Most domestic pilots are trained at local airfields using propeller aircraft. Training aircraft are mainly trained in the airspace around the aerodrome, and mainly take-off and landing exercises that require a lot of practice among flight control skills. Aircraft noise is a sound that humans do not want. In this study, based on the Rotax 914 engine used in Korea, the propeller blade angle was changed by 1 degree for the 3-leaf “K company” propeller and the 3-leaf GSC wooden propeller, and the engine RPM was changed to examine the noise and thrust changes. The purpose of this study is to check whether noise and thrust loss are the least at the engine's maximum RPM, and to propose an aircraft operation plan in the noisy aerodrome area based on the values.

The emergency diesel generator of a nuclear power plant is a emergency AC power source that starts up within 10 seconds when a LOOP(Loss Of Off-site Power) occurs and supplies power to essential safety facilities. In this study, factors affecting start signal input time, engine rotation start time, 30% of engine rated speed, 80% of engine rated speed were studied to secure starting reliability. As a result, it was found that the section before the 30% of engine rated speed was affected by the mechanical management status from the start signal to the fuel oil linkage system. After the 30% of engine rated speed section, it was the maximum fuel supply section, and the time reduction effect through management improvement was insignificant.

In this study, we analysed the influence of the flow and performance of the generated micro gas turbine with different rotational speeds. CFD analysis was also performed using commercial code called ANSYS CFX 14.5. It adopted the turbine of radial flow type suitable for power generation for small rotating equipment. The number of blades was designed with each radial turbine 8, vane nozzle 14. The boundary layer flow analysis was widely used to the SST model. Mass flow rate of the turbine was 1.45 kg/s. While the rpm varies from 38,000rpm to 48,000rpm under various boundary conditions, the distributions of Mach number and pressure were numerically analyzed for electric power output, turbine isentropic efficiency. We analyze the inlet pressure, outlet temperature, electric power output, turbine isentropic efficiency. It compared maximum and minimum revolution through CFD analysis. Power output of maximum revolution has been increased 18% more than minimum revolution. Isentropic efficiency of maximum revolution has been increased 16.5% more than minimum revolution. Therefore, maximum power output was 332kW, amaximum isentropic efficiency was 33.2%.

인터넷이 상품거래의 새로운 공간으로 등장한 것은 이미 오래 전의 일이고, 최근 일부 분야는 오 히려 오프라인 시장 보다 온라인 시장이 상품거래 의 주된 무대가 되고 있다. 종래부터 제조업자는 자 신이 제조한 상품이 유통업자에 의해 다시 판매될 경우에 적용되는 이른바 재판매가격에 대하여 일 정한 제한을 가하려는 시도를 해왔고, 이러한 재판 매가격유지행위(RPM)에 대하여는 공정거래법에 의해 일정한 규제가 이루어져 왔다. 이러한 현상은 인터넷 상거래의 경우에도 동일하게 발생할 수 있 고 실제로 미국에서는 이른바 인터넷최소광고가격 통제행위(IMAP)를 어떻게 취급할 것인지에 대한 논의가 한창 이루어지고 있다. 우리 공정거래법은 수직적 경쟁제한행위 중 가 격제한행위와 비가격제한행위를 각각 다르게 규율 하고 있고, 위 인터넷최소광고가격통제행위는 표 면적으로는 광고에 대한 제한으로서 비가격적 제 한행위의 성격을 가지지만, 실질적으로는 가격에 영향을 미치는 특성이 존재하는바, 이 논문에서는 우리 법상 이를 어떻게 취급할 것인지에 대하여 다 루어 보고자 한다. 논의에 앞서 재판매가격유지행 위와 관련한 기존의 당연위법의 원칙과 최근 미국 연방대법원 및 우리 대법원판결에 의해 제시된 합 리의 원칙에 관하여 살피기로 한다.

PURPOSES : The purpose of this study is to eliminate the noise of the vehicle after measuring the friction noise obtained from the NCPX (Noble Close ProXimity) method. The pure friction noise between the tire and road pavement could be determined from filtering the compositeness of sound and the influence of the vehicle noise. METHODS: The noise magnitude could be determined by analyzing the sound pressure level (SPL) and sound power level (PWL) along with the noise frequency of a FFT (Fast Fourier Transform) analysis as well as CPB (Constant Percentage Bandwidth) analysis. RESULTS: When the test for measuring the friction noise originated somewhere between tire and road pavement is performed with NCPX method, it must be fulfilled by attaching the surface microphone near the tire. In this condition, the surface microphone can measure the friction noise occurred at between tire and pavement, the chassis noise from the engine and power transfer units, the fluctuating aerodynamic noise, and the turbulence noise directly affected to the surface microphone. By using the NCPX method, the noise occurred at the vehicle must be eliminated for measuring the friction noise between tire and pavement from the traffic noise. CONCLUSIONS: The vehicle's testing engine noise depends on the vehicle and road types. The effect of vehicle's engine noise is less than the friction noise occurred at between tire and pavement at less than 1% effect.

The agitator with a reducer are usually using on the process of a water treatment. However, working the reducer at the field, a lubricant oil can leak out. It causes an environment pollution and a water service/sewerage pollution problem. In this study, the reducer with a drywell structure is developed in order to prevent the oil leakage. The drywell structure is that the reducer bottom housing and the support column of an output shaft are united, and taper roller bearings are in the bottom housing. During the development of the reducer, a mockup and a prototype are made by using CAD and a high speed CNC machine. Then, to prove the performance of the prototype, the performance tests, unload working test and the mechanical torque efficiency test, are conducted by the torque meter device. Also a motor velocity(rpm) control system is developed by a PID control according to the working loads(MLSS data). The results of the test are shown that the maximum torque efficiency is 88.45%, the oil leakage and the abnormal noise do not occur during the work. Therefore the reducer with the drywell structure and the motor rpm PID control system is successfully developed.

Sintered oilless bearing using fluid-dynamic mechanism for high revolution of over 10,000 rpm was developed by Powder metallurgy Process. Developed bearing was composed of Fe-40-60%Cu of which inner face consisted of six-regular-prominence-and-depression. Inner face has controlled pore size and amount according to application. Jitter and friction properties were tested under assembled conditions with housing and motor. Bearing-own properties and precision were also tested because of demanding for assembled properties. Measurement-skill as well as mould-production-skill were investigated for the precision of bearing. Final precision reached 2 in inner diameter tolerance and 5 in coaxiality under assembled conditions.