influenced a droplet receding, shear viscosity of the xanthan gum droplets decreased faster than the DI-water.

기열표면에 충돌하는 액적의 열전달 특성

문주현 ( Joo Hyun Moon ),이성혁 ( Seong Hyuk Lee ) 한국액체미립화학회 2014 한국액체미립화학회 학술강연회 논문집 Vol.2014 No.-

In this study, we experimentally studied heat transfer characteristics to investigate temporal evolution of solid and liquid surfaces. By using high-speed camera images, the spreading and receding images were taken to investigate dynamics and heat transfer of the droplet. As a droplet impinges on a heated surface, it receded faster whereas spreading diameters were almost similar with temperatures until maximum spread. On the basis of the transient heat conduction theory, the temporal evolution of solid temperature at the impact point was estimated, and the thermal energy absorbed and droplet mean temperature were calculated. The mean droplet temperature increased significantly at the spread phase, however, the receding droplet temperature increased slowly. This would be because a contact line speed is much faster, as well as the temperature difference between a droplet and a solid surface is much higher at the spread phase.

시뮬링크와 심스케이프를 활용한 배터리팩 발열 및 냉각장치 설계

문주현(Joo Hyun Moon),이균호(Kyun Ho Lee),김명진(Myeongjin Kim) 대한기계학회 2022 대한기계학회 춘추학술대회 Vol.2022 No.11

다공성 촉매를 고려한 단일튜브 내의 수증기-메탄 개질에 관한 수치해석 연구

문주현(Joo Hyun Moon),이성혁(Seong Hyuk Lee),윤기봉(Kee Bong Yoon),김지윤(Ji Yoon Kim) 한국가스학회 2014 한국가스학회지 Vol.18 No.4

본 연구에서는 촉매가 들어있는 고정층 반응로의 단일 개질관에 대하여 전산 유체 해석(Fluent ver. 13.0)을 수행하여 열/유동 특성을 파악하고, 주입 가스에 따른 추출 가스의 종류를 다공성에 따라 예측하였다. 촉매 형상을 모델링하기 위하여, 개질관 내부에 있는 촉매를 모두 다공성 물질이라고 가정하고, 수정된 Eugun 식을 해석에 적용하였다. 유체의 공극률을 기준으로 0.545, 0.409, 그리고 0.403로 설정하고, 결과를 비 다공성인 경우와 비교하였다. 수치해석 결과, 개질관 벽면의 온도는 흡열반응과 주변 열전달로 인하여 개질관의 온도보다 높게 나타나며, 수소 생성량도 다소 증가했다. 촉매의 공극률이 증가 하게 될 경우, 압력강하로 인하여 관 중심부 온도 및 수소 생성량이 현저하게 감소하는 경향을 보였다. The present study investigated numerically heat and mass transfer characteristics of a fixed bed reactor by using a computational fluid dynamics (CFD) code of Fluent (ver. 13.0). The temperature and species fraction were estimated for different porosities. For modeling of the catalyst in a fixed bed tube, catalysts were regarded as the porous material, and the empirical correlation of pressure drop based on the modified Eugun equation was used for simulation. In addition, the averaged porosities were taken as 0.545, 0.409, and 0.443 and compared with non-porous state. The predicted results showed that the temperature at the tube wall became higher than that estimated along the center line of tube, leading to higher hydrogen generation by the endothermic reaction and heat transfer. As the mean porosity increases, the hydrogen yield and the outlet temperature decreased because of the pressure drop inside the reformer tube.

일반논문 : 북한 우라늄농축프로그램의 기술적 타당성 및 잠재적 위험 평가

문주현 ( Joo Hyun Moon ) 동국대학교 북한학연구소(구 동국대학교 안보연구소) 2011 북한학연구 Vol.7 No.1

2010년 11월 방북한 해커 박사는 우라늄농축시설과 건설 중인 경수로 실험로를 목격하고, 이를 세계에 공개하였다. 해커 박사가 공개한 바에 따르면, 북한은 최신 우라늄농축시설을 건설완료 하고, 경수로 실험로를 건설하고 있었다. 북한은 우라늄농축시설이 경수로 실험로의 핵연료 공급 목적이라고 주장하였다고 한다. 해커 박사가 방북시 목격담을 정리한 자료로부터 북한 UEP에 대한 윤곽을 파악하고, 해커 박사의 목격담과 북한의 주장에 대한 기술적 타당성을 평가하였다. 이를 토대로 북한의 UEP가 진전될 경우, 동북아를 비롯하여 세계 안보에 미칠 수 있는 잠재적 문제점으로서, 핵무기 프로그램으로의 전용가능성, 핵물질 이전 가능성, 원자력사고의 가능성 등을 살펴보았다. Dr. Hecker who visited North Korea on November 2010 made an on-site observation of the uranium enrichment facility and the experimental light water reactor (LWR) under construction and made it public to the world. According to the Hecker`s observation, the North completed the construction of the uranium enrichment facility and is constructing the experimental LWR. The North claimed that the enrichment facility is to provide the nuclear fuel for the experimental LWR. This paper reviewed the technical feasibility of the North`s statements related to the experimental LWR and the uranium enrichment facilities, which were reported by Dr. Hecker. Also it evaluated the potential risks of the North`s uranium enrichment program in terms of possibilities of diversion to the nuclear weapon program, illicit transfer of nuclear material, and nuclear accident occurrence.