• 한국입자에어로졸학회지
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• 제19권3호
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• pp.89-100
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• 2023

In our previous study, a wire-plate type electrostatic precipitator (ESP) was developed to collect bioaerosols of 100 nm size. In the study, various flow rates (40 ~ 100 L/min) and applied voltages (3 ~ 10 kV) were tested for experiment. In this study, numerical analysis was performed for the ESP of the previous study with the same flow rates and applied voltages, but with varying the size of bioaerosols to 0.04 ~ 2.5 ㎛. Overall, the numerical analysis results well predicted the experimental data. Bioaerosols of 0.1 ~ 0.5 ㎛ showed the minimum collection efficiency for all conditions because of low charge number. The effect of the ionic wind generated by the corona discharge was calculated. However, the ionic wind did not affect much the collection efficiency. The aerosol collection in the ESP of this study was due to the electrostatic force generated by particle charge in the electric field. This numerical study on the ESP can be used for the design and optimization of higher flow rate (> 100 L/min) ESP.

• 한국의류학회지
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• 제47권6호
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• pp.1204-1220
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• 2023

With the rising importance placed on sustainability for brands, a plethora of research addresses consumer responses concerning eco-friendly products. While positive effects of eco-friendly traits on beauty products have been discussed, this study addresses a wide research gap in the makeup category. Based on the goal-attribute theory and the lay theory of ethicality, detrimental effects of eco-friendly ingredient claims on perceived appearance enhancement attributes (AEA) were examined. A between-subject, single-factor (eco-friendly ingredient claims present vs. absent) web-based experimental design tested the effect of conditions on makeup products that emphasized AEA. Results found a negative effect of eco-friendly ingredient claims on perceived AEA, supporting previous literature regarding the 'green gap'. Evidence showed that perceived AEA fully mediated the effect of eco-friendly claims on purchase intention, which was moderated by AEA preference. Interestingly, findings show that the purchase intention of respondents with a near-average preference for AEA was not moderated. Results contribute to preexisting literature by extending the lay theory of ethicality and product function mismatch to the field of makeup. Managerial implications are discussed, including opportunities for eco-friendly makeup products to appeal to alternative benefits.

• 대한임베디드공학회논문지
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• 제18권5호
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• pp.203-208
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• 2023

Recently, with the growing interest in the field of autonomous driving, many researchers have been focusing on developing autonomous driving software platforms. In particular, we have concentrated on developing 3D object detection models that can improve real-time performance. In this paper, we introduce a self-constructed 3D LiDAR dataset specific to domestic environments and propose a VariFocal-based CenterPoint for the 3D object detection model, with improved performance over the previous models. Furthermore, we present experimental results comparing the performance of the 3D object detection modules using our self-built and public dataset. As the results show, our model, which was trained on a large amount of self-constructed dataset, successfully solves the issue of failing to detect large vehicles and small objects such as motorcycles and pedestrians, which the previous models had difficulty detecting. Consequently, the proposed model shows a performance improvement of about 1.0 mAP over the previous model.

• 한국전산구조공학회논문집
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• 제28권3호
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• pp.275-281
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• 2015

본 연구에서는 동조액체기둥감쇠기의 비선형감쇠항을 등가점성감쇠항으로 치환한 등가선형 동조액체기둥감쇠기 모델을 유도하였으며 동조액체기둥감쇠기의 동적거동인 고유진동수와 감쇠비를 이론적으로 파악하였다. 동조액체기둥감쇠기에 일정한 전기장을 형성한 후 동조액체기둥감쇠기의 수직운동에 의해 발생되는 가변전압을 측정하여 수조 내부의 수위로 변환하는 식을 유도하였다. 또한 본 연구에서 제안한 동조액체기둥감쇠기의 수위측정 시스템의 타당성을 검증하기 위하여 고가의 전기 용량식 파고계와 비교 및 검증하였다. 마지막으로 본 연구에서 제안한 수위측정 시스템을 동조액체기둥감쇠기에 적용, 진동대 실험을 실시하여 고유진동수와 감쇠비를 파악하였고, 이론상의 고유진동수와 실험상의 고유진동수가 일치하였음을 확인하였으며, 진동수비 변화에 따른 동조액체기둥감쇠기의 감쇠비 변화를 확인하였다.

• 대한조선학회논문집
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• 제49권2호
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• pp.203-211
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• 2012

The main object of this experiment is to estimate the hydrodynamic forces acting on a submerged streamlined body placed in a one-end-opened cylindrical tube moving with certain translational velocity. The best experimental design for this object is mimicking real situation, however sizes of model body and cylinder tube are just the same as those of real, for avoiding scale effects, mimicking real situation is not realizable. Hence, in this experiment, target body and cylindrical tube were designed to be towed with varying body position relative to cylindrical tube. For measuring hydrodynamic forces and flow velocity in the cylindrical tube, six one-component load cells and several one-hole Pitot tubes were used. Several conditions were checked with various end-plates those had different opening areas. Experiment results show that forces and flow velocity had different tendency with those expected, and the presence of a end-plate slows down the flow velocity in the cylindrical tube and affects pressure field in the tube to push the model submerged body forward of the tube. This tendency grows with decreasing opened area.

• 대한조선학회지
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• 제26권2호
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• pp.1-12
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• 1989

본 논문에서는 선체로부터 멀리 전파해 나아가는 선형파와 선체 가까이에 존재하는 쇄파로 인한 조파저항성분을 최소화시키는 방법을 보여준다. 본 방법은 선형조파저항의 최적화 방법과 시험자료 분석을 통한 쇄파저항의 통계적 최적화방법으로 구성된다. 응용목적으로서, 수선형상이 포물선이고 측면이 수직한 모형을 기본선형으로 택하였고, 선형파를 최적화하는 방법과 경험적인 방법을 통하여서 선체전반부의 횡단면적 곡선을 변화시킨 두척의 수정모형선을 얻었다. 3척의 선형에 대한 시험 및 분석결과로부터 선체전반부의 횡단면적 곡선의 변화에 따른 선형파저항과 쇄파저항과의 상관관계를 살펴보았다. 본 방법으로 선체전반부가 최적화된 선형은 설계속도($F_n=0.26$)에서 기본선형에 비하여 약 47%의 조파저항감소를 보이고 있다.

• 한국지반환경공학회 논문집
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• 제17권10호
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• pp.33-43
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• 2016

피복공법의 설계에서 피복재의 선정은 중요한 설계 변수로 파랑에너지로 발생하는 해저면 유속에도 피복재가 침식되지 않게 설계되어야 한다. 피복공법 관련된 기존 연구는 파랑에너지에 따른 깊이별 유속과 유효입경을 주로 시공경험과 수치해석에 의존하여 수행되었기 때문에 현장에서 시공경험이 미흡한 기술자가 사용하기에는 어려움이 예상된다. 본 연구에서는 파랑에너지에 따른 깊이별 유속과 피복재의 입경에 따른 침식을 판단할 수 있는 간편식을 제시하고 모형수조를 이용한 실내실험을 통해 신뢰성을 확인하고자 한다. 실내실험에서 측정된 깊이별 유속은 이론식과 상당히 일치하며, 유속추정 이론식을 침식 해석에 적용하여 유효입경을 예측하면 침식 유무 판단이 가능하다.

• 물과 미래
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• 제10권2호
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• pp.81-90
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• 1977

The research is conducted to study the effect of the soil physical properties in the direct sowing culture on the water requirement, growth, and yield of rice with Early-Tongil at the experimental paddy field of the Sangju agri. and seri. junior college in Keyngbuk province from 6th May to 15th September in 1977. The experimental plots are designed with the four plots which are non-irrigated standard (plowing to 15cm), non-irrigated deep lowed (plowing to 25cm), irrigated standard (plowing to 15cm), and irrigated deep plowing plot (plowing to 25cm) and also each plot is repreated four times by the split plot design. The results obtained are summarized as follows: 1) The soil sample was ML to 10cm depth from ground surface and those from 10cm to 20cm depth and from 20cm to 30cm were CL. Each specific gravity was 2. 6, 2. 6 and 2. 7. 2) The weather during culturing period was the sane as the normal year of mean temperature. The precipitation was little and the distribution of it was disordered comparing to normal year but the heavy sunshine gave good effect on ripening. 3) Percolation loss was increased more at the non-irrigated plot than at the irrigated plot, and that of deep-plowed plot was increased more. 4) Grain yield per 10a. of non-irrigated deep plowed plot was 898kg, it was greated than others but there wa no significance. 5) A significant difference in the number of spikelets per panicle was found between nonirrigated plot and irrigated plot, and the number of spiklelets per panicle at the nonirrigated plot was more than that of the irrigated plot. But there was no significance in the other yield components-number of panicle, fertility abd ripening ratio-at the irrigated plot, ut weight of 100 grains was higher at non-irrigated plot. 6) Yield and growth at the deep plowed plot were higher than those of standard plowed plot.

• 한국도로학회논문집
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• 제8권1호
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• pp.139-152
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• 2006

Many experimental and numerical approaches have been developed to evaluate paving materials and to predict pavement response and distress. Micromechanical simulation modeling is a technology that can reduce the number of physical tests required in material formulation and design and that can provide more details, e.g., the internal stress and strain state, and energy evolution and dissipation in simulated specimens with realistic microstructural features. A clustered distinct element modeling (DEM) approach was implemented In the two-dimensional particle flow software package (PFC-2D) to study the complex behavior observed in asphalt mixture fracturing. The relationship between continuous and discontinuous material properties was defined based on the potential energy approach. The theoretical relationship was validated with the uniform axial compression and cantilever beam model using two-dimensional plane strain and plane stress models. A bilinear cohesive displacement-softening model was implemented as an intrinsic interface and applied for both homogeneous and heterogeneous fracture modeling in order to simulate behavior in the fracture process zone and to simulate crack propagation. A disk-shaped compact tension test (DC(T)) with heterogeneous microstructure was simulated and compared with the experimental fracture test results to study Mode I fracture. The realistic arbitrary crack propagation including crack deflection, microcracking, crack face sliding, crack branching, and crack tip blunting could be represented in the fracture models. This micromechanical modeling approach represents the early developmental stages towards a 'virtual asphalt laboratory,' where simulations of laboratory tests and eventually field response and distress predictions can be made to enhance our understanding of pavement distress mechanisms, such its thermal fracture, reflective cracking, and fatigue crack growth.

• 한국추진공학회지
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• 제10권4호
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• pp.100-108
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• 2006

실험적인 연구가 흡입구와 배기구 성능을 평가하는 일반적인 방법이나 이는 고가이며 많은 시간이 소요된다. 따라서 소요 시간과 계산을 절약하는 방법으로 전산 유체 역학적 수치 모사가 실험적 연구로 대체할 수 있다. 그러므로 본 연구는 3차원 형상 모델을 이용하여 흡입구와 배기구의 구성품 성능을 연구하는 것을 목표로 하였다. 본 연구에서 특정한 흡입구 및 배기구를 유동가시화 기능을 갖는 전산유체 역학적 프로그램을 이용하여 손실 및 유동장을 예측하기 위해 모델링 및 해석이 수행되었다. 모델링된 기하학적 자료를 필요로 하는 과정이 설계과정에서 설계 개선 가능성을 위해 요구되었다. 또한 특정 터보축 엔진의 장착 성능이 예측된 흡입구, 배기구 및 기타 보기 손실을 가지고 평가되었다.