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선사유적의 정비,복원(1) -구석기유적의 생태공원화 방안을 중심으로-
문석기 ( Seok Ki Moon ),장호수 ( Ho Su Jang ) 한국환경복원기술학회(구 한국환경복원녹화기술학회) 2011 한국환경복원기술학회지 Vol.14 No.4
This study is focused upon developing repairing and restoration methodologies of the Paleolithic sites. The Paleolithic era is not only the remote past, which ended ten thounds years ago, but the period of much different ecological condition compared with that of these days. There have been two kinds of conservation method adopted to restoration of Paleolithicsites which are historic park and ecological park. But there left not much historic remains than ecological sources in most Paleolithic sites, restoring them into ecological park is thought to be more reasonable for the purpose of conserving sites and remains. The first step of restoring Paleolithic sites is reconstructing environmental background in which they earned a living with their own life style at that time. There are three ways of ecological restoration for prehistoric sites, which are the reclamation, the rehabilitation, and the restoration. The reclamation requires physical modification, and the rehabilitation does biological modification, but only the restoration requires improved management. Among them, the most desirable way applicable upon the Paleolithic sites restitution is the reclamation.
알루미늄합금 6061-T6의 마찰교반용접 조건에 따른 기계적특성 및 용접부 조직평가
장석기(Seok-Ki Jang),박종식(Jong-Seek Park) 대한기계학회 2009 大韓機械學會論文集A Vol.33 No.7
This paper shows mechanical properties and behaviors of macro- and micro-structures on friction stir welded specimen with 6061-T6 aluminum alloy plate. It apparently results in defect-free weld zone jointed at welding conditions like the traverse speed of 267㎜/min, tool rotation speed of 2500rpm, pin inserted depth of 4.5㎜ and tilting angle of 2° with tool dimensions such as tool pin diameter of 5mm, shoulder diameter of 15㎜ and pin length of 4.5㎜. The tensile stress σT=228㎫ and the yield point σY=141㎫ are obtained at the condition of traverse speed of 267㎜/min and tool rotation speed of 2500rpm. With the constant rotation speed, the higher traverse speed become, the higher tensile stress and yielding point become. Vickers hardness for welding zone profile were also presented.
장석기 ( Seok Ki Jang ),이승준 ( Seung Jun Lee ),박재철 ( Jae Cheul Park ),김성종 ( Seong Jong Kim ) 한국부식방식학회(구 한국부식학회) 2015 Corrosion Science and Technology Vol.14 No.5
Corrosion is of greatest concern for metallic materials exposed to corrosive seawater or aggressive marine atmospheres.Marine structures and components made of metallic materials incur an initial cost and additional large costs for corrosion control and maintenance. There have been worldwide efforts to minimize marine corrosion and extend service life of the materials. It is believed that various factors are associated with corrosion of marine grade metallic materials, particularly the temperature of the solution affecting the corrosion rate by changing dissolved oxygen solubility and concentrations of chloride. In the present study, the electrochemical characteristics of S355ML steel are investigated to identify corrosion acceleration tendencies with changes in solution temperature under marine environments. It was found that increasing seawater temperature, promoted not only activation of chloride ion transfer,but also the formation of porous Fe(OH)3 or Fe2O3, leading to the acceleration of corrosion.
알카리 수용액에서 Mg-Al 합금의 양극산화시 전류밀도와 양극산화 시간의 효과
장석기,김성종,김정일,Jang Seok-Ki,Kim Seong-Jong,Kim Jeong-Il 한국마린엔지니어링학회 2005 한국마린엔지니어링학회지 Vol.29 No.1
The effects on the formation of anodic oxide films on Mg-Al alloy (AZ91) in 1M-NaOH solution was investigated using parameters of current density and time during anodizing The general tendency has been confirmed that the increase of anodizing time improves the corrosion resistance. It is considered that the formation of anodic oxide film was increased by increasing the applied current and the anodizing time to generate active dissolution reaction In anodizing at constant current density. passivity potentials shifted to noble direction with increasing current densities. It was confirmed that oxygen quantify in anodic oxide films increased with anodizing time. The compact films above 4 $mA/cm^2$ were formed with the shape of an island in grooves at early stage and then grew with combination of the islands
마찰교반용접한 5456-H116 알루미늄 합금 용접부 표면의 기계적 및 전기화학적 특성
장석기(Seok-Ki Jang),김성종(Seong-Jong Kim) 한국표면공학회 2008 한국표면공학회지 Vol.41 No.4
Small FRP (fiber-reinforced polymer) fishing ships have numerous problems with the point of the environmental and recycling perspectives. In light of these aspects, aluminum can be used as a material for ship building. It is environmental friendly, easy to recycle, and provides a high added value to fishing boats. In this paper, we report on mechanical and electrochemical characteristics of welding parts for friction stir welded 5456-H116 Al alloy. In friction stir welded at various traveling speeds under the rotation speed of 500 RPM, the best characteristics presented in traveling speed of 15㎜/min. The anodic polarizations of base metal and welding metal were observed tendency which current density from the open circuit potential suddenly increase. The cathodic polarization presented concentrated polarization caused by the dissolved oxygen reduction reaction and activation polarization caused by hydrogen generation. From result of Tafel analysis, the corrosion potential of 5456 alloy (Base metal) was lower than that of friction stir welded part, as were its corrosion current densities.
장석기,전정일,Jang Seok-Ki,Jeon Jeong-Il 한국마린엔지니어링학회 2006 한국마린엔지니어링학회지 Vol.30 No.1
This paper shows mechanical Properties and behaviors of macrostructures for specimens welded by F.S.W according to welding conditions and tool dimensions with $6.35mm_t$ aluminum 7075-T651 alloy plate. It apparently results in defect-free weld zone in case transition speed was changed to 15mm/min 61mm/min and 124mm/min under conditions of tool rotation speed such as 800rpm. 1250rpm and 1600rpm respectively with tool's Pin diameter 40mm and 60mm. The optimum mechanical property, ultimate stress,${\sigma}_Y=470Mpa$ is obtained at the condition of 124mm/min of travel speed with 800rpm of tool rotation speed using full screw type pin. shoulder dia. $20{\phi}mm$ pin dia. $6{\phi}mm$ and pin length 6mm. The full-screw type and the half-screw type pin shows the similar behaviors of weldability. It is found that the size of nugget is depended on tool transition speed and tool dimension by macrostructures of the cross section of weld zone.
마찰교반 용접법에 의한 맞대기 및 겹치기이음에 대한 용접부 거동의 비교연구
장석기(Seok Ki Jang),한민수(Min Su Han) 한국마린엔지니어링학회 2003 한국마린엔지니어링학회 학술대회 논문집 Vol.2003 No.-
The present paper is reported on comparison of properties such as hardness, ultimate strength, and explained behaviors of fracture for Butt and Lap jointed aluminum alloy sheet. The research in this experiment also shows the weldability of butt joint specimen is better than that of lap joint specimen using FSW with 2mml aluminum alloy sheet in milling machine.<br/> <br/>
5년간(’95~’99년)국내의 선원재해 현황에 관한 연구
장석기(Seok-Ki Jang),양원재(Weon-Jae Yang),박계각(Gyei-Kark Park),이창희(Chang-Hee Lee),남정길(Jeong-Gil Nam),천대일(Dae-Il Cheon) 한국항해항만학회 2002 한국항해항만학회지 Vol.26 No.3
최근 선원재해 감소를 위한 국내선사들의 많은 노력에도 불구하고 그 감소율은 둔감하고 있는 실정이며, 이에관한 일과성 유사연구 사례는 있으나 선원정책의 인적요소를 중심으로하는 본격적인 연구는 부족한 실정이다. 따라서, 본 연구에서는 현재 승선중이거나 승선경험이 있는 선원을 중심으로 설문조사를 실시하여 선원재해에 관한 의식현황을 분석하여 해상안전 및 선원재해에 관한 대비책을 제시하고자 한다. Recently, in the whole fields of industry including shipping business, the conception and importance of Human Factor is very highly and frequently emphasized. But the domestic crew disaster including injury and illness in our shipping business shows higher accident rate than other shipping countries. Therefore the developing of measures to prevent/reduce the accident is highly required as the marine accident including crew disaster causes enormous loss of property and human life in size and scale. But, because the domestic data regarding the crew accident are relatively insufficient and rare, the developing of those measures has many difficulties. Therefore, this study is to make the concerning data for the useful reference by showing the trend and current situation of crew accidents, assorted by the crew’s rank, type of the accident, injured part of the body, cause of the accident, type of ships and type of the works when the accident occurred, by using the each ocean-going shipping company’s recent 5 years(’95~’99) data in korea.
다양한 화성처리 용액 조건에서 마그네슘-알루미늄 합금위에 형성된 박막의 특성 평가
장석기,김성종,김정일,Jang Seok-Ki,Kim Seong-Jong,Kim Jeong-Il 한국마린엔지니어링학회 2005 한국마린엔지니어링학회지 Vol.29 No.1
The chemical conversion film formed on magnesium alloy was investigated by using the colloidal silica with some parameters such as solution pH. temperature, solution conditions, and treatment time. Moreover. the solutions consisted of colloidal silica titanium sulfate, and cobalt ions were used for the colloidal silica film to having a good corrosion resistance and adhesion properties. It was thought that the film at 298K was made with combination of Si-O. The quantity of film formed at high temperature such as 333K and 353K is smaller than dissolved quantity during chemical conversion treatment. Adding $CoSO_4$ to the colloidal silica solution enhanced the adhesion force between the silica film and magnesium substrate, The optimum conditions for the chemical conversion treatment solution were PH 2.90 s treatment, and 298K.
장석기(Seok Ki Jang),김성종(Seong Jong Kim),우용빈(Yong Bin Woo),박종식(Jong Seek Park) 한국마린엔지니어링학회 2009 한국마린엔지니어링학회 학술대회 논문집 Vol.2009 No.-
The joining of dissimilar aluminum 6061-T6 alloy to aluminum 5083-O alloy and vice versa was performed using friction stir welding technique. It apparently results in defect-free weld zone that traverse speed was changed to l24㎜/min under the tool rotation speed of 1250rpm and tilting angle of 2° with tool's pin diameter of 5㎜, the shoulder diameter of l5㎜ and the pin length of 4.5㎜.