단조용 환봉이 유도가열실험 및 이론 해석에 관한 연구

최진호,이원재,강성욱,주성호,조봉환,김병화 대한금속재료학회(대한금속학회) 1999 대한금속·재료학회지 Vol.37 No.12

A solid type crankshaft, one of the most important part of medium size marine engine, is manufactured by forging method. The induction heating system(600 ㎾ = 100%, 190∼200 ㎐) is used to heat rounded bar(Ø285 ㎜) up to 1200℃ for the forging. Numerical analysis was performed on the heating process at various operating conditions by applying boundary conditions based on theoretical approach. Experiments were also performed on the same type of mended bar to confirm the simulation results. Experimental results showed that the induction heating phenomena were effected by the phase transformation at A_(c₁) A_(c₃) temperature range, the magnetic transformation at A₂ (curie point) temperature range and the mass effect of large volume of rounded bar. At the 62% power, our induction heating system showed the maximum efficiency and the heating time was about 40∼50 minutes.

HNO3 : H2O2 : HF 세척법을 이용한 실리콘 직접 접합 기술에 관한 특성 연구

이종석,성만영,최우범,주철민,이정훈 고려대학교 공학기술연구소 1999 공학논문집 Vol.37 No.1

We have studied the method of silicon direct bonding using the mixture of HNO₃, H₂O₂ and HF chemicals called the controlled slight etch (CSE) solution for the effective wafer cleaning. CSE, two combinations of oxidizing and etching agents, have been used to clean the silicon surfaces prior to wafer bonding. Two wafers of silicon and silicon dioxide were contacted each other at room temperature and post-annealed at 300∼1100℃ in N₂ ambient for 2.5 hour. We have cleaned silicon wafers with the various HF concentrations and characterized the parameters with regard to surface roughness, chemical nature, chemical oxide thickness, and bonding energy. It was observed that the chemical oxide thickness of the silicon wafer decreased with increasing HF concentrations. The initial interfacial energy and final energy post-annealed at 1100℃ for 2.5 hour measured by the crack propagation method was 122 mJ/㎡ and 2.96 J/㎡ , respectively.

5083 Al 합금 용접재의 조직 및 저온 인장성질에 미치는 시효처리의 영향

성장현,이해우,주동원,이준희,이태청 한국열처리공학회 2000 熱處理工學會誌 Vol.13 No.1

The microstructural characteristics and low temperature tensile properties between 25℃ and -196℃ for as-welded and age hardened specimen by using Al 5083-H321 for base metal, 5083-5356 and 5083-4043 weldments have been investigated. The hardness of 5083-5356 weldment decreases with aging treatment, whereas the weld region of 5083-4043 weldment shows remarkable increase in hardness after aging due to the precipitation of fine Si particle at the grain boundaries and interiors. Low temperature tensile properties of 5083 Al base metal, 5083-5356 and 5083-4043 weldments appear to be the increment of tensile strengths and elongations at the room temperature and -196℃, while the decrement of tensile properties around -50℃ is shown. Through the observation of fine serration to fracture in the stress-strain curve and tensile fractography, the increment of localized deformation leading to promote the neck initiation and the increment of the dimple size cause to decrease in tensile strengths and elongations around -50℃. For the tensile specimen of the 5083 base metal, 5083-5356 and 5083-4043 weldments, the reason to increase in elongation after solution and aging treatment is the diminishment of fine pit, the resolution of Mg into the matrix and the spheridization of the eutectic Si.

Al 함유 13%Cr 스테인리스강의 표면 질소침투 열처리에 미치는 첨가원소 탄소의 영향 : 13%Cr 스테인리스강의 고질소 표면침투 열처리

성장현,주동원,김기돈,유대경,박진욱 한국열처리공학회 2000 熱處理工學會誌 Vol.13 No.3

This study aims to investigate the effect of carbon content on the surface nitrogen permeation of 13%Cr-1.8%Al alloyed stainless steels. The surface nitrogen permeation was performed at 1050℃-1200℃ in the 1㎏/㎠ nitrogen gas atmosphere. The nitrogen permeated surface layer of the specimen containing 0.03%C consists of AlN, martensite and retained austenite phases, while the surface layer of the specimen containing 0.14%C appears the AlFe₃C_x phase including former three phases. The specimen containing 0.14%C shows lower total case depth than that containing 0.03%C at the nitrogen permeation temperatures of 1050℃ and 1100℃, while the total case depth of the specimen containing 0.14%C is remarkably increased at the temperature of 1150℃ and 1200℃ due to the increase in the retained austenite content. Martensitic phase, AlN and AlFe₃C_x precipitate of the nitrogen permeated surface layer cause to increase the surface hardness of 550∼600Hv.

Magnetic Properties of <tex> $ [\hbox{Ni}_{97{\rm at.}\%}$</tex>-W<tex> $_{3{\rm at.}\%}]_{{100}-{x}}$</tex>-Cu<tex> $_x$</tex> Textured Substrates for Coated Conductors

Song, K.J.,Ko, R.K.,Kim, H.S.,Ha, H.S.,Ha, D.W.,Oh, S.S.,Park, C.,Yoo, S.-I.,Kim, M.W.,Kim, C.J.,Joo, J.H. Institute of Electrical and Electronics Engineers 2007 IEEE transactions on applied superconductivity Vol.17 No.2

<P>The degree of ferromagnetism of Ni-W<SUB>y</SUB> alloys decreases as W-content y increases. Both the saturation magnetization <I>M</I> <SUB>sat</SUB> and Curie temperature <I>T</I> <SUB>c</SUB> decrease linearly with W-content y, and both <I>M</I> <SUB>sat</SUB> and <I>T</I> <SUB>c</SUB> go to zero at critical concentration of y<SUB>c</SUB> ~9.50 at.% W. To compare with Ni-W alloys, the magnetic properties of a series of both as-rolled (non-textured) and annealed (biaxially textured) [Ni<SUB>97at.%</SUB>-W<SUB>3at.%</SUB>]<SUB>100-x</SUB>-Cu<SUB>x</SUB> alloy tapes with compositions x = 0, 1, 3, 5, and 7 at.%, were studied. Characterization methods included XRD analyses to investigate the biaxial texturing of the annealed [Ni-W]-Cu alloy tapes and studies of the magnetization for both as-rolled and annealed [Ni-W]-Cu alloy tapes. Both the isothermal mass magnetizations <I>M</I>(<I>H</I>) of a series of samples at different fixed temperatures and <I>M</I>(<I>T</I>) in fixed field, were measured. The effect of Cu addition on both the saturation magnetization and Curie temperature T<SUB>c</SUB> of the Ni<SUB>97at.%</SUB>-W<SUB>3at.%</SUB> alloy was investigated.</P>

O₂/SF₆/CH₄ 플라즈마를 이용한 플렉시블 Polycarbonate와 PMMA의 건식 식각

주영우(Y. W. Joo),박연현(Y. H. Park),노호섭(H. S. Noh),김재권(J. K. Kim),이제원(J. W. Lee) 한국진공학회(ASCT) 2009 Applied Science and Convergence Technology Vol.18 No.2

현재 플렉시블 폴리머를 이용한 MEMS (Microelectromechanical Systems) 기술이 빠르게 발전하고 있다. 그 중에서 Polycarbonate (PC), Poly Methyl Methacrylate (PMMA)와 같은 플렉시블 폴리머 재료는 광학적 특성이 우수하고 인체 친화적이며 미세 패턴 제조 공정이 용이하다는 등의 많은 장점을 가지고 있다. 본 연구는 반응성 이온 식각 기술을 이용하여 O₂, SF? 그리고 CH₄의 삼성분계 가스의 혼합 비율에 따른 PC와 PMMA의 건식 식각 결과 및 특성 평가에 관한 것이다. 준비한 각각의 기판에 포토리소그래피 방법으로 마스크를 형성하여 샘플을 만들었다. RF 척 파워를 100 W, 총 가스 유량을 10 sccm으로 고정시켜 플라즈마 식각 실험을 실시하였다. 그 결과에 의하면 전체적으로 PMMA의 식각율이 PC보다는 약 2배 정도 높았다. 그 결과는 PC는 PMMA 보다 상대적으로 높은 녹는점을 가지고 있다는 사실과 관계가 있다고 생각한다. 또한 O²/SF?/CH₄의 삼성분계 가스와 SF?/CH₄, O₂/SF?, O₂/CH₄로 나누었을 때 O₂/SF?의 혼합 가스에서 PMMA와 PC의 식각 속도가 가장 높았다 (PC: 5 sccm O₂/5 sccm SF6에서 약 350 nm/min, PMMA: 2.5 sccm O₂/7.5 sccm SF6에서 약 570 ㎚/min). SEM을 활용하여 식각된 표면을 분석한 결과 PC는 PMMA보다 상대적으로 식각 표면이 더 매끈하였다. 또한 표면 거칠기 분석결과 PC의 표면 거칠기는 1.9~3.88 ㎚이었지만 PMMA의 표면 거칠기는 17.3~26.1 ㎚로 현저하게 높았음을 확인할 수 있었다. There has been a rapid progress for flexible polymer-based MEMS(Microelectromechanical Systems) technology. Polycarbonate (PC) and Poly Methyl Methacrylate (PMMA), so-called acrylic, have many advantages for optical, non-toxic and micro-device application. We studied dry etching of PC and PMMA as a function of % gas ratio in the O₂/SF?/CH₄ ternary plasma. A photoresist pattern was defined on the polymer samples with a mask using a conventional lithography. Plasma etching was done at 100 W RIE chuck power and 10 sccm total gas flow rate. The etch rates of PMMA were typically 2 times higher than those of PC in the whole experimental range. The result would be related to higher melting point of PC compared to that of PMMA. The highest etch rates of PMMA and PC were found in the O₂/SF? discharges among O₂/SF?, O₂/CH₄ and SF6/CH4 and O₂/SF?/CH₄ plasma composition (PC: ~350 ㎚/min at 5 sccm O₂/5 sccm SF?, PMMA: ~570 nm/min at 2.5 sccm O₂/7.5 sccm SF6). PC has smoother surface morphology than PMMA after etching in the O₂/SF?/CH₄ discharges. The surface roughness of PC was in the range of 1.9~3.88 ㎚. However, that of PMMA was 17.3~26.1 ㎚.

O₂/SF₆, O₂/N₂와 O₂/CH₄ 플라즈마를 이용한 폴리카보네이트 건식 식각

주영우(Y.W. Joo),박연현(Y. H. Park),노호섭(H.S. Noh),김재권(J. K. Kim),이성현(S.H. Lee),조관식(G. S. Cho),송한정(H. J. Song),전민현(M. H. Jeon),이제원(J. W. Lee) 한국진공학회(ASCT) 2008 Applied Science and Convergence Technology Vol.17 No.1

O₂/SF?, O₂/N₂ 그리고 O₂/CH₄의 혼합 가스를 이용하여 폴리카보네이트의 플라즈마 식각을 연구하였다. 플라즈마 식각 장비는 축전 결합형 플라즈마 시스템을 사용하였다. 폴리카보네이트 식각은 감광제 도포 후에 UV 조사의 포토리소그래피 방법으로 마스크를 제작하여 실험하였다. 본 식각 실험에서는 O₂와 다른 기체와의 혼합비와 RIE 척 파워 증가에 따른 폴리카보네이트의 식각 특성 연구를 중심으로 하였다. 특히 건식 식각 시에 사용한 공정 압력은 100 mTorr로 유지하였으며 공정 압력은 기계적 펌프만을 사용하여 유지하였다. 식각 실험 후에 표면 단차 측정기, 원자력간 현미경 그리고 전자 현미경 등을 이용하여 식각한 샘플을 분석하였다. 실험 결과에 의하면 폴리카보네이트 식각에서 O₂/SF?의 혼합 가스를 사용하면 순수한 O₂나 SF?를 사용한 것보다 각각 약 140 % 와 280 % 정도의 높은 식각 속도를 얻을 수 있었다. 즉, 100 W RIE 척 파워와 100 mTorr 공정 압력을 유지하면서 20 sccm O₂의 플라즈마 식각에서는 약 0.4 ㎛/min, 20 sccm의 SF?를 사용하였을 때에는 약 0.2 ㎛/min의 식각 속도를 얻었다. 그러나 60 %의 O₂와 40 %의 SF?로 혼합된 플라즈마 분위기에서는 20 sccm의 순수한 O₂에 비해 상대적으로 낮은 -DC 바이어스가 인가되었음에도 식각 속도가 약 0.56 ㎛/min으로 증가하였다. 그러나 SF? 양의 추가적인 증가는 폴리카보네이트의 식각 속도를 감소시켰다. O₂/N₂와 O₂/CH₄의 플라즈마 식각에서는 N₂와 CH₄의 양이 각각 증가함에 따라 식각 속도가 감소하였다. 즉, O₂에 N₂와 CH₄의 혼합은 폴리카보네이트의 식각 속도를 저하시켰다. 식각된 폴리카보네이트의 표면 거칠기 절대값은 식각 전에 비해 2 ~ 3 배정도 증가하였지만 전자현미경으로 표면을 관찰 하였을 때에는 식각 실험 후의 폴리카보네이트의 표면이 깨끗한 것을 확인할 수 있었다. RIE 척 파워의 증가는 -DC 바이어스와 폴리카보네이트의 식각 속도를 거의 선형적으로 증가시켰으며 이 때 폴리카보네이트의 감광제에 대한 식각 선택비는 약 1:1 정도였다. 본 연구의 의미는 기계적 펌핑 시스템만을 사용한 간단한 플라즈마 식각 시스템으로도 O₂/SF?의 혼합 가스를 사용하면 폴리카보네이트의 미세 구조를 만드는데 사용이 가능하며 O₂/N₂ 와 O₂/CH₄의 결과에 비해 상대적으로 우수한 식각 조건을 얻을 수 있었다는 것이다. 이 결과는 다른 폴리머 소재 미세 가공에도 응용이 가능하여 앞으로 많이 사용될 수 있을 것으로 예상한다. We studied plasma etching of polycarbonate in O₂/SF?, O₂/N₂ and O₂/CH₄. A capacitively coupled plasma system was employed for the research. For patterning, we used a photolithography method with UV exposure after coating a photoresist on the polycarbonate. Main variables in the experiment were the mixing ratio of O₂ and other gases, and RF chuck power. Especially, we used only a mechanical pump for in order to operate the system. The chamber pressure was fixed at 100 mTorr. All of surface profilometry, atomic force microscopy and scanning electron microscopy were used for characterization of the etched polycarbonate samples. According to the results, O₂/SF? plasmas gave the higher etch rate of the polycarbonate than pure O₂ and SF? plasmas. For example, with maintaining 100W RF chuck power and 100 mTorr chamber pressure, 20 sccm O₂ plasma provided about 0.4 ㎛/min of polycarbonate etch rate and 20 sccm SF? produced only 0.2 ㎛/min. However, the mixed plasma of 60 % O₂ and 40 % SF? gas flow rate generated about 0.56 ㎛ with even low -DC bias induced compared to that of O₂. More addition of SF? to the mixture reduced etch of polycarbonate. The surface roughness of etched polycarbonate was roughed about 3 times worse measured by atomic force microscopy. However examination with scanning electron microscopy indicated that the surface was comparable to that of photoresist. Increase of RF chuck power raised -DC bias on the chuck and etch rate of polycarbonate almost linearly. The etch selectivity of polycarbonate to photoresist was about 1:1. The meaning of these results was that the simple capacitively coupled plasma system can be used to make a microstructure on polymer with O₂/SF? plasmas. This result can be applied to plasma processing of other polymers.

Magnetism in Ni-W textured substrates for coated conductors

Song K. J.,Park Y. M.,Yang J. S.,Kim S. W.,Ko R. K.,Kim H. S.,Ha H. S,Oh S. S.,Park C.,Joo J. H.,Kim C. J. The Korea Institute of Applied Superconductivity a 2005 한국초전도저온공학회논문지 Vol.7 No.2

The magnetic properties of a series of both annealed (biaxially textured) and as-rolled (non-textured) Ni-xW alloy tapes with compositions x = 0,1,3, and 5 at.$\%$, were studied. Characterization methods included XRD analyses to investigate the biaxial cube texturing of the annealed Ni-W alloy tapes and studies of the magnetization M for both annealed and as-rolled Ni-W alloy tapes. Both the isothermal mass magnetizations M(H) of a series of samples at different fixed temperatures and M(T) in fixed field, employing a PPMS-9 (Quantum Design), were measured. The Ni-W alloys have shown much reduced ferromagnetism as W-content x increases. Both the saturation magnetization Msat and Curie temperature Tc decrease linearly with W-content x, and both Msat and Tc go to zero at critical concentration of Xc - 9.50 at. $\%$ W.

예열기간중 엔진 실린더 라이너에 대한 비정상 열전달 해석

주원석(W.S.Joo),정인곤(I.G.Jung),박정규(J.K.Park),이재순(J.S.Lee) 한국자동차공학회 1998 한국자동차공학회 춘 추계 학술대회 논문집 Vol.1998 No.5_1

In this study, a two-dimension finite-difference model was developed to predict the temperature distribution of chamber at preheating process. The study consists of a mathematical modeling for the unsteady heat transfer in the cylinder. The temperature distribution of liner for diesel engine was analyzed and measured. The purpose of this study is to analyze temperature distribution of liner by the finite-difference method and to measure temperature distribution for each points.<br/>

비대칭 다이어프램 밸브의 설계 해석

신민철(M. C. Shin),이상욱(S.W. Lee),주영철(Y. C. Joo),이광현(K. H. Lee),신승우(S. W. Shin),이종화(J. H. Lee) 한국정밀공학회 2014 한국정밀공학회 학술발표대회 논문집 Vol.2014 No.10월