후미등 중심점 추정을 이용한 V2V 광 카메라 통신 기반 군집주행 제어기술

진성윤(Sung Yooun Jin),최동녘(Dong Nyeok Choi),김병욱(Byung Wook Kim) 한국통신학회 2019 한국통신학회 학술대회논문집 Vol.2019 No.1

자율주행 플래투닝에서 V2V 광 카메라 통신기반 조향제어 기술

진성윤(Sung Yooun Jin),최동녘(Dong Nyeok Choi),김병욱(Byung Wook Kim) 한국통신학회 2018 한국통신학회 학술대회논문집 Vol.2018 No.6

Al-Ni 전구체의 연소합성 발포에 의한 Al₃Ni 폼과 할로우 파이프의 복합구조체 제작 및 폼의 충진성과 기공상태 조사

한창석,진성윤,권혁구,Han, Chang-Suk,Jin, Sung-Yooun,Kwon, Hyuk-Ku 한국재료학회 2019 한국재료학회지 Vol.29 No.10

In order to develop a process for manufacturing a composite structure of an intermetallic compound foam and a hollow material, the firing and pore form of the Al-Ni precursor in a steel pipe are investigated. When the Al-Ni precursor is foamed in a hollow pipe, if the temperature distribution inside the precursor is uneven, the pore shape distribution becomes uneven. In free foaming, no anisotropy is observed in the foaming direction and the pore shape is isotropic. However, in the hollow pipe, the pipe expands in the pipe axis direction and fills the pipe. The interfacial adhesion between $Al_3Ni$ foam and steel pipe is excellent, and interfacial pore and reaction layer are not observed by SEM. In free foaming, the porosity is 90 %, but it decreases to about 80 % in the foam in the pipe. In the pipe foaming, most of the pore shape appears elongated in the pipe direction in the vicinity of the pipe, and this tendency is more remarkable when the inside pipe diameter is small. It can be seen that the pore size of the foam sample in the pipe is larger than that of free foam, because coarse pores remain after solidification of the foam because the shape of the foam is supported by the pipe. The vertical/horizontal length ratio expands along the pipe axis direction by foaming in the pipe, and therefore circularity is reduced.

크롬 및 구리로 치환한 L1₂ Titanium Trialuminides합금의 고온변형거동

한창석,진성윤,방효인,Han, Chang-Suk,Jin, Sung-Yooun,Bang, Hyo-In 한국재료학회 2018 한국재료학회지 Vol.28 No.6

Crystal structure of the $L1_2$ type $(Al,X)_3Ti$ alloy (X = Cr,Cu) is analyzed by X-ray diffractometry and the nonuniform strain behavior at high temperature is investigated. The lattice constants for the $L1_2$ type $(Al,X)_3Ti$ alloys decrease in the order of the atomic number of the substituted atom X, and the hardness tends to increase. In a compressive test at around 473K for $Al_{67.5}Ti_{25}Cr_{7.5}$, $Al_{65}Ti_{25}Cr_{10}$ and $Al_{62.5}Ti_{25}Cu_{12.5}$ alloys, it is found that the stress-strain curves showed serration, and deformation rate dependence appeared. It is assumed that the generation of serration is due to dynamic strain aging caused by the diffusion of solute atoms. As a result, activation energy of 60-95 kJ/mol is obtained. This process does not require direct involvement. In order to investigate the generation of serrations in detail, compression tests are carried out under various conditions. As a result, in the strain rate range of this experiment, serration is found to occur after 470K at a certain critical strain. The critical strain increases as the strain rate increases at constant temperature, and the critical strain tends to decrease as temperature rises under constant strain rate. This tendency is common to all alloys produced. In the case of this alloy system, the serration at around 473K corresponds to the case in which the dislocation velocity is faster than the diffusion rate of interstitial solute atoms at low temperature.

크롬 및 구리로 치환한 L12 Titanium Trialuminides합금의 고온변형거동

한창석,진성윤,방효인 한국재료학회 2018 한국재료학회지 Vol.28 No.6

Crystal structure of the L12 type (Al,X)3Ti alloy (X = Cr,Cu) is analyzed by X-ray diffractometry and the nonuniform strain behavior at high temperature is investigated. The lattice constants for the L12 type (Al,X)3Ti alloys decrease in the order of the atomic number of the substituted atom X, and the hardness tends to increase. In a compressive test at around 473K for Al67.5Ti25Cr7.5, Al65Ti25Cr10 and Al62.5Ti25Cu12.5 alloys, it is found that the stress-strain curves showed serration, and deformation rate dependence appeared. It is assumed that the generation of serration is due to dynamic strain aging caused by the diffusion of solute atoms. As a result, activation energy of 60-95 kJ/mol is obtained. This process does not require direct involvement. In order to investigate the generation of serrations in detail, compression tests are carried out under various conditions. As a result, in the strain rate range of this experiment, serration is found to occur after 470K at a certain critical strain. The critical strain increases as the strain rate increases at constant temperature, and the critical strain tends to decrease as temperature rises under constant strain rate. This tendency is common to all alloys produced. In the case of this alloy system, the serration at around 473K corresponds to the case in which the dislocation velocity is faster than the diffusion rate of interstitial solute atoms at low temperature.

반응성 스프레이방법으로 제작한 티타늄 알루미나이드/탄화물 복합박막의 미세조직과 경도

한창석,진성윤,Han, Chang-Suk,Jin, Sung-Yooun 한국재료학회 2020 한국재료학회지 Vol.30 No.7

A variety of composite powders having different aluminum and carbon contents are prepared using various organic solvents having different amounts of carbon atoms in unit volume as ball milling agents for titanium and aluminum ball milling. The effects of substrate temperature and post-heat treatment on the texture and hardness of the coating are investigated by spraying with this reduced pressure plasma spray. The aluminum part of the composite powder evaporates during spraying, so that the film aluminum content is 30.9 mass%~37.4 mass% and the carbon content is 0.64 mass%~1.69 mass%. The main constituent phase of the coating formed on the water-cooled substrate is a non-planar α₂ phase, obtained by supersaturated carbon regardless of the alloy composition. When these films are heat-treated at 1123 K, the main constituent phase becomes γ phase, and fine Ti₂AlC precipitates to increase the film hardness. However, when heat treatment is performed at a higher temperature, the hardness is lowered. The main constitutional phase of the coating formed on the preheated substrate is an equilibrium gamma phase, and fine Ti₂AlC precipitates. The hardness of this coating is much higher than the hardness of the coating in the sprayed state formed on the water-cooled substrate. When hot pressing is applied to the coating, the porosity decreases but hardness also decreases because Ti₂AlC grows. The amount of Ti₂AlC in the hot-pressed film is 4.9 vol% to 15.3 vol%, depending on the carbon content of the film.

분말야금법으로 제작한 NiAl합금의 기계적성질 및 형상기억특성

한창석,진성윤,권혁구,Han, Chang-Suk,Jin, Sung-Yooun,Kwon, Hyuk-Ku 한국재료학회 2020 한국재료학회지 Vol.30 No.5

The composition of martensite transformation in NiAl alloy is determined using pure nickel and aluminum powder by vacuum hot press powder metallurgy, which is a composition of martensitic transformation, and the characteristics of martensitic transformation and microstructure of sintered NiAl alloys are investigated. The produced sintered alloys are presintered and hot pressed in vacuum; after homogenizing heat treatment at 1,273 K for 86.4 ks, they are water-cooled to produce NiAl sintered alloys having relative density of 99 % or more. As a result of observations of the microstructure of the sintered NiAl alloy specimens quenched in ice water after homogenization treatment at 1,273 K, it is found that specimens of all compositions consisted of two phases and voids. In addition, it is found that martensite transformation did not occur because surface fluctuation shapes did not appear inside the crystal grains with quenching at 1,273 K. As a result of examining the relationship between the density and composition after martensitic transformation of the sintered alloys, the density after transformation is found to have increased by about 1 % compared to before the transformation. As a result of examining the relationship between the hardness (Hv) at room temperature and the composition of the matrix phase and the martensite phase, the hardness of the martensite phase is found to be smaller than that of the matrix phase. As a result of examining the relationship between the temperature at which the shape recovery is completed by heating and the composition, the shape recovery temperature is found to decrease almost linearly as the Al concentration increases, and the gradient is about -160 K/at% Al. After quenching the sintered NiAl alloys of the 37 at%Al into martensite, specimens fractured by three-point bending at room temperature are observed by SEM and, as a result, some grain boundary fractures are observed on the fracture surface, and mainly intergranular cleavage fractures.

비정질상인 Ti₅Si₃ MA분말의 가압소결 동안 소결체의 치밀화 촉진현상 요인에 대한 조사

한창석,진성윤,권혁구,Han, Chang-Suk,Jin, Sung-Yooun,Kwon, Hyuk-Ku 한국재료학회 2020 한국재료학회지 Vol.30 No.6

In this study, factors considered to be causes of promotion of densification of sintered pellets identified during phase change are reviewed. As a result, conclusions shown below are obtained for each factor. In order for MA powder to soften, a temperature of 1,000 K or higher is required. In order to confirm the temporary increase in density throughout the sintered pellet, the temperature rise due to heat during phase change was found not to have a significant effect. While examining the thermal expansion using the compressed powder, which stopped densification at a temperature below the MA powder itself, and the phase change temperature, no shrinkage phenomenon contributing to the promotion of densification is observed. The two types of powder made of Ti-silicide through heat treatment are densified only in the high temperature region of 1,000 K or more; it can be estimated that this is the effect of fine grain superplasticity. In the densification of the amorphous powder, the dependence of sintering pressure and the rate of temperature increase are shown. It is thought that the specific densification behavior identified during the phase change of the Ti-37.5 mol.%Si composition MA powder reviewed in this study is the result of the acceleration of the powder deformation by the phase change from non-equilibrium phase to equilibrium phase.

Effect of Mo and Mn Addition on the Oxidation Behavior of Binary Ti-Al Alloys

한창석,진성윤,방효인 한국재료학회 2018 한국재료학회지 Vol.28 No.6

Binary Ti-Al alloys below 51.0 mass%Al content exhibit a breakaway, transferring from parabolic to linear rate law. The second Al2O3 layer might have some protectiveness before breakaway. Ti-63.1 mass%Al oxidized at 1173 K under parabolic law. Breakaway oxidation is observed in every alloy, except for Ti-63.1 mass%Al. After breakaway, oxidation rates of the binary TiAl alloys below 34.5 mass%Al obey almost linear kinetics. The corrosion rate of Ti-63.1 mass%Al appears to be almost parabolic. As content greater than 63.0 mass% is found to be necessary to form a protective alumina film. Addition of Mo improves the oxidation resistance dramatically. No breakaway is observed at 1123 K, and breakaway is delayed by Mo addition at 1173 K. At 1123 K, no breakaway, but a parabolic increase in mass gain, are observed in the Mo-added TiAl alloys. The binary Ti-34.5 mass%Al exhibits a transfer from parabolic to linear kinetics. At 1173 K, the binary alloys show vary fast linear oxidation and even the Mo-added alloys exhibit breakaway oxidation. The 2.0 mass%Mo-added TiAl exhibits a slope between linear and parabolic. At values of 4.0 and 6.0 mass% added TiAl alloys, slightly larger rates are observed than those for the parabolic rate law, even after breakaway. On those alloys, the second Al2O3 layer appears to be persistently continuous. Oxidation resistance is considerably degraded by the addition of Mn. Mn appears to have the effect of breaking the continuity of the second Al2O3 layer.

그림자효과를 이용하여 증착한 타이타늄 박막의 미세구조 및 형상

한창석,진성윤,권혁구,Han, Chang-Suk,Jin, Sung-Yooun,Kwon, Hyuk-Ku 한국재료학회 2019 한국재료학회지 Vol.29 No.11

In order to observe the microstructure and morphology of porous titanium -oxide thin film, deposition is performed under a higher Ar gas pressure than is used in the general titanium thin film production method. Black titanium thin film is deposited on stainless steel wire and Cu thin plate at a pressure of about 12 Pa, but lustrous thin film is deposited at lower pressure. The black titanium thin film has a larger apparent thickness than that of the glossy thin film. As a result of scanning electron microscope observation, it is seen that the black thin film has an extremely porous structure and consists of a separated column with periodic step differences on the sides. In this configuration, due to the shadowing effect, the nuclei formed on the substrate periodically grow to form a step. The surface area of the black thin film on the Cu thin plate changes with the bias potential. It has been found that the bias of the small negative is effective in increasing the surface area of the black titanium thin film. These results suggest that porous titanium-oxide thin film can be fabricated by applying the appropriate oxidation process to black titanium thin film composed of separated columns.