• 전기전자학회논문지
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• 제27권3호
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• pp.327-332
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• 2023

전통적인 실리콘 기반 반도체 소자 보다 높은 성능과 다양한 활용성으로 차세대 반도체 후보로 높은 관심 받고 있는 CNTFET은 CNT 배치와 같은 CNTFET만의 고유한 공정 편차가 아직 성숙되지 않아 상용화에 어려움을 겪고 있다. 이러한 어려움을 극복하고자 반복적인 회로 구성으로 공정 편차의 영향을 적게 받는 회로를 MOSFET-CNTFET 기반 하이브리드 회로로 구현하여 CNTFET 의 장점을 취하고 단점을 보완하고자 하는 수많은 연구들이 지속적으로 수행되어 왔다. 본 논문에서는 하이브리드 SRAM의 성능이 기존의 MOSFET SRAM 또는 CNTFET SRAM에 존재하는 반도체 공정 변화에 의해 얼마나 변화될 수 있는지를 비교하였다. 시뮬레이션 결과, CNT 밀도를 32nm 당 7개에서 9개 사이로 유지할 수 있다면, hybrid SRAM은 기존 MOSFET SRAM보다 읽기 동작에서 그리고 쓰기 동작에서 공정 편차에 대한 강건성이 각각 약 2.6배 그리고 약 1.1배 있음을 보여준다.

• 대한조선학회논문집
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• 제60권1호
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• pp.38-47
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• 2023

According to the government policy of environmental regulations, interest of ship, which made with High-Density Polyethylene (HDPE) as a low-carbon and eco-friendly material, is growing as a substitute for the existing fishery boat hull materials such as FRP, aluminum, steel etc. However, regulations related to the production of HDPE ship are still quite incomplete. Even there are no regulations related to structural analysis. Therefore, in this study, structural analysis is carried out by applying different design loads for each international classification for 38ft class HDPE power boats, and the results are compared and analyzed. According to this study, although there is a correlation between the based pressure value and the analysis result value of each class regulation, it is not necessarily proportional. Also, This analysis result shows a difference not only depending on the size of design load, but also application range of the load, the pressure adjustment factor and section shape. However, the occurrence point and trend of the maximum stress values were quite consistent. It is hoped that the results of this study will be used when establishing HDPE ship structure analysis procedures and standards in the future.

• Nuclear Engineering and Technology
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• 제55권2호
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• pp.655-668
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• 2023

In radiography, an antiscatter grid is a well-known device for eliminating unexpected x-ray scatter. We investigate a new stationary grid artifact suppression method based on a nonsubsampled contourlet transform (NSCT) incorporated with Gaussian band-pass filtering. The proposed method has an advantage that extracts the Moiré components while minimizing the loss of image information and apply the prior information of Moiré component positions in multi-decomposition sub-band images. We implemented the proposed algorithm and performed a simulation and an experiment to demonstrate its viability. We did this experiment using an x-ray tube (M-113T, Varian, focal spot size: 0.1 mm), a flat-panel detector (ROSE-M Sensor, Aspenstate, pixel dimension: 3032 × 3800 pixels, pixel size: 0.076 mm), and carbon graphite-interspaced grids (JPI Healthcare, 18 cm × 24 cm, line density: 103 LP/inch and 150 LP/inch, ratio: 5:1, focal distance: 65 cm). Our results indicate that the proposed method successfully suppressed grid artifacts by reducing them without either reducing the spatial resolution or causing negative side effects. Consequently, we anticipate that the proposed method can improve image acquisition in a stationary grid x-ray system as well as in extended x-ray imaging.

• 한국물환경학회지
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• 제38권6호
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• pp.282-291
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• 2022

Since the efficiency of wastewater treatment using microalgae differs depending on the metabolic characteristics of the species, it is important to understand the characteristics of target algae prior to the application in wastewater treatment. In this study, for the application of Arthrospira platensis to wastewater treatment, which is a filamentous alkaliphilic cyanobacteria, basic species specificity was identified and the possibility of application to wastewater treatment was investigated. As a result of the species specificity investigation, the specific growth rate between pH 7.0 and 11.0 showed the highest value near pH 9 at 0.25/day. The reason for the relatively low growth(0.08/day) at pH 11 was thought to be the CA(carbonic anhydrase) enzyme that is involved in carbon fixation during photosynthesis has the highest activity at pH 8.0 to 9.0, and at pH 11, CA activity was relatively low. In addition, A. platensis showed optimal growth at 400 PPFD(photosynthetic photon flux density) and 30℃, and this means that cyanobacteria such as A. platensis have a larger number of PS-I(photosystem I) than that of PS-II(photosystem II). It was speculated that it was because higher light intensity and temperature were required to sufficiently generate electrons to transfer to PS-I. Regarding the applicability of A. platensis, it was suggested that if a system using the synergistic effect of co-culture of A. platensis and bacteria was developed, a more efficient system would be possible. And different from single cocci, filamentous A. platensis expected to have a positive impact on harvesting, which is very important in the latter part of the wastewater treatment process.

• 한국수소및신에너지학회논문집
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• 제33권1호
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• pp.38-46
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• 2022

Two different gas diffusion layers having noticeable differences in micro-porous layer's (MPL's) crack were studied as a substrate for the gas diffusion electrode (GDE) with different binder/carbon (B/C) ratios in high-temperature polymer electrolyte fuel cell (Ht-PEMFC). As a result, the performance defined as the voltage at 0.2 A/cm² and maximum power density from the single cells using GDEs from H23 C2 and SGL38 BC with different B/C ratios were compared. GDEs from H23 C2 showed a proportional increase of the voltage with the binder content on the other hand GDEs from SGL38 BC displayed a proportional decline of the voltage to the binder content. It was revealed that MPL crack influences the structure of catalyst layer in GDEs as well as affects the RC_athode which is in close connection with the Ht-PEMFC performance.

• 한국수소및신에너지학회논문집
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• 제34권3호
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• pp.283-291
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• 2023

The physical properties were analyzed for four gas diffusion layers, and gas diffusion electrodes (GDEs) for the cathode of high-temperature polymer electrolyte membrane fuel cell were fabricated through bar coating with three binder to carbon (B/C) ratios. Among them, The GDE from JNT30-A6P showed a significant change in secondary pore volume at a B/C ratio of 0.31, which had the largest pore volume among all GDEs. In the polarization curve, JNT30-A6P GDE showed the best membrane electrode assembly (MEA) performance with a peak power density of 384 mW/cm² at a a B/C ratio of 0.31. From the distribution of relaxation time analysis, the peak 1 corresponding to mass transfer resistance of oxygen reduction reaction (ORR) was significantly reduced in the JNT30-A6P GDE. This is the result that when the binder content decreased, the volume of the secondary pore increased, and the mass transfer resistance of ORR decreased, which played an essential role in the MEA performance.

• 한국건설순환자원학회논문집
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• 제11권4호
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• pp.501-508
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• 2023

이 연구는 도시화와 교통량 증가로 인해 심화되는 환경 소음 문제에 대응하여, 친환경적인 무기계 흡음 패널을 개발함으로써 기존의 PMMA 및 시멘트 기반 패널의 한계를 극복하고자 한다. 이러한 전통적인 패널들은 가연성으로 인한 안전 위험과 탄소 배출로 인한 환경 문제를 가지고 있다. 산업폐기물을 활용한 이 연구는 두 단계로 구성된다: 첫째, 물리적 및 성능적 특성(유동성, 밀도, 압축 강도, 흡음률)에 대한 기초 시험, 둘째, 최적화된 패널 혼합물의 개발. 이 접근 방식은 기존 패널을 지속 가능하고 효과적인 대안으로 대체하고자 하며, 안전하고 환경적으로 책임 있는 도시 인프라에 중요한 기여를 목표로 한다. 연구 결과는 방음 패널 시장에 대한 새로운 해결책을 제시하며, 소음 제어와 함께 환경 및 안전 기준에 부합하는 혁신을 추구한다.

• 한국수소및신에너지학회논문집
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• 제34권6호
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• pp.581-586
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• 2023

As the development of alternative energy is required due to the depletion of fossil fuels, interest in the use of hydrogen energy is increasing. Hydrogen is a promising clean energy source with high energy density and can lead to the application of environmentally friendly technologies. However, due to difficulties in production, storage, and transportation that prevent the application of hydrogen-based eco-friendly technology, research on reforming reactions using dimethyl ether (DME) is being conducted. Unlike other hydrocarbons, DME is attracting attention as a hydrogen carrier because it has excellent storage stability and transportability, and there is no C-C bond in the molecule. The reaction between DME and steam is one of the reforming processes with the highest hydrogen yield in theory at a temperature lower than that of other hydrocarbons. In this study, a hydrogen reforming device using DME was developed and a catalyst prepared by supporting Cu in alumina was put into a reactor to find optimal hydrogen production conditions for supplying hydrogen to fuel cells while changing reaction temperature (300-500℃), pressure (5-10 bar), and steam/carbon ratio (3:1 to 5:1).

• 전자통신동향분석
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• 제38권6호
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• pp.41-51
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• 2023

Heat dissipation technology for semiconductors and electronic packaging has a substantial impact on performance and lifespan, but efficient heat dissipation is currently facing limited improvement. Owing to the high integration density in electronic packaging, heat dissipation components must become thinner and increase their performance. Therefore, heat dissipation materials are being devised considering conductive heat transfer, carbon-based directional thermal conductivity improvements, functional heat dissipation composite materials with added fillers, and liquid-metal thermal interface materials. Additionally, in heat dissipation structure design, 3D printing-based complex heat dissipation fins, packages that expand the heat dissipation area, chip embedded structures that minimize contact thermal resistance, differential scanning calorimetry structures, and through-silicon-via technologies and their replacement technologies are being actively developed. Regarding dry cooling using single-phase and phase-change heat transfer, technologies for improving the vapor chamber performance and structural diversification are being investigated along with the miniaturization of heat pipes and high-performance capillary wicks. Meanwhile, in wet cooling with high heat flux, technologies for designing and manufacturing miniaturized flow paths, heat dissipating materials within flow paths, increasing heat dissipation area, and reducing pressure drops are being developed. We also analyze the development of direct cooling and immersion cooling technologies, which are gradually expanding to achieve near-junction cooling.

• Korean Chemical Engineering Research
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• 제61권4호
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• pp.550-554
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• 2023

탄화수소기반의 화석연료 에너지원은 이산화탄소 배출로 인한 지구온난화 문제로 지속적인 이용 및 확장에 제한이 있다. 수소는 전통적인 화석연료에 대한 유망한 대안으로 여겨지고 있다. 수소의 안정적인 장기저장을 위해서 극저온인 포화상태에서 수소의 열역학적 물성에 대한 예측이 요구된다. 따라서 본 연구에서는 비교적 간단한 관계식을 보이는 3차 상태방정식들을 이용하여 포화상태의 열역학적 물성들(포화증기압, 액체 및 기체의 밀도, 엔탈피 및 엔트로피)을 모사하였다. 포화상태 수소에 대한 여러가지 열역학적 물성들을 비교한 결과 3 종류(Redlich-Kwong (RK), Soave-Redlich-Kwong (SRK), Peng-Robinson (PR))의 상태방정식 중 SRK 모델이 비교적 정확한 예측결과를 보였다.