• 한국생산제조학회지
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• 제26권4호
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• pp.351-356
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• 2017

The resistance of printed patterns for electrodes fabricated using printing technology should be minimized. This parameter depends on the pattern width and thickness; however, from the viewpoint of printability, the printed patterns should be printed at the designed width. The resistance of the printed patterns as well as printability is affected by various printing conditions. In this paper, the printing condition is optimized to minimize the resistance of electrodes printed by the roll-to-roll gravure method. This is done by considering the spread ratio of pattern width as a parameter of printability using design experiments. The drying temperature, dryer fan speed, and printing speed are selected as effective factors for the experiment objective. The optimized conditions are obtained and reproducibility test using these demonstrates that the optimized conditions can produce low-resistance electrodes for printability of the pattern width.

• Journal of Power Electronics
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• 제13권4호
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• pp.619-625
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• 2013

Switched mode power supplies (SMPS) are power electronic circuits extensively used in a wide range of applications. High frequency switching operation of SMPS causes electromagnetic emissions and has the potential to interfere with system operation, which in turn has an impact on system performance. This makes electromagnetic compatibility (EMC) an important concern. In this paper, a new and simple spread spectrum technique is proposed by modulating chaotic pulse position modulation (CPPM) and pulse width modulation (PWM). The resulting CPWM is implemented to reduce the conducted EMI in SMPS. The proposed method is found to be effective in reducing conduction EMI. The effectiveness and simplicity of the proposed method on spreading those dominating frequencies is compared to the EMI mitigation technique using an external chaotic generator. Finally, the levels of conductive EMI with standard PWM, CPWM with an external chaos generator and the proposed method are experimentally verified to comply with the CISPR 22A regulations. The results confirm the effectiveness of the proposed method.

• 대한전자공학회논문지
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• 제22권1호
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• pp.1-6
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• 1985

Defocussed된 정지화상은 그 PSF(point spread fufction)이 rectangular 혹은 Gaussian등의 2차함수가 되며 이것과 입력화상과의 convolution으로 모델링 할 수 있음이. 알려져 있다. 그런데 이를 TV카메라의 주사선을 이용한 analog 방식으로 개선코자 할 경우에는 매 수평주사선에 관한한 1차원적인 처리가 가능하며 이 defocussed된 화상은 원래의 화상과 일정한 폭을 가진 펄스와의 수평방향으로 convolution된 결과로 해석 할 수 있음을 밝혔다. 또한 TV 카메라의 analog compound high pass filter를 사용한 복구 실험으로써 현저히 개선된 사진을 얻을 수 있있다.

• 천문학회지
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• 제36권spc1호
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• pp.117-124
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• 2003

Pre-launch calibration data have been analyzed for evaluating the point spread function (PSF) of Yohkoh Soft X-ray Telescope (SXT). Especially, it is found crucial that the effect of undersampling should be treated properly. The best fit solution of the SXT PSF, which is modeled by an elliptical Moffat function, has been derived by the comparison with the ground experiment data. In order to examine the off-axis variation of the SXT PSF, we need to define in advance the location of the optical axis on the CCD. According to the previous studies, the off-axis variation of effective area (the vignetting function) may be approximated either by two non-concentric cones or by a cone with some flat distortions. There have been, however, no fully approved representations for the SXT vignetting effect. The effect of the shift of the optical axis from the geometrical center of the telescope is investigated by numerical simulation. It is revealed from our study that the full width at half maximum (FWHM) of the SXT PSF stays nearly constant within an error bound over the central area of the CCD where the solar disk is located.

• 한국화재소방학회논문지
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• 제31권5호
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• pp.28-36
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• 2017

본 논문에서는 공연장 무대 화재 시 객석으로의 연기 확산에 방화막 및 강제 배연구가 미치는 영향에 대하여 Fire Dynamics Simulator (FDS)를 이용하여 연구를 수행하였다. 폭 31 m, 깊이 34 m, 높이 32 m의 무대에 대하여, 10 MW의 열방출률과 화재성장속도가 fast인 화재를 적용하였다. 강제 배출량은 화재안전기준과 기존 연구를 토대로 설정하였으며, 방화막과 프로시니움 (Proscenium) 벽 사이 간격은 0 m, 0.5 m인 경우를 대상으로 하였다. 방화막과 프로시니움 벽이 완벽하게 밀착되어 있는 경우, 강제 배연구와는 상관없이 객석으로의 연기 확산은 일어나지 않았다. 방화막과 프로시니움 벽 사이의 간격이 0.5 m인 경우, 방화막이 없는 경우에 비해 무대 공간 내에서 연기층이 더욱 낮은 높이까지 하강하였으며, 이는 방화막에 의해 객석으로의 연기 확산이 방해받았기 때문이다. 한편, 동일한 방화막 조건에서, 강제 배연구가 있는 경우가 없는 경우에 비해 방화막과 프로시니움 벽 사이 간격을 통한 유출 질량유량이 작았다. 본 연구를 통하여 방화막과 강제 배연구가 공연장 무대 화재 시 객석으로의 연기 확산을 억제할 수 있는 효과적인 방법임을 확인하였다.

• 한국안전학회지
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• 제38권6호
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• pp.9-15
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• 2023

Hydrogen is gaining attention as a sustainable and renewable energy source, potentially replacing fossil fuels. Its high diffusivity, wide flammable range, and low ignition energy make it prone to ignition even with minimal friction, potentially leading to fire and explosion risks. Workplaces manage ignition risks by classifying areas with explosive atmospheres. However, the effective installation of a blast wall can significantly limit the spread of hydrogen, thereby enhancing workplace safety. To optimize the wall installation of this barrier, we employed the response surface methodology (RSM), considering variables such as wall distance, height, and width. We performed 17 simulations using the Box-Behnken design, conducted using FLACS software. This process yielded two objective functions: explosion likelihood near the barrier and explosion overpressure affecting the blast wall. We successfully achieved the optimal solution using multi-objective optimization for these two functions. We validated the optimal solution through verification simulations to ensure reliability, maintaining a margin of error of 5%. We anticipated that this method would efficiently determine the most effective installation of a blast wall while enhancing workplace safety.

• 문화기술의 융합
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• 제10권2호
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• pp.531-536
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• 2024

최근 농업분야의 스마트 농기계로 분류되고 있는 방제드론은 농촌지역의 고령화 시대를 맞이하여 작업 시간 단축과 방제효과를 높이기 위해 하드웨어 및 소프트웨어를 결합하여 스마트 방제 및 자동방제 시스템 구축을 위해 노력하고 있다. 본 논문에서는 관리관제 및 자동방제 시스템 구축을 위한 기초연구로 방제드론 전용노즐의 특성을 분석하였다. 다양한 드론 모델의 종류, 방제사, 바람, 비행속도, 비행고도, 날씨 조건, UAV 농약 종류 등 다양한 변수를 고려하기 위해서는 노즐의 특성파악과 범용성을 고려하여 약제살포 기준 제시가 가능한 관련 연구가 필요하다. 따라서 다양한 변수 고려가 가능하도록 자체 설계노즐을 기반으로 유동해석(CFD) 시뮬레이션을 실시하고 감수지 실험을 통하여 액적분포의 이론값과 실험값을 비교 분석하였다. 추후 드론운용에 따른 다양한 변수를 고려하여 정확한 비산을 산출하고 관리관제 및 자동방제 시스템에 활용하고자 한다.

• 한국조경학회지
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• 제32권1호
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• pp.33-46
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• 2004

This study is aimed to redesign established parks and to propose a series of devices protecting them from vandalism. To solve the problems, we ascertained the damaged areas of the park greens. The trace analysis was performed to grasp the transverse inside the parks of Jeonju and Iksan in Collabuldo. Then, we presented the basic plan for minimizing park damage and for remodeling the system of movement. The results of the study are summarized as follows: it is identified that the transverse phenomenon is considerably wide-spread in majority of parks, and has no relationship to the park area or the green area. It is considered that the $\ulcorner$Condition rating class$\lrcorner$ of grass damage, which is grade 6, is extraordinarily high and the damage is accumulated considerably. Also, the damage part of other grade is discovered equally, and when unattended, the acceleration of damage is positive. A damage width a 0.5∼1.5m makes up the greater part of 79.6%. It also constitutes most of a rectilinear form. The difference in the height between the original point and destination point is below 0.7m, which is above 70%. It is identified that the interrelationship between the damage continuation length and plan distance is relatively high by the simple regression: analysis and by Pearson' correlation analysis. In spite of the normal damage continuation length is 20m, the frequency degree is downward with extreme point at 10m. Accordingly, it is assumed that park users have physical and psychological pressure when they cross the lawn field. Damage types are classified as the Simple cut cross type, the Behavioral facilitates type, Access advantage type and the Strolling type through type classification. It is considered that this classification is effective when identifying short pass type on lawn field according to the damage length and intensity.

• 대한기계학회논문집B
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• 제27권9호
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• pp.1299-1308
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• 2003

This paper is studied to investigate the effect of slits and swirl vanes on the development of turbulent flow fields in gun-type gas burner with a cone type baffle plate because this gas burner is generally composed of eight slits and swirl vanes. All of turbulent characteristics including mean velocities were measured in the horizontal plane and cross section by using X-type hot-wire probe from hot-wire anemometer system. This experiment is carried out at flow rate 450 l/min in the test section of subsonic wind tunnel. Slits cause the fast jets, and then they have the characteristic that the flow is not adequately spread to radial direction and has long flow length and very small flow velocity distribution in the central part. On the contrary, swirl vanes does not have long enough for adequate flow length to downstream because the rotational flow diffuses remarkably to radial direction. However, the suitable arrangement between slits and swirl vanes causes effective flow width and flow length, and then it promotes fast flow mixing over the entire region including central part to increase turbulence more largely and effectively. Therefore, it is thought as a very desirable design method in gun-type gas burner to locate slits on the outside of swirl vanes.

• 한국화재소방학회논문지
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• 제28권6호
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• pp.69-75
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• 2014

최근 발생한 아모레퍼시픽 창고화재는 국내 랙크식 창고의 자동식소화설비 및 감지기 설치기준의 보완 및 개선의 필요성을 제시하고 있다. 물류창고는 보관물품에 따라 화재 확산율 및 열 방출비율이 다르며 저장높이, 랙크 배치, 통로폭, 물품의 양 등에 따라서 화재위험성이 결정된다. 고천정화에 따른 화재하중의 증가로 인하여 자동식 스프링클러설비가 작동하여도 가연물에 직접적인 침투효과에 한계가 있으며 화재감지기의 작동시간이 지연되어 초기소화에 실패할 확률이 높아진다. 이를 위하여 본 연구에서는 화재사례 및 국내외 관련규정비교 그리고 현장조사 등을 수행하여 랙크식 창고의 초기소화 및 제어성능을 확보하기 위한 수용물품의 위험도 분류 및 스프링클러 설치기준 개선방향과 화재피해를 최소화하기 위한 제도적 도입을 제안한다.