• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2003년도 춘계학술대회논문집
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• pp.49-52
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• 2003

The effects of nitrogen on the deformation behavior of duplex stainless steel have been studied The variation of strength was correlated with the characteristic microstructures. Analysis based on Hall-Petch relation confirmed that nitrogen enhances phase-boundary strengthening effect. The evolution of dislocation structure, slip traces, and misorientation distribution during deformation were also characterized to elucidate the effect of nitrogen on inelastic deformation mechanism.

• 한국과학예술포럼
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• 제29권
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• pp.89-100
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• 2017

본 연구의 목적은 전시홀 공간특성의 구성요소를 도출하고 그 요소들이 참관객 태도에 어떠한 영향을 미치는지에 관하여 이론적 모텔을 정리하고 이를 실증적으로 분석함으로써 전시주최자가 전시참관객을 유치하기 위해 전략을 수립하는 데에 시사점을 제시하고자 실행되었다. 본 연구의 목적 달성을 위해 연구와 관련된 이론을 정립하기 위한 문헌연구 고찰과 이를 토대로 연구모형을 설계하여 실증분석을 실시하였다. 설문조사는 2016년 10월 28일부터 11월 5일까지 서을 COEX에서 개최한 전시회를 방문한 참관객을 대상으로 총 320부의 설문지를 배부하였고 전부 회수되었으며 최종적으로 총 303부가 실증분석에서 사용되었다. 실증분석은 SPSS 24.0으로 구현되었다. 연구결과는 전시홀 공간특성의 각 구성요소들은 참관객 지각적태도에 유의한 영향을 미치는 것으로 나타났으며 참관객 행동적 태도에 일부 유의한 영향을 미치는 것으로 나타났다. 또한, 전시홀 공간특성의 각 요인들은 접근성, 심미성, 쾌적성, 편리성 순으로 참관객 지각적 태도에 영향을 미치는 것으로 나타났다. 이러한 연구결과를 반영하여 향후 전시홀 내의 부스배치, 사설물 배치, 실내 공간의 매력, 실내 온도와 조명 등의 장점을 더욱 강화시키고 실내 휴식공간 등의 부족한 부분을 개선해나가면 더 많은 참관객 유치 가능성이 높아질 것으로 유추해 볼 수 있다. 이상과 같이 본 연구는 전시홀 공간특성이 참관객 태도에 미치는 영향을 실증 분석하여 보다 더 매력적이고 쾌적하고 접근성이 좋은 전시홀 환경을 제공할 수 있는 전시홀 공간의 전략적 경영방안을 마련하는데 지침을 제공하였다는데 의미가 있다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1991년도 하계학술대회 논문집
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• pp.187-190
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• 1991

The analytical model to investigate the effects of the drift and diffusion carrier transport upon the Hall effect is presented and applied to the general PN junction structure. The diffusion current effect on the Hall coefficient can not be considered in the conventional model, which produces the conversion of the direction of the induced Hall field between measured and calculated values. The proposed analytical model which considers the diffusion current effect provides the coincident results with the previous experimental results.

• Journal of Power Electronics
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• 제18권4호
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• pp.1086-1098
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• 2018

This study presents a new sensorless commutation method for brushless direct current motors to replace Hall sensor signals with virtual Hall signals. The importance of the proposed method lies in the simultaneous elimination of the phase shifter and the low-pass filters, which makes the method simple and cost-effective. The method removes high ripple switching noises from motor terminals, thereby decreasing motor losses. The proposed method utilizes unfiltered line voltages with notches caused by current commutation. Hence, specific sign signals are defined to compensate for the effects of commutation noise. The proposed method is free from phase delay that originates from low-pass filters. The method directly produces virtual Hall signals, and thus, it can be interfaced with low-cost commercial commutation integrated circuits based on Hall sensors. Simulation and experimental results show the effectiveness and validity of the proposed method.

• Journal of the Korean Society for Industrial and Applied Mathematics
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• 제24권1호
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• pp.103-119
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• 2020

In this work, the hydromagnetic and thermal characteristics of natural convection flow in a vertical parallel plate micro-porous-channel with suction/injection is analytically studied in the presence of Hall current by taking the temperature jump and the velocity slip at the wall into account. The governing equations, exhibiting the physics of the flow formation are displayed and the exact analytical solutions have been obtained for momentum and energy equations under relevant boundary conditions. The impact of distinct admissible parameters such as Hartmann number, Hall current parameter, permeability parameter, suction/injection parameter, fluid wall interaction parameter, Knudsen number and wall-ambient temperature ratio on the flow formation is discussed with the aid of line graphs. In particular, as rarefaction parameter on the micro-porous-channel surfaces increases, the fluid velocity increases and the volume flow rate decreases for injection/suction.

• 한국세라믹학회지
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• 제54권6호
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• pp.506-510
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• 2017

One of the characteristics of polycrystalline graphene that determines its material properties is grain size. Mechanical properties such as Young's modulus, yield strain and tensile strength depend on the grain size and show a reverse Hall-Petch effect at small grain size limit for some properties under certain conditions. While there is agreement on the grain size effect for Young's modulus and yield strain, certain MD simulations have led to disagreement for tensile strength. Song et al. showed a decreasing behavior for tensile strength, that is, a pseudo Hall-Petch effect for the small grain size domain up to 5 nm. On the other hand, Sha et al. showed an increasing behavior, a reverse Hall-Petch effect, for grain size domain up to 10 nm. Mortazavi et al. also showed results similar to those of Sha et al. We suspect that the main difference of these two inconsistent results is due to the different modeling. The modeling of polycrystalline graphene with regular size and (hexagonal) shape shows the pseudo Hall-Petch effect, while the modeling with random size and shape shows the reverse Hall-Petch effect. Therefore, this study is conducted to confirm that different modeling is the main reason for the different behavior of tensile strength of the polycrystalline structures. We conducted MD simulations with models derived from the Voronoi tessellation for two types of grain size distributions. One type is grains of relatively similar sizes; the other is grains of random sizes. We found that the pseudo Hall-Petch effect and the reverse Hall-Petch effect of tensile strength were consistently shown for the two different models. We suspect that this result comes from the different crack paths, which are related to the grain patterns in the models.

• 인간식물환경학회지
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• 제22권1호
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• pp.15-29
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• 2019

The purpose of this study is to investigate the effects of the exhibition displays and events of the Agro-healing Experience Hall in the Agricultural Technology Exhibition 2018 on satisfaction and revisit intention of visitors. A survey was conducted on visitors of the Agro-healing Experience Hall and the responses of 274 visitors excluding 26 cases with inappropriate responses were analyzed. For psychological measurement, the Perceived Restorativeness Scale (PRS), Profile of Mood States (POMS), level of plant gardening experience, satisfaction and loyalty were measured. There was a significant difference among age groups in all four factors of the PRS (repose, fascination, coherence, and legibility). In the case of education level, there was a significant difference in the three factors (repose, fascination, and legibility). In addition, average monthly income showed a significant difference among groups in the two factors (fascination and coherence). As a result of analyzing the mood states of visitors for the exhibition events of the Agro-healing Experience Hall, there was a significant difference among age groups only in the case of vigor (p < .05). As a result of analyzing the correlation between the level of plant gardening activities (3 factors) and PRS (4 factors) in the exhibition events of the Agro-healing Experience Hall, plant preference tendency and plant-related event showed a high positive correlation of 0.5 or more with repose of the PRS factors. A multiple regression analysis was conducted to investigate the effects of the level of plant gardening activities, PRS and POMS on the satisfaction and loyalty of visitors. As a result, it was found that in terms of relative explanatory power over independent variables affecting satisfaction and revisit intention, fascination had the greatest effect, followed by vigor, fatigue, and occupation (company employee). The results of this study suggest that exhibition events of the Agro-healing Experience Hall affect repose, fascination or vigor of visitors, and thus can be used positively to increase satisfaction and revisit intention of visitors.

• 한국산업융합학회 논문집
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• 제13권3호
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• pp.145-151
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• 2010

This study is for getting basic data through grasping the obtained heat by structure of each unit and the effects of environment improvement based on judgement for whether or not a solar heating system of renewable energy installations is possible to set up in village hall public buildings as community center and senior citizen center. Conducting a survey of community center and senior citizen center in Ibam-Myon, Yeongyang-Gun, Gyeongsangbuk-Do and the analysis, obtained solar heat of 414,309,678 kcal every year and from this, effects of 131.48995 $TCO_2$. These figure equate to 26,298 pines effect. These results show that the advantage of reducing building operating costs in the long run besides effects of environment improvement.

• 한국항공우주학회지
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• 제43권4호
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• pp.377-386
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• 2015

본 논문에서는 국내에서 개발된 인공위성 중 최초로 홀 추력기(Hall-effect Thruster)를 탑재한 두바이셋-2(DubiaSat-2)호의 궤도를 분석하여 홀 추력기의 성능을 검증하였다. 두바이셋-2호가 발사된 2013년 11월 21일(UTC) 이후 8개월간의 초기 궤도 운용을 위한 준비 및 수행 결과들에 대해 중점을 두었으며, 임무 수행 기간 중 태양활동이 궤도 변화에 미치는 영향력을 함께 분석하였다. 특히, 증가한 추력에 따른 실제 궤도 변화와 예측된 궤도를 비교하여 분석한 결과 홀 추력기는 지상 실험 결과와 유사한 11 mN 추력을 발생하고 있는 것을 확인하였다. 본 논문에서 정리된 내용은 추후 홀 추력기를 탑재한 인공위성의 초기 및 정상 임무기간 동안 궤도 운용 시 안정성과 효율성을 높이는데 주요 참고자료가 될 것으로 판단된다.

• International Journal of Aeronautical and Space Sciences
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• 제15권3호
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• pp.320-334
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• 2014

Over the last two decades, numerous experimental and numerical efforts have examined physical phenomena in plasma discharge devices. The physical mechanisms that govern the anomalous electron diffusion from the cathode to the anode in the Hall Effect Thruster (HET) are not fully understood. This work used 1-D numerical method to improve our understanding and gain insight into the effect of the anomalous electron diffusion in the HET. To this end, numerical solutions are compared with various experimental HET performance measurements and the effects of anomalous electron diffusion are analyzed. The relationships between the anomalous electron diffusion and important parameters of the HET are also studied quantitatively. The work identifies the cathode mass flow rate fraction, radial magnetic field distribution, and discharge voltage as significant factors that affect anomalous electron diffusion. Additionally, the study demonstrates a computational process to determine the radial magnetic field distribution required to achieve specific thruster performance goals.