Shock pressure of wave breaking on vertical wall is studied experimentally with beaches, which have four different slopes (1/4.02, 1/7.05, 1/10, 1 /13.5). This results is summerized as follows: 1. Maximum impact presures are occured where the wave break directly on the wall rather than breaking in front of the wall. 2. Deep water steepness, and the beach slope are the two Quantities governing the magnitude and location of maximum dimensionless impact pressure from wave breaking directly on the wall, also, the greatest pressure is produced with a beach slope of 1/10. 3. This study is clearly shown that the location of maximum pressure can be presented above still water level under respectively experimental condition. The dimensionless elevation of maximum Pressure is greatest on a beach slope of 1/10.

For the improvement of productivity of Pleurotus ostreatus, the production of liquid spawn was studied. The highest liquid spawn production was obtained after shaking culture for 4 days in the culture medium containing 5%(W/V) wheat flour, 0.2%(W/V) yeast extract, 0.1%(W/V)$KNO_3$ 0.05% (W/V) $MgSO_4{\cdot}7H_2O$, 0.05%(W/V) $KH_2PO_4$. The optimum pH and temperature was 7.0 ana $30^{\circ}C$. The period required to complete the mycelial growth after spawning were 28, 22, 10 and 9 days, respectively, when the 2%(V/V) of solid spawn and 2%(V/V), 5% (V/V) and 10%(V/V) of liquid spawn were inoculated. The days required from spawning to fruiting bodies were 38, 34, 28 and 27 days.

In this paper, the characteristics of electrical breakdown and TDDR (Time Dependant Dielectric Breakdown) were studied to evaluate stability and reliability of thin insulator films such as oxide and nitride. As the oxide film thickness decreased, the electrical breakdown field was increased proportioning to its reverse square root, ${d^{-\frac{1}{2}}}$. As for the temperature dependance of breakdown field, its field was inclined to decrease as temperature increased. It also showed that oxide charge (Qss) was changed by stress field and stress time. Consequently, TDDB characteristics and breakdown mechanism proved the improvement of reliability and stability and provided the accurate analysis to predict a device life time.

To predict the airloads on helicopter rotors in hover, the doublet panel method of the first order is applied. For this simulation, the rotor blade is divided into many panels both in spanwise and in chordwise direction, and Kocurek-Tangler's prescribed wake with roll-up process is taken for determing wake geometry and then represented by vortex lattice. To abtain more physically realistic calculation of induced velocity, the vortex core model is adopted and the compressibility effect is considered by Karman-Tsien rule.

탄소강 평활재 및 미소결함재를 사용하여, 미소 정류크랙의 크랙 개폐구거동의 상세한 관찰과 초기결함을 상정한 미소 원공과의 상호 한계크기의 비교 검토를 통하여, 다음과 같은 결론을 얻었다. 평활재의 정규크랙은, 피로과정중에 압축잔류응역이 크랙선단의 개구를 억제하는 것에 의하여 정류하게 되고, 그 크기는 평활재의 피로한도를 저하시키지 않은 미소 원공의 한계크기와 거의 일치하여, 두 경우가 역학적으로 거의 등가함을 시사해 주고 있다.

축의 지름이 구멍의 지름보다 큰 경우, 축을 구멍에 조립하는 작업이 용이 하도록 하는 방법을 연구하였다. 이 조립작업의 성능평가를 위한, 새로운 다중목적함수(多重目的函數)를 고안하고 그에 관련된 설계변수들의 최적값을 찾아보았다.

The intensity of ultrasound in liquid is calculated by improved analytic method. Helmholtz equation or Rayleigh's proposition does not offer the analytic solution. Considering a bounded medium, the use of the image source method in electromagnetic thoery gives a new way of calculating the total ultrasonic intensity in liquid. Some methods of measuring the intensities are also mentioned.

높은 전압으로 충전된 Capacitor를 순간적으로 원통형 coil에 방전하면 순간적으로 강한 전자장 impulse가 발생한다. 이때 coil를 둘러 싼 금속 tube는 radial 방향의 힘을 얻어 팽창한다. 본 논문은 이때 tube내의 전자장분포와 tube 벽의 움직임을 integral equation method를 사용하여 해석하였다.