Direct fabrication of copper patterns by reactive inkjet printing

김국주,안성일,최경철 한국물리학회 2013 Current Applied Physics Vol.13 No.9

Reactive inkjet printing (RIP) was applied to fabricate arbitrary copper (Cu) patterns. RIP prints reactive inks which can provide desired materials after the reaction on a substrate. Here, Cu precursors and reducing agents were dissolved together in one solution as a printable ink instead of conventional Cu nanoparticle inks. The prepared reactive ink was applied to the RIP method to provide dot arrays, lines,and films of Cu. The synthesis of Cu was confirmed to occur successfully by thorough analysis. The RIP method can reduce the process cost and resolve critical drawbacks of the conventional inkjet printing such as a nozzle clogging problem. Furthermore, utilizing reactive precursor inks broadens the choice of materials that can be processed by inkjet printing.

Nanomaterial-based stretchable and transparent electrodes

김국주,현병관,장지욱,조은진,박영근,박장웅 한국정보디스플레이학회 2016 Journal of information display Vol.17 No.4

The recent advent of unprecedented wearable applications engendered the need for stretchable electronics, which can be realized by making the individual components stretchable. The transparent conducting electrode is one of the most important components of optoelectronic devices. Therefore, developing transparent electrodes in a stretchable form is essential for the implementation of stretchable electronics. In this paper, the recent efforts in the development of stretchable and transparent electrodes, particularly those using nanomaterials such as metal nanowires, metal nanofibers, and carbon nanotubes are introduced.

풍력발전용 요 베이링 제조기술

김국주,이진모,김남용,김태옥,박영준,염종택 한국소성가공학회 2010 한국소성가공학회 학술대회 논문집 Vol.2010 No.5

기부대양여 사업에 의한 군사시설 이전의 리스크 요인 도출 및 우선순위 평가

김국주,안성진,박영준 한국건설관리학회 2020 한국건설관리학회 논문집 Vol.21 No.3

The endowment and concession has been put to practical use for the relocation projects of military Facilities. Yet, in terms of the project implementation, delay of a great deal of the projects is occurring due to related regulations and standards, as well as a lack of mutual understanding between project implementers and military units. This study analyzes the risk factors by identifying and prioritizing the potential risk factors at each stage of project implementation such as the issues that limit project characteristics and implementation. Among the derived risk factors, request exceeding facility standards in the licensing and design phases, opposition to troop relocation in the project approval phase, design change during construction phase in the construction and completion phases, dissenting opinions on endowed/conceded property in the property disposal phase and absence of facility standards in the MOA conclusion phase were found to be the main object of consideration in risk management. This study is expected to provide project managers with a guideline for effectively pursuing the projects, as it provides prioritization and optimization of risk management.

의사결정론을 통한 EMP 방호대책 및 수준 판단방안 제시에 관한 연구

김국주,박상우,백장운,박영준 한국건축시공학회 2019 한국건축시공학회지 Vol.19 No.2

한반도 안보상황에서 주변국들에 의한 EMP 위협이 고조되는 상황에서 EMP 방호시설은 군의 작전수행능력을보장할 수 있는 매우 중요한 수단이다. 이러한 EMP 방호시설은 작전을 수행하는 부대의 다양한 요소들을 종합적고려하여 구축하여야 한다. 하지만 현 군·관의 EMP 방호기준은 80dB의 일률적인 차폐효율만을 요구하고 있다. 본 연구에서는 전문가 집단의 의견을 통해 객관적이고 통계적 방법을 사용하여 방호요구수준의 고려사항을 재선정하고자 한다. 연구방법은 델파이기법을 사용하였으며, 53명의 EMP방호 설계기준과 관련 있는 전문가들을 선정하였다. 1차 설문은 EMP 방호의 적정수준에 대하여 조사하였고, 2차 설문은 방호대책 수립시 고려요소에 대하여 분석하였다. 채택된 전문가의 의견에 대해 요인분석을 실시한 결과, EMP 방호요구수준 설정시 METT+TC 요소를고려하여야 한다는 것을 확인하였다. In the context of increasing threats of EMP by neighboring countries in the security situation on the Koreanpeninsula, EMP protection facilities are a very important means of ensuring military operational capability. These EMPprotection facilities should be constructed by comprehensively judging various factors about operation units. However,Defense Military Facilities Criteria and National Technical Guideline for EMP protection require at least 80dB shieldingeffectiveness without considering other options. In this study, we use objective and statistical methods to refine theconsideration of the required EMP protection level based on the opinions of the experts. To do this, the Delphitechnique is used for this study, and the survey was conducted from 53 experts related to EMP protection standardin the military and civilian sectors. The first questionnaire investigated the appropriate level of EMP protection, andthe second questionnaire analyzed the factors considered in establishing EMP protection level. As a result of thefactor analysis on the opinions of the experts, it was concluded that the EMP protection requirement level should bedetermined by variables of METT + TC.

Al6061 Bulk재에서 압축시험에 의한 상온가공성 분석 및 마찰인자 측정

김국주,박종수,윤존도 경남대학교 신소재연구소 2003 신소재연구 Vol.15 No.2

부피성형(bulk forming)은 가공속도, 소재 회수를 및 가공 후의 조직 미세와 등의 유리한 점이 많아 대량 생산에 적합한 가공 방식이다. 그러나 금형형상과 가공조건들이 적절하지 못할 경우 형상오차 및 연성파괴 등의 성형결함이 발생하게 된다. 이 성형결함 없이 성형될 수 있는 한계를 부피 성형한계(bulk forming limit)라고 하는데, 이것은 가공성(workability)과 의미가 비슷하다. 가공성은 공정종류 금형과 소재사이의 마찰, 변형속도 등에 의해 좌우되므로 예측하기 어렵다. 따라서 본 실험에서는 가공성을 Al6061의 소재에서 가공온도, 마찰 및 변형을 속도에 따른 성형한계도(forming limit diagram)로 작성하여 정량화하고자 하였다. 또 압축시험에서 금형과 소재사이의 마찰효과에 의한 베럴링(barreling) 현상이 생기므로 신빙성 있는 실험결과를 얻기 힘들다. 따라서, 각 마찰조건에서 링 압축시험을 통한 마찰인자를 구해서 압축시험으로 구한 측정웅력을 보정하여 유동웅력(flow stress)을 구하는데 사용하고자 한다. Bulk forming process is widely used for a large plastic deformation in a metal industry, which has a lot of advantages at processing speed, raw material utilization, fine microstructure, etc. But if die shape and process conditions are selected improperly, forming defects can be found due to geometric errors and ductile fracture. Bulk forming limit is defined as it is deformed without these defects which is similar to the workability. Prediction of workability is difficult because of dependence on a type of processes, friction of die and material, deformation rate, etc. Therefore, in this study, forming limit diagram is made depending on forming temperature, friction and strain rate to analyze the workability of A16061 bulk material. Also, it is difficult in measuring of reliable result exactly because the barreling is caused by interfacial friction between die and material at the compression test. So, friction factor is measured at the different friction conditions by ring compression test and then flow stress will be calculated from the measured stress by compression test.

시론 : 진정한 과거 반성 없이는 미래가 없다 -광복 60주년에 부치는 글

김국주 평화문제연구소 2005 통일한국 Vol.260 No.-

제16회 한일어촌어항어장기술교류회의 - 갯벌산업 선진화 방안

김국주,Kim, Guk-Ju 한국어촌어항협회 2013 어항어장 Vol.101 No.-

유한요소해석을 이용한 한국군 K-1전차하중에 대한 아스팔트 포장재의 Top-down 균열 거동에 대한 연구

김국주,천상현,박봉석,김주희 육군사관학교 화랑대연구소 2016 한국군사학논집 Vol.72 No.1

In this study, a Finite Element (FE) model was developed to evaluate the top-down cracking behavior for asphalt pavement under Korean Army K-1 battle tank loads. In particular, the FE model developed includes “seam” along the crack length that allows the dual nodes at the same position and it creates two separate faces along the crack. Based on the analyses of stress distribution, it was found that higher magnitude of transverse tensile stress with depth occurred when crack is presented at the pavement surface. However, the existence of crack seems not have significant effect on transverse stress distribution for far away region. Also, it was identified that both longer crack length and greater stiffness gradient between the top and bottom of asphalt concrete (AC) layer are critical conditions for top-down cracking propagation. Based on the results analyzed, it was concluded that the FE model developed was able to provide reasonable and rational prediction in terms of the effect of the K-1 tank loads on characteristics for top-down cracking of asphalt pavement. In practice, the effect of these heavy loads can be potentially minimized by considering operation time to when the AC layer exhibits minimum daily temperature differential (e.g. from 9 am to 12 am as well as from 11 pm to 2 am). 본 연구는 유한요소해석법을 이용하여 한국군 K-1 전차 하중 하에서 아스팔트 포장의 Top-down cracking 거동 특성에 대하여 평가하였다. 특히, 아스팔트 포장의 균열 현상은 "Seam" 기법을 이용하여 모사하였다. 유한요소해석을 통해 얻어진 응력분포 분석결과에 의하면 포장 표면에 균열이 존재하는 경우 깊이에 따른 횡방향 인장응력이 크게 발생하였다. 그러나, 하중 영향권에서 멀리 떨어질수록 포장 표면의 균열 존재 여부가 횡방향 인장응력 분포에 미치는 영향은 매우 작았다. 반면, 균열의 길이와 아스팔트 표층의 상부와 하부 간 강성 분포도의 차이가 Top-down cracking 진행에 중대한 영향을 미치는 요소임이 밝혀졌다. 본 연구에서 개발된 유한요소해석 모델은 K-1 전차 하중 하에서 포장체의 Top-down cracking 거동 특성을 예측하는데 있어서 효과적으로 적용될 수 있을 것으로 판단하며, 실제로 포장체의 상부와 하부의 온도차에 따른 강성 분포도의 차이가 최소가 되는 시간대(즉 오전 9시~정오, 오후 11시~오전 2시)에 전차를 기동함으로써 아스팔트 포장의 파손을 최소화 할 수 있을 것으로 예상된다.

Finite Element Analysis to Simulate the Effect of Impact Rollers for Estimating the Influence Depth of Soil Compaction

김국주,천상현 대한토목학회 2016 KSCE JOURNAL OF CIVIL ENGINEERING Vol.20 No.7

The use of impact rollers has increased for many decades due to its diverse advantages. However, the current lack of theoretical verification and research-based technical guidelines that can effectively describe the effect of impact rollers is probably the greatest deficiency in our ability to accurately predict the benefits of deep compaction provided by impact compaction rollers. The 3-D Finite Element Analysis (FEA) was conducted using LS-DYNA to simulate the depth of influence for various impact rollers. Results indicated that the width of the contact area between the drum and the soil primarily controls the depth of compaction. The softer the soil is, the deeper the roller sinks in the soil. Also, the wider the contact area is, the deeper the compaction depth is. Thereby, the depth of compaction is highly dependent upon the stiffness of the soil. It was found that the surface pressure controls the degree of compaction and the surface pressure of the impact rollers is higher than that of the cylindrical rollers due to the dynamic effect. However, the distribution of the pressure is significantly variable for the impact rollers than the cylindrical rollers. It was concluded that the impact rollers seem to have more potential for use in final compaction of thicker layers.