The objective of this work is to investigate the A-IMS structural defects on the tubular shaft and solid shaft by analyzing the under-fill, metal flow, effective stress and load characteristics. The tubular shaft and solid shaft were designed 6 stage process by upper and lower die. The results were analysed by using a finite elements analysis method. The coefficient of frictions were set Oil_Cold conditions as referred to the analysis library. It was found that the actual under-fill phenomenon was not observed in both tubular and solid shaft. The load values of tubular and solid shaft were 520ton and 255ton, respectively. These values were under the limit of forging machine maximum value.

The objective of this study is to investigate the effect of closed and open type on the load characteristics and amount of waste in tubular shaft and solid shaft for optimal design. The open and closed type were designed by 6 stage processes and applied for analysis. The coefficient of friction was set to Oil_Cold conditions as refer to the analysis library. It is found that the actual underfill phenomenon was not observed on the closed and open type. The metal flow of the closed and open type are revealed that the folding phenomenon was not occurred, thus there is no problem in actual production. The load characteristics are similar from stage 1 to stage 3 due to the same geometry of upper and lower die. However, tubular shaft and solid shaft are decreased 26% and 32% load from stage 4 to stage 6. In case of open type, amount of waste of tubular shaft and solid shaft are 11g and 14g, respectively.

The objective of this study was to investigate the optimal design on the tubular shaft and solid shaft for A-IMS of commercial vehicle. The tubular shaft and the solid shaft were designed by 6 stage processes and the results were analyzed by using a finite element analysis method. The coefficient of friction was set to Oil_Cold conditions as referred to the analysis library. It was found that the actual underfill phenomenon was not observed on the tubular shaft and solid shaft. The metal flow of the tubular shaft and solid shaft revealed that the folding phenomenon was not occurred, so there is no problem in actual production. Principal stress and load characteristics of tubular shaft were higher than those of solid shaft since the tubular shaft has many deformation from stage 1 to stage 3.

In this study, the effect of slit length on the reduction of waste material was studied numerically. At the same time, the tightening axial force between steering shaft and asymmetry pinch yoke was also studied and compared. To achieve this study, the numerical simulation was performed by AFDEX commercial code. The slit length(Ls) of pinch yoke was increased from 25mm to 34mm by the steps with an interval of 3mm. AISI 1025 was applied for the source material of asymmetry pinch yoke. Amount of deformation was applied as much as 0.1mm for tightening the pinch bolt yoke and the steering gear shaft. It was revealed that the stress of steering shaft ear in XX-direction and YY-direction showed the highest value in 34mm and 31mm of slit length cases, respectively. The stress of ZZ-direction has the same value in all cases. The tightening stress between the asymmetry pinch yoke and the shaft of steering gear had the highest value in XY-direction. In additions, when slit length was increased by the steps with an interval of 3mm, the material was more wasted approximately as much as 0.844g. In conclusions, 31mm of lit length was the optimal length in aspect of the tightening stress and the waste material.

본 연구는 국가산림자원조사 자료를 이용하여 충남지역에 분포하는 사유림에 대한 포괄적인 개념의 산림경영율을 지역별, 임상별, 영급별, 경급별, 주요 수종별로 구분하여 분석하고자 하였다. 충청남도 사유림에서 조사된 제 5차 국가산림자원조사 자료 고정표본점은 총 971개소이며, 사유림 내에서 포괄적인 산림시업이 이루어진 고정표본점은 총 752개소로 나타났다. 본 연구 결과에 의하면, 충청남도 전체 사유림에 대한 포괄적인 산림경영율은 약 86.37%로 나타났다. 지역별 사유림에 대한 매년 연도별 산림 경영율은 공주시에서 14.07%로 가장 높은 경영율을 보였고 반면에 홍성군이 1.14%로 가장 낮은 경영율을 보였다. 임상별 산림경영율은 활엽수림에서 33.25%로 가장 높게 나타났으며, 반면에 혼효림에서 22.87%로 가장 낮게 나타났다. 영급은 3영급(33.77%)과 4영급(37.64%)에서 가장 높은 산림경영율로 나타났으며, 경급은 소경목(43.27%), 중경목(35.18%), 대경목(1.41%)으로 갈수록 산림경영율이 감소하는 경향을 보였다. 본 연구 결과는 충남지역에 분포하는 사유림의 포괄적인 사유림경영율에 대한 기초적인 정보를 제공할 수 있을 것으로 사료된다.

The objective of this study is to investigate the effect of operating conditions on the performance of small HSDI compression ignition engine. Combustion and exhaust emission characteristics of engine were studied by using CFD simulation with ECFM-3Z combustion model. The conditions of simulation were varied with injection timing, injection pressure, and operating speed, and the results were compared in terms of combustion pressure, rate of heat release, NOx and soot. It was found that as injection timing was advanced and injection pressure is increased, combustion pressure and rate of heat release were increased. As a result, NOx generation is increased. Soot generation is also increased due to the wall film caused by the increase of the injection pressure and locally the rich mixture caused by the effect of the advancing of injection timing.

In this study, the effect of upper die type on the load characteristics of lower die and the wasted material was studied numerically. The different shapes(A-type, B-type, and C-type) of upper die were applied. Also finite element analysis method was applied for the analysis in each stage. The half of X, Y plane was analyzed due to the symmetrical shape in order to reduce the analysis time and be accurate results. The coefficient of friction was set to oil_cold conditions as refer to the system library. It was revealed that principal stress was the order in A, C, and B. A and B type have the highest value in 4 stage, and C type shows the highest value in 3 stage. In addition, Von mises stress were higher in order A, B, and C. A and B type have the highest in 4 stage, and C type shows to have about the same value in the 2 - 5 stage. The load was generally higher than C type. The load of C type was reduced in YY-direction at each stage without 2, 5, 6 stage.

본 연구는 제주시험림 일대의 삼나무 임분을 대상으로 간곡선식을 추정하여 임목의 간재적표를 작성하였다. 조사대상지는 제주시험림 내 삼나무조림지에서 임분을 대표할 수 있는 표준지를 선정하여 직경이 골고루 분포하도록 총 20그루의 표본목을 공시목으로 사용하였다. 본 연구에서 간곡선식은 Kozak 모형을 이용하여 모수를 추정하였다. 추정된 모형의 적합성 지수는 99%, 오차는 0.008, 절대평균편차는 0.832로 나타났다. 본 연구에서 제시된 삼나무림 간재적표는 제주도 지역에 분포하고 있는 삼나무림의 합리적 경영을 위한 정보를 제공해 줄 것으로 사료된다.

In this study, the effect of upper die type on the load characteristics of lower die and the wasted material was studied numerically. The open and closed types of upper die were applied for each stage and the results are analyzed using a finite element analysis method. The half of x,y plane was analyzed due to the symmetrical shape in order to reduce the analysis time. The coefficient of friction was set to Soap_Cold conditions as refer to the analysis library. It was revealed that a lot of underfill portion was observed the open type in stage 4. As a result of the maximum and minimum values of the max principal stress, closed type case much receives compressive stress about 620MPa-2019MPa. In case of open type, The load was reduced in all direction at each stage

This experimental work was performed to reveal the effect of intake air temperature on the improvement of performance and exhaust emissions in a SI engine. To achieve this, fuel consumption rate, combustion pressure, rate of heat release, and reduction of exhaust emissions were measured and compared in 4-cylinder spark ignition engine. It was founded that lower intake air temperature can lead higher combustion pressure and heat release rate due to the higher intake air flow rate, volumetric efficiency, and fuel consumption rate. At the same time, higher intake air temperature leads to the longer ignition delay time, therefore, retarded ignition of engine was observed. Lower CO and HC values were also observed as the intake air temperature increases.

Injection rate characteristics of biodesel fuels according to the blending ratio was described in this work. The injection rate measuring system based on the Bosch's method was utilized to measure and compare the fuel injection rate characteristics. Three different types of biodiesel which were derived from seed, unpolished-rice, and soybean were blended with the diesel fuel in 20% and 40% of volumetric ratio. The fuel properties, injection mass, and injection rate characteristics were obtained and compared in various injection conditions. It is expected that this observations provide important insights into the effect of fuel properties on the biodiesel fuel injection rate performance in a CI engine

Numerical analysis of the electric vehicle battery was performed for the optimization of the thermal management under various operating conditions. For the analysis of internal flow and temperature distributions under the different operating conditions of battery, the battery system which was packed 18 battery cell with -25℃∼ 65℃ operating temperature range was considered, and the air flow rate, velocity, and ambient temperature conditions were varied and compared. It was revealed that the cooling system for battery was necessary to maintain its performance for hot ambient conditions. Especially, in this condition, at least 90m3/h of air flow rate are required to maintain the module temperature under 40℃. However, heating system of battery for cold ambient conditions doesn't need.

This analytical work was performed to reveal the effect of inlet geometry of battery pack on the temperature distributions and flow stream line for a electric vehicle. To achieve this, standard k-ε model with wall function was applied and the working conditions of battery pack under different air flow rate and inlet area according to the geometry were estimated. It was revealed that as inlet area was smaller, the flow velocity was faster, and it can't cover the whole area of battery module. In case of two inlet case, the cooling efficiency of air flow is less than that of one inlet case because of low flow rate.

This paper is designed a VSI X-CRL synthetic control chart in aspect of economy. We found the optimal sampling interval and various control limit factors under various cost parameters using cost function, proposed Lorenzen and Vance. Optimal design parame

This paper presents a economic design of synthetic control chart that is an VSI(variable samlping interval) X control chart and conforming run length chart. Computer simulation is carried out for comparing performance of developed control chart with X-CRM synthetic chart. We found that optimal parameter of suggested chart for minimize quality cost. And then a comparison and analysis between synthetic VSI X-CRL chart and X-CRM synthetic chart in the economic aspect. Then VSI X-CRL chart consistently produces smaller quality cost than X-CRM synthetic chart.

Statistical process cintrol is intended to assist operators of a stable system in monitoring whether a change has occurred in the process, and it uses several control charts as main tools. In design and use of control chart, it is rational that probabilit

In this study, we establish bootstrap control limits for robust M-estimator chart by applying the bootstrap method, called resampling, which could not demand assumptions about pre-distribution when the process is skewed and/or the normality assumption is doubt. The results obtained in this study are summarized as follows : bootstrap M-estimator control chart is developed for applying bootstrap method to M-estimator chart, which is more robust to keep Type Ⅰ error when process contain contaminate quality characteristic.