• Journal of Biosystems Engineering
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• 제18권4호
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• pp.351-357
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• 1993

Recently, a garlic peeler with high performance is being demanded due to increase of consumption of peeled garlic. Although the air type out of various types of garlic peelers is recommended to remove effectively skin of garlic, it has an important problem of large energy consumption. This study was performed to analyze performance of an air-type garlic peeler for its optimum design. Performance indices to represent performance of garlic peeler include peeling ratio, energy efficiency and peeling performance. The factors such as aperture of nozzle, angle and position of air injection, charge rate of garlic, peeling time and so on must be considered to design optimally an air-type garlic peeler.

• 한국추진공학회지
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• 제20권6호
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• pp.18-28
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• 2016

듀얼 벨 노즐을 평가하기 위한 기초연구로써 전산수치해석을 진행하였다. 추후 진행할 설계 변수 연구를 위해 듀얼 벨 노즐을 설계하고 입구 조건과 난류 모델, 최적 격자수를 선정하였다. 듀얼 벨 노즐은 KSLV-II 1단 노즐을 기반으로 설계하였다. 입구 조건은 설계 값과의 비교를 통해 비반응 8화학종의 동결유동 모델로 결정하였다. 난류 모델은 SST $k-{\omega}$ 모델이 가장 적합하였다. 격자 민감도 해석을 통해 약 15만개의 최적 격자수를 선정하였다. 본 연구에서 결정한 내용들을 바탕으로 향후 한국형발사체에 듀얼 벨 노즐을 적용한 해석을 진행하여 성능 이득을 연구하고자 한다.

• 대한조선학회논문집
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• 제60권6호
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• pp.424-432
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• 2023

This study deals with the design of a safety device around a leisure boat propeller. The safety device is to be designed to minimize performance degradation attached to propulsors in coastal waters. These devices, important for preventing propeller accidents, negatively gives influence boat performance, especially at higher speeds. In order to minimize the negative effect, the accelerating ducts, normally used in ESDs (Energy Saving Devices) have been chosen as a safety device. The present study aims to design an optimal duct (minimizing negative effect) through the parametric study. Based on the Marine 19A nozzle, the nozzle's thickness and angle were varied to obtain the optimum parameter in the preliminary design by the computational fluid dynamics program Star-CCM+ Ver. 15.02. In the detailed design, a NACA 4-digit Airfoil shape resembling the Marine 19A by modification at the trailing edge was chosen and the optimum shape was chosen according to variation of camber, thickness, and incidence angle for optimization. The optimally designed duct shows a speed decrease of about 10% in the sea trial result, which is much smaller than the normal speed decrease of at least 30%. The present designing method can give wide applications to the leisure boat because the wake is almost the same due to using the outboard propulsor.

• 한국환경과학회지
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• 제30권5호
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• pp.399-406
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• 2021

The dissolution of ionized gas in dielectric barrier plasma, similar to the principle of ozone generation, is a major performance-affecting factor. In this study, the plasma gas dissolving performance of a gas mixing-circulation plasma process was evaluated using an experimental design methodology. The plasma reaction is a function of four parameters [electric current (X₁), gas flow rate (X₂), liquid flow rate (X₃) and reaction time (X₄)] modeled by the Box-Behnken design. RNO (N, N-Dimethyl-4-nitrosoaniline), an indictor of OH radical formation, was evaluated using a quadratic response surface model. The model prediction equation derived for RNO degradation was shown as a second-order polynomial. By pooling the terms with poor explanatory power as error terms and performing ANOVA, results showed high significance, with an adjusted R² value of 0.9386; this indicate that the model adequately satisfies the polynomial fit. For the RNO degradation, the measured value and the predicted values by the model equation agreed relatively well. The optimum current, gas flow rate, liquid flow rate and reaction time were obtained for the highest desirability for RNO degradation at 0.21 A, 2.65 L/min, 0.75 L/min and 6.5 min, respectively.

• 대한기계학회논문집B
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• 제28권4호
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• pp.389-394
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• 2004

An experimental study on the NOx formation of LNG flame in fuel staged combustor has been studied. The design concept of multi fuel/air staged combustor is creation of two separate flame, a primary flame is a act as a pilot flame for the secondary combustion stage combustion zone, where most of fuel bums. Experiments were performed on a semi-industrial scale (thermal input 0.233 MW) in a laboratory furnace and Liquefied Natural Gas(LNG) was used as a primary and secondary fuels. This study included parametric study to identify the optimum operating conditions which are primary/secondary fuel ratio, and primary/secondary air ratio for reducing NOx emission with two types of nozzle. The test demonstrated that NOx emission can be reduced by >70% in accordance with operating conditions.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 추계학술대회논문집B
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• pp.161-166
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• 2001

An Experimental study on the NOx formation of LNG flame in fuel staged combustor has been studied. The design concept of multi fuel/air staged combustor is creation of two separate flame, a primary flame is act as a pilot flame for the secondary combustion stage combustion zone, where most of fuel burns. Experiments were performed on a semi-industrial scale (thermal input 0.233 MW) in a laboratory furnace and Liquefied Natural Gas(LNG) was used as primary and secondary fuels. The study included parametric study to identify the optimum operating conditions which are primary/secondary fuel ratio, and primary/secondary air ratio for reducing NOx emission with two types of nozzle. The test demonstrated that NOx emission can be reduced by >70% in accordance with operating conditions.

• 대한기계학회논문집B
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• 제23권6호
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• pp.761-768
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• 1999

This paper is studied to find the optimum condition of double-inlet Sirocco fan installed in an indoor PAC for low noise operation by the Taguchi method. The goal of this study is to obtain the best combination of each control factor which results in a desired flowrate of Sirocco fan with minimum variability. In this study, the parameter design of the Taguchi method is adopted for robust design by the dynamic characteristic analysis using orthogonal arrays and S/N ratios. The flowrate measurements are conducted by using a multiple-nozzle-type fan tester according to the orthogonal array L9($3^4$). The results of this study can be summarized as follows ; (i) The optimum condition of control factor is a set of where A is an inner to outer diameter ratio($D_1/D_2$), B is a width to outer diameter ratio($L/D_2$), C is a blade attachment angle(${\theta}$) and D is a number of blade(Z), (ii) The flowrate under the optimum condition satisfies the equation $y=0.0384{\cdot}M$ where M is a signal factor, namely number of revolution. The flowrate performance improves about 7.3% more largely as compared with the current condition, which results in about 35RPM reduction of number of revolution for the target flowrate $18.5m^3/min$, and (iii) The sensitivity analysis shows that the major factors in contribution to flowrate performance are A, B, and D ; the percentage contributions of each control factor are 44.01%(Z), 26.77%($D_1/D_2$) and 20.42%($L/D_2$).

• 한국분무공학회지
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• 제21권4호
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• pp.195-199
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• 2016

Spraying of nozzles and design of tractor-attached boom sprayers have been studied for analysis of liquid spraying features. The following conclusions have been drawn. At all pressures, twin flat spray tips was finer than flat spray tips. A fine spray with VMD of 101 to 200 appeared at 1.5MPa. So, it was selected as the boom sprayer nozzle. In spraying uniformity analysis, Type B was proven to have more uniformity than Type A and Type C at 52.0 cm attached distance. Type A and Type C were proven to have more uniformity than Type B at 58.5 cm attached distance. It is concluded that these results reflect atomizing characteristics of nozzles during pest control with tractor-attached boom sprayer. Therefore, optimum setting will be putting Type C with 58.5 cm distance.

• Journal of Welding and Joining
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• 제33권2호
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• pp.40-46
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• 2015

This study was performed to investigate the effect of ultrasonic nano crystal surface modification (UNSM) on residual stress mitigation after Weld Inlay repair for butt dissimilar metal weld with Alloy 82/182 in reactor vessel In/Outlet nozzle. As-welded and Weld Inlay specimens were made in accordance with design standard of ASME Code Case N-766, and two planes of their weld specimens were peened by the optimum UNSM process condition. Peening characteristics for weld specimens after UNSM treatment were evaluated by surface roughness and Vickers hardness test. And, residual stress for weld specimens developed from before and after UNSM treatment was measured and evaluated by instrumented indentation technique. Consequently, it was revealed that the mitigation of residual stress in weld metal after Weld Inlay repair of reactor vessel In/Outlet nozzle could be possible through UNSM treatment.

• 한국추진공학회지
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• 제9권1호
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• pp.1-8
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• 2005

설계단계에서 수행되는 액체로켓엔진의 추력실 형상설계와 성능예측을 위하여 화학평형을 고려한 축대칭 압축성 해석코드를 개발하였다. 사용자의 편리함과 효율성에 중점을 두었으며, 형상파라미터의 입력값에 따라 자동으로 격자를 생성하고 연소실 조건은 추진제 조합, 연소압 그리고 혼합비를 지정함으로서 내부에서 계산하게 된다. 따라서 설계자는 추력실 형상 및 작동조건을 변화시켜 각각의 설계변수가 추력성능에 미치는 영향을 빠르고 손쉽게 파악할 수 있도록 하였다. CEA의 결과, JPL 노즐의 실험결과, 두 종류의 LRE 실제 엔진 자료, 그리고 KSR-III의 설계점 및 탈설계점 연소시험결과와 비교함으로서, 다양한 측면에서 해석코드의 정확도와 적용성을 평가하였다.