부산항내는 시간당 10척 이상의 선박이 통항하고 있고, 일본 왕복 제트포일 여객선이 30 kts 40 kts의 고속으로 항행하고 있어 우리나라에서도 고밀도 교통해역으로 간주된다. 더불어 이 항로 내에서는 제트포일 선박의 약 18 %가 고속으로 추월을 하거나 항로 밖으로 이탈하여 운항하고 있어 타 선박과 빈번히 조우하거나 항로 밖 항행 등과 같은 현행 법령을 미준수하고 있는 것으로 10일간의 해상교통조사를 통하여 분석되었다. 이 논문에서는 부산항의 교통조사 결과를 기반으로 한 해상교통류 시뮬레이션을 통하여 부산항내의 제트포일 여객선의 운항자 허용 가능 속력이 약32노트 이하로 계산되었으며, 제트포일 선박이 항로 내 및 항로 밖으로 통항하는 경우의 조선부담감 발생비율 차이가 미미한 것으로 분석되었다. 또한 시간당 통항척수가 감소함으로써 조선부담감이 다수 감소하기 때문에 피크타임 시간대 운항을 피하여 통항안전을 확보하여야 할 것이다.

A cooling system that applies impinging jet is studied. To create a jet, a square edge type nozzle is used as its shape. The impinging jet that composes a cooling system which applies impinging jet is created in the nozzle plate that correspond to each LED where the cooling area exists. The distance(d) between the nozzle plate and LED plate with heat sink is where the LED light is established. The main variation and the standard is examined for four different cases through the way out diameter of nozzle plate exit(D). The examined velocity distribution and temperature distribution about the impinging jet cooling system consisted of nozzle plate. It was found that an individual LED consisting of nozzle plate was efficient.

코로나방전플라즈마제트(CDPJ) 생성장치를 제작하여 조업특성을 조사하고 비가열살균기술로서의 활용가능성을 탐색하고자 E. coli를 대상으로 살균성능을 조사하였다. CDPJ장치는 전력공급장치, 변압기, 전극, 송풍기, 시료처리부 등 다섯 부분으로 구성하였다. 전압 10.0-20.0 kV의 직류전기를 10.0-45.0 kHz 구형파 펄스형태로 텅스텐리드 전극에 투입함으로써 코로나방전 플라즈마를 생성하고 동시에 전극사이로 강한 공기를 주입함으로써 하부방향으로 토출하는 플라즈마제트를 생성하였다. CDPJ 처리는 플라즈마 토출구 하부에 처리대상 물체를 위치하고 일정시간 처리하는 방식으로 시행하였다. 주파수를 높일수록 다량의 전류가 유입되었고, 비례하여 전력소비량도 증가하였다. 플라즈마 생성을 위한 임계전류는 1.0 A, 임계주파수는 32.5 kHz이었으며, 1.5 A 이상 40.0 kHz 이상에서 안정적인 플라즈마제트가 생성되었다. 플라즈마제트의 길이는 전류에 따라 증가하였고, 2분 이하 처리 시 대상물체의 표면온도 상승은 25oC를 하회하였다. E. coli 살균력은 전류세기에 비례하여 증가하였고, 전류 1.5 A에서 1분간 CDPJ처리에 의해 4.5 log 이상의 살균효과를 보였으며, 살균패턴은 2단계 1차 반응으로 확인되었다.

This paper investigates the downwash effect of a rooftop structure (RTS) representing a typical RTS with jet diffusion. The effect of rooftop structure height on the severity of the downwash effect is assessed. As a result, design guidance provided for determining structure height required to avoid the downwash effect.

A cooling system that applies double collision jet is studied. To create a jet, a square edge type nozzle is used as its shape. The impinging jet that composes a cooling system which applies double impinging jet is created in the single nozzle and double nozzle that correspond to each LED where the cooling zone exists. The distance between the 2nd nozzle and LED with heat sink is where the LED package is established. The main variation and the standard is examined for four different cases through the way out diameter of 1st nozzle. The examined velocity distribution and temperature distribution about the cooling system consisted of single and double nozzle. It was found that an individual LED consisting of double nozzle was efficient.

In this review article the famous 'jet equation' in a Minkowski magnetosphere around the compact objects will be fully derived for the pedagogical purposes.

In this review article the famous 'jet equation' of the neutron stars and black holes will be fully derived for the pedagogical purposes.

We have developed a cylindrical mixing layer model of a stellar jet including cooling effect in order to understand an optical emission mechanism along collimated high velocity stellar jets associated with young stellar objects. The cylindrical results have been calculated to be the same as the 2D ones presented by Canto & Raga(1991) because the entrainment efficiency in our cylindrical model has been obtained to be the same value as the 2D model has given. We have discussed the morphological and physical characteristics of the mixing layers by the cooling effect. As the jet Mach number increases, the initial temperature of the mixing layer goes high because the kinetic energy of the jet partly converts to the thermal energy of the mixing layer. The initial cooling of the mixing layer is very severe, changing its outer boundary radius. A subsequent change becomes adiabatic. The number of the Mach disks in the stellar jet and the total radiative luminosity of the mixing layer, based on our cylindrical calculation, have quite agreed with the observations.

The interaction of an isotropic stellar wind with a stratified environment leads to collimate the stellar wind outflow, forming a narrow jet especially in non-adiabatic cases. A jet opening angle, i.e, a jet collimation increases with a jet cooling, in which a free-free radio continuum is dominantly contributed. After a qualitative comparison of the theoretically derived jet boundaries with the optically observed ones have been carried out in order to know the physical parameters of the observed ones as well as to study the jet dynamical interaction with the surrounding medium. Instead of the morphological jet boundary fitting, the free-free radio continuum shapes have been suggested and recalculated.