• Polymer(Korea)
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• v.37 no.4
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• pp.547-552
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• 2013

Polyimide (PI) containing carboxyl functional group was prepared and reacted with diaminosiloxane during high temperature film casting. The morphology of resulting film was observed by using transmission electron microscopy (TEM) and energy dispersive X-ray spectroscopy (EDX), which revealed that globular 100 nm-sized PI domains and continuous polysiloxane phase were formed. X-ray photoelectron spectroscopy (XPS) study indicated that air-film interface mainly consisted of polysiloxane blocks. Poly(imidesiloxane) thin layer was thermostable until $400^{\circ}C$ and its pressure- sensitive adhesive property was retained up to $300^{\circ}C$. The comparative experiments revealed that grafting between carboxyl groups of polyimide and aminosiloxane was crucial for formation of microdomain structure and pressure-sensitive adhesive property.

• Analytical Science and Technology
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• v.21 no.2
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• pp.117-122
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• 2008

Dual scintillator for simultaneous alpha- and beta-ray counting used by detection materials of a surface contamination monitor was developed. In this study, preparation method was not a heat melting method but a solvent method, by which the counting material was manufactured by dissolving the polymer materials with solvent. It was simplified the preparation process. Plastic scintillator for beta-ray counting was prepared by solidifying the casting solution mixed with organic scintillator, polymer, and solvent. ZnS(Ag) scintillator layer was prepared by screen printing the paste solution mixed with ZnS(Ag), paste, and solvent onto the plastic layer. The good counting ability for alpha- and beta-ray using the ZnS(Ag)/plastic dual scintillator prepared and possibility for the counting material of surface contamination monitor was confirmed.

• Advances in materials Research
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• v.2 no.1
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• pp.37-49
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• 2013

The transition metal salt doped solid polymer electrolyte [TSPE] were prepared with HPMC as a host polymer. The virgin and doped films were prepared by solution-casting method and investigated using wide angle X-ray scattering method. Micro structural parameters like lattice strain (g%), stacking/twin faults, the average number of unit cells counted in a direction perpendicular to the Bragg's plane (hkl) spacing of (hkl) planes dhkl, crystallite size Ds, distortion width, standard deviation were determined by whole pattern powder fitting (WPPF) method, which is an extension of single order method. It is found that the crystallite size decreases with the increase in the content of $FeCl_3$. This decrease is due to increase in localized breaking of polymer network which also accounts for the amorphous nature of the material. The filler inorganic salt $FeCl_3$ acts as plasticizer. FTIR study also confirms and justifies the interaction between the polymer and in-organic salt in the matrix. Physical properties like mechanical stability and Ac conductivity in these films are in conformity with the X-ray results.

• Journal of Korea Foundry Society
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• v.34 no.1
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• pp.1-5
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• 2014

The austempering transformation behavior in Fe-0.7wt.%C-2.3wt.%Si-0.3wt.%Mn steel is investigated. Each specimen was austenitized for 60 min at $900^{\circ}C$, and austempered at $380^{\circ}C$ for different time periods varying from 2 min to 256 min. After the austempering heat treatment, the Stage I and II evolutions are performed using optical metallography, X-ray diffraction and image analyses. Variations in the X-ray diffraction patterns and lattice parameters of the ferrite and austenite demonstrate that the residual austenite decomposes into ferrite and carbide during the Stage II evolution; moreover the amount of ferrite increases during the Stage I evolution. While the amount of austenite increases during Stage I, it dicreases during Stage II. Overall, the variations in the volume fractions of the microstructure and carbide formation in stages I and II meet high temperature austempering reaction of the ausferrite microstructure.

• KOREAN JOURNAL OF PACKAGING SCIENCE & TECHNOLOGY
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• v.27 no.2
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• pp.85-90
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• 2021

The gamma irradiation was on to Poly(butylene sebacate-co-terephthalate) (PBSeT), Poly(butylene adipate-co-terephthalate) (PBAT), Poly(lactic acid) (PLA) and casting polypropylene (CPP) at dose levels from 0 to 50 kGy. The properties of gamma irradiated samples were analyzed using DSC, TGA, UTM and FT-IR spectra. The mechanical and thermal properties of PBSeT and PBAT after gamma irradiation were less affected than CPP. The tensile strength and elongation of PBSeT was not affected by gamma irradiation, while these of PBAT, PLA and CPP were significantly decreased at 50 kGy gamma-ray dose. The thermal stability of PBSeT, PBAT, PLA and CPP showed a similar tendency to tensile strength. The glass transition temperature(T_g) and melting temperature(T_m) of PBSeT and PBAT were not altered by increasing gamma-ray dose, while these of PLA and CPP decreased. The chemical composition of all samples was not modified by gamma irradiation, and it was confirmed by FT-IR spectra. Based on mechanical and thermal stability studies of gamma irradiation on bioplastics, tested biodegradable packaging materials showed a potential to be used in sterilization process up to 35 kGy.

• Journal of the Korea Society for Simulation
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• v.16 no.3
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• pp.57-63
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• 2007

In real time rendering of fetus the empty space leaping while traversing a ray is most frequently used accelerating technique. The main idea is to skip empty voxel samples which do not contribute the result image and it speeds up the rendering time by avoiding sampling data while traversing a ray in the empty region, saving a substantial number of interpolations. Calculating the distance from the nearest object boundary for every yokel can reduce the sampling operation. Among widely-well-known distance maps, those estimates the true distance, such as euclidean distance, takes a long time to compute because of the complicated floating-point operations, and others which uses approximated distance functions, such as city-block and chessboard, provides faster computation time but sampling error may can occur. In this paper, therefore, we analyze the characteristics of several distance maps and compare the number of samples and rendering time. And we aim to suggest the most appropriate distance map for rendering of fetus in ultrasound image.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2007.05a
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• pp.123-126
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• 2007

Deformation behavior of $Zr_{55}Cu_{30}Al_{10}Ni_5$ (at. %) bulk metallic glass (BMG) fabricated by suction casting method has been investigated at elevated temperatures in this study. The BMG was first verified to have an amorphous structure thru X-ray diffraction (XRD) and differential scanning calorimetry (DSC). A series of compression tests has consequently been performed in supercooled liquid temperature region to investigate the high temperature deformation behavior. A transition from Newtonian to non-Newtonian flow appeared to take place depending upon both the strain rate and test temperature. A processing map based on a dynamic materials model has been constructed to estimate a feasible forming condition for this BMG alloy.

• Proceedings of the IEEK Conference
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• 2001.09a
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• pp.899-902
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• 2001

최근에 3 차원 가상 내시경은 환자에게 고통을 주지않고 내부 기관을 볼 수 있는 대체 방법으로 주목을 받고 있다. 인터랙티브(interacticve)한 렌더링 속도로 기관의 내부 표면을 도시하기 위해 표면 렌더링이 사용될 수 있지만, 이는 사실적인 렌더링 화질을 얻기에 부적합하고, 병변의 자세한 구조를 표현하기에 적합하지 않으며, 표면 뒤편의 조직을 도시할 수 없다. 이러한 이유로 볼륨 렌더링이 표면 렌더링의 대안으로 사용될 수 있지만 많은 계산량을 필요로 하므로, 대부분의 볼륨 렌더링 기반의 가상 내시경 시스템들은 부가적인 하드웨어나 큰 용량의 메모리를 사용한다. 본 논문은 가상 내시경을 위해 원근 레이 캐스팅 (perspective ray casting)을 이용한 볼륨 렌더링 기법의 고속화에 그 목적이 있다. 렌더링 속도를 높이기 위해서 서브샘플링(sub-sampling)된 화소들에 대해 레이 캐스팅을 수행하고, 이 과정에서 동시에 깊이 정보를 얻는다. 얻어진 깊이 정도로부터 남아있는 화소들에 대한 깊이 정보를 예측함으로써. 이를 레이 캐스팅의 속도 향상에 이용한다. 제안한 알고리즘을 이용하여 기존의 방법에 비해 기관지 내시경에서 77%, 대장 내시경에서 85%까지 렌더링 시간을 줄일 수 있고, 따라서 인터랙티브 렌더링이 가능하다.

• Proceedings of the Korean Information Science Society Conference
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• 2003.04c
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• pp.211-213
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• 2003

이 논문에서는 레이캐스팅을 고속화하는 단순하고 효율적인 알고리즘을 제안한다. 범용 PC에서 볼륨데이터를 이용하여 애니메이션을 하기 위해서는 초당 30 프레임의 영상을 생성하여야하나 아직 이에 도달하지 못하여 고속화가 필요하다. 지금까지의 바운딩서피스 기반의 레이캐스팅의 고속화에서는 임의의 시점에서 객체(object)의 깊이(depth)값을 그 객체의 바운딩서피스를 깊이 버퍼에 투영하여 구하였다. 이와는 다르게 이 논문에서 제안하는 방법은 시점과 무관하게 x, y, z 세 방향의 깊이 버퍼를 설치하고 이 것을 이용하여 임의의 방향에서 시정에 대한 물체의 깊이 값을 구한다. 이렇게 함으로서 임의의 시점에서 객체의 깊이 값을 구하는 시간을 N$^3$에서 8$N_2$으로 줄일 수 있다. 여기서 N은 차원당 복셀의 개수이다.

• Journal of the Korea Computer Graphics Society
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• v.23 no.3
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• pp.47-54
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• 2017

In this paper, we propose an improved curvature-based GPU (Graphics Processing Unit) isosurface ray-casting technique. Our method adopts the fast evaluation method proposed by Sigg et al. [1] to find the isosurface, but replaces the computation of the gradient and Hessian with the de Boor algorithm. In this way, we can reduce the number of additional texture fetches from 84 to 27 thus improving the performance by up to ${\approx}30%$, depending on the platforms.