• 전자공학회논문지A
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• 제30A권8호
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• pp.42-48
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• 1993

Ar ions were implanted at 1 MeV into (100)Cz Si wafers with dose of 1 * 10$^{15}$ ions/cm$^{2}$. Damage induced by high energy implantation and its annealing behavior during rapid thermal annealing for 10sec at temperatures from 550 to 1100${\circ}C$ were investigated by crosssection transmission electron microscopy study. It can be clearly seen from the observation that the SPE(Solid Phase Epitaxy) regrowth of the buried amorphous layer induced by ion implantation proceeds from both upper and lower amorphous/crystalline (a/c) interfaces, and the activation energy for SPE from interfaces were both 1.43eV. Misfit dislocation where two interfaces met was formed and it coalesced into the hair pin dislocation in the upper regrown region. At the higher temperature after annealing out of the misfit dislocation, hair pin dislocations showed considerable drop in its bandwidth. However, they were not disappeared even at the temperature 1100${\circ}C$ with the end of range dislocation loops which were formed at the original lower a/c interface.

• Journal of Radiation Protection and Research
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• 제29권1호
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• pp.41-48
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• 2004

A safety assessment code, called SAGE (Safety Assessment Groundwater Evaluation), has been developed to describe post-closure radionuclide releases and potential radiological doses for low- and intermediate-level radioactive waste (LILW) disposal in an engineered vault facility in Korea. The conceptual model implemented in the code is focused on the release of radionuclide from a gradually degrading engineered barrier system to an underlying unsaturated zone, thence to a saturated groundwater zone. The radionuclide transport equations are solved by spatially discretizing the disposal system into a series of compartments. Mass transfer between compartments is by diffusion/dispersion and advection. In all compartments, radionuclides ate decayed either as a single-member chain or as multi-member chains. The biosphere is represented as a set of steady-state, radionuclide-specific pathway dose conversion factors that are multiplied by the appropriate release rate from the far field for each pathway. The code has the capability to treat input parameters either deterministically or probabilistically. Parameter input is achieved through a user-friendly Graphical User Interface. An application is presented, which is compared against safety assessment results from the other computer codes, to benchmark the reliability of system-level conceptual modeling of the code.

• JSTS:Journal of Semiconductor Technology and Science
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• 제5권3호
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• pp.173-181
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• 2005

A new two dimensional (2-D) model for the potential distribution of fully depleted short-channel ion-implanted silicon MESFET's has been presented in this paper. The solution of the 2-D Poisson's equation has been considered as the superposition of the solutions of 1-D Poisson's equation in the lateral direction and the 2-D homogeneous Laplace equation with suitable boundary conditions. The minimum bottom potential at the interface of the depletion region due to the metal-semiconductor junction at the Schottky gate and depletion region due to the substrate-channel junction has been used to investigate the drain-induced barrier lowering (DIBL) and its effects on the threshold voltage of the device. Numerical results have been presented for the potential distribution and threshold voltage for different parameters such as the channel length, drain-source voltage, and implanted-dose and silicon film thickness.

• 한국유체기계학회 논문집
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• 제18권2호
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• pp.54-59
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• 2015

The performance of UV reactor which is used in water treatment is strongly affected by UV fluence rate and water flow in the UV reactor. Therefore, CFD tools are widely used in designing process of UV reactors. This paper describes the development of a computational fluid dynamics (CFD) methodology that can be used to calculate the performance of open channel type UV reactor used in wastewater treatment plant. All computations were performed using commercial CFD code, CFX, by considering three dimensional, steady, incompressible flow. The Eulerian-Eulerian multi-phase method were used to capture the water-air interface. The MSSS model, provided by UVCalc3D, was used to calculate the UV intensity field. The numerical predictions and calculated UV Dose were compared with experimental dataset to validate the CFD methodology. The reactor performance based on MS2 log reduction was well matched with measurements within 6%.

• 상하수도학회지
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• 제10권2호
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• pp.55-69
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• 1996

Backwashing is one of the most important processes in water treatment. Several models have been utilized to predict minimum fluidization velocity and expansion of media. However, it is not unusual that the actual bahavior of media dose not agree well with the prediction. This study has investigated the applicability of models in predicting the minimum fluidization velocity of sand media. However even the better model has predicted minimum fluidization velocity 1.1 to 1.8 times higher than actual fluidization velocity. The expansion rate of sand media was inspected. It is found that the actual expansion rate was greater than the predicted. In this study condition, use of $d_{10}$ instead of $d_{60}$ was better to predict the expansion of media. On the contrary to the sand media, the actual expansion of anthracite media was less than that predicted. Sometimes it is reported that the dual media has been overflown during backwashing and mixed severely at the interface. It is because the grain size distribution of anthracite has not been selected properly. The numerical values for media expansion found in this study could be referred as the useful data in operating and/or designing filter media.

• The Korean Journal of Physiology and Pharmacology
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• 제8권2호
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• pp.83-88
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• 2004

The purpose of this study was to provide a basis for studying the molecular mechanism of pharmacological action of chlorhexidine digluconate. Large unilamellar vesicles (OPGTL) were prepared with total lipids extracted from cultured Porphyromonas gingivalis outer membranes (OPG). The anthroyloxy probes were located at a graded series of depths inside a membrane, depending on its substitution position (n) in the aliphatic chain. Fluorescence polarization of n-(9-anthroyloxy)stearic acid was used to examine effects of chlorhexidine digluconate on differential rotational mobility, while changing the probes' substitution position (n) in the membrane phospholipids aliphatic chain. Magnitude of the rotational mobility of the intact six membrane components differed depending on the substitution position in the descending order of 16-(9-anthroyloxy)palmitic acid (16-AP), 12, 9, 6, 3 and 2-(9-anthroyloxy)stearic acid (12-AS, 9-AS, 6-AS, 3-AS and 2-AS). Chlorhexidine digluconate increased in a dose-dependent manner the rate of rotational mobility of hydrocarbon interior of the OPGTL prepared with total lipids extracted from cultured OPG, but decreased the mobility of membrane interface of the OPGTL. Disordering or ordering effects of chlorhexidine digluconate on membrane lipids may be responsible for some, but not all of its bacteriostatic and bactericidal actions.

• 대한치과보철학회지
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• 제29권2호
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• pp.245-265
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• 1991

The purpose of this study was to observe the changes of the elemental transmission and bond strength between the metal and porcelain according to various kinds of ion beam mixing method. ion beam mixing of $meta1/SiO_2$ (silica), $meta1/Al_2O_3$(alumina) interfaces causes reactions when the $Ar^+$ was implanted into bilayer thin films using a 100KeV accelerator which was designed and constructed for this study. A vacuum evaporator used in the $10^{-5}-10^{-6}$ Torr vacuum states for the evaporation. For this study, three kinds of porcelain metal selected, -precious, semiprecious, and non-precious. Silica and alumina were deposited to the metal by the vacuum evaporator, separately. One group was treated by two kinds of dose of the ion beam mixing $(1\times10^{16}ions/cm^2,\;5\times10^{15}ions/cm^2)$, and the other group was not mixed, and analyzed the effects of ion beam mixing. The analyses of bond strength, elemental transmissions were performed by the electron spectroscopy of chemical analysis (ESCA), light and scanning electron microscope, scratch test, and micro Vickers hardness tests. The finding led to the following conclusions. 1. In the scanning electron and light microscopic views, ion beam mixed specimens showed the ion beam mixed indentation. 2. In the micro Vickers hardness and scratch tests, ion beam mixed specimens showed higher strength than that of non mixed specimens, however, nonprecious metal showed a little change in the bond strength between mixed and non mixed specimens. 3. In the scratch test, ion beam mixed specimens showed higher shear strength than that of non treated specimens at the precious and semiprecious groups. 4. In the ESCA analysis, Au-O and Au-Si compounds were formed and transmission of the Au peak was found ion beam mixed $SiO_2/Au$ specimen, simultaneously, in the higher and lower bonded areas, and ion beam mixed $SiO_2/Ni-Cr$ specimen, oxygen, that was transmitted from $SiO_2\;to\;SiO_2/Ni-Cr$ interface combined with 12% of Ni at the interface.

• 접착 및 계면
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• 제19권2호
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• pp.74-82
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• 2018

아크릴레이트 기반의 점착제를 가교 시키는 기술은 다양하게 소개되어 왔다. 본 연구에서는 에폭시 변성 단량체와 메틸아지리딘 가교제를 활용하여 높은 가교 밀도를 가지는 아크릴 구조체를 만들었다. 베이스구조체를 제조하기 위해서 빠른 제조 공정이 가능하고 무용제 공정이 가능한 UV 중합 기술을 활용했다. FT-IR, 경화거동 및 접착특성 평가를 통해 UV경화도 및 2차경화 온도에 따른 특성 변화를 확인하고자 하였다. 겔분율은 선경화 $800mJ/cm^2$, 120도 후 경화온도 조건에서 50%이상 확보할 수 있었으며, 180도 경화조건에서 80%이상 확보 할 수 있었다. 경화 시간이 길어짐에 따라 경화도가 100%에 도달하였으며 이를 통해 열경화를 통한 2차 경화가 효과적임을 확인 할 수 있었다.

• 한국방사선학회논문지
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• 제4권2호
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• pp.21-25
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• 2010

최근 진단 X선 검출기 적용을 위한 방사선 검출물질로 반도체 화합물에 대한 많은 연구가 되고 있다. 본 연구에서는 반도체 화합물 중 광민감도가 우수하고 X선 흡수율이 높은 CdS 반도체를 이용하여 검출센서를 제작하였으며, 진단 X선 발생장치에서의 에너지 영역에 대한 검출 특성을 조사함으로써 적용 가능성을 평가하였다. 센서 제작은 CdS 센서로부터의 신호 획득 및 정량화를 위한 Line voltage selector(LCV)를 제작하였으며, 전압감지회로 및 정류회로부를 설계 제작하였다. 또한 X선 노출조건에 따른 상호연과 알고리즘을 이용하였으면, DAC 컨트롤러와의 Interface board를 설계 제작하였다. 성능평가는 X선 발생장치의 조사조건인 관전압, 관전류 및 조사시간별 저항변화에 따른 전압파형 특성을 오실로스코프로 획득하여 ANOVA 프로그램을 이용하여 데이터를 통계 처리 및 분석하였다. 측정결과, 관전압과 관전류이 증가할수록 오차의 비가 감소하였으며, 90kVp에서 6%, 320 mA에서 0.4% 이하의 좋은 특성을 보였으며, 결정계수는 약 0.98로 1:1의 상관관계를 보였다. X선 조사시간에 따른 오차율은 CdS 물질의 늦은 반응속도에 기인하여 조사시간이 길어질수록 지수적으로 감소하는 것을 알 수 있었으며, 320 msec에서 2.3%의 오차율을 보였다. 끝으로 X선 선량에 따른 오차율은 약 10% 이하였으며, 0.9898의 결정계수로 매우 높은 상관관계를 보였다.

• 한국방사선학회논문지
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• 제14권5호
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• pp.529-535
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• 2020

Geant4는 C++ 언어사용에서 windows 운영체계와 호환이 가능해져, DICOM이나 소프트웨어를 연계하는 인터페이스 기능이 가능해졌다. 기하학적 고형물에 의해 인체 장기를 나타내는 팬텀은 치료나 진단에서 선량 계획과 같은 의학 용도에 널리 사용된다 방사선 방호 목적을 위해서는 에너지가 몇 keV의 일때 설명의 유효성을 보여주는 것일 여전히 필요하다. 본 연구에서는 Geant4 시뮬레이션을 통해 저 keV부터 고 keV까지 다양하게 에너지를 선택하여 인간 팬텀중 일부분을 선택하여 광자 병렬 평면 필드에서 조사했을 때 그 장기에 대한 방사선량을 구하고 Zankl의 승인된 방법에 의해 얻은 결과에 대해 결과를 비교 검증하고자 한다. 몬테카롤로 코드를 사용하여 장기 선량을 평가하는 것의 중요성은 시뮬레이션의 다양한 묘사 및 특성에 의해 중성자, 양성자, 파온 등과 같은 빔의 여러 가지 유형의 입자와 Gev와 같은 높은 에너지에도 적합하다는 것을 확인하였다.