• Journal of the Korean Society of Propulsion Engineers
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• v.6 no.2
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• pp.53-63
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• 2002

The steady-state and transient performance simulation program for a turboprop engine(PT6A-62) was developed. Specially this program included some algorithms, such as flat-rated behaviors in performance and limit control algorithms to prevent the compressor surge and the compressor-turbine inlet limit temperature overshoot. In order to minimize analysis errors, on interpolation method in component characteristics using matching errors and specific heat and specific heat ratio, which are functions of temperatures were used. The developed steady state performance analysis program can handle various conditions such as altitude, bleed extraction, inlet temperature and pressure and part throttle, and the transient performance analysis program incorporated a general mode for transient simulation and a control mode for prevention of the compressor surge and the turbine inlet limit temperature overshoot.

• The Journal of the Korea institute of electronic communication sciences
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• v.13 no.5
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• pp.1071-1078
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• 2018

In this paper, we implemented community driving system for auto-vehicles as a preceding research of drone's community flight. We used ultrasonic sensors in order to measure the distance between vehicles, and designed each vehicles to maintain specific distance to each other, by making the following vehicle to stop moving when the distance is closed to less than 20cm, to start moving when the distance increases to more than 30cm. We have also designed vehicle to accelerate until the distance is closed to 30cm when they are apart for more than 40cm due to contingencies during driving.

• Journal of Astronomy and Space Sciences
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• v.19 no.4
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• pp.293-304
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• 2002

This paper describes the re-design and the calibration results of the MAG digital circuit onboard the KSR-3. We enhanced the sampling rate of magnetometer data. Also, we reduced noise and increased authoritativeness of data. We could confirm that AIM resolution was decreased less than InT of analog calibration by a digital calibration of magnetometer. Therefore, we used numerical-program to correct this problem. As a result, we could calculate correction and error of data. These corrections will be applied to magnetometer data after the launch of KSR-3.

• Aerospace Engineering and Technology
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• v.7 no.1
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• pp.91-98
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• 2008

Since the 1st space race between the United States and Soviet Union during the 1960s, we are competing 2nd space race to occupy the Lunar territory. Since the United States announced to construct the Lunar Base by the end of 2020, ED, Japan, and China launched Lunar explorers successfully. Even India is planning to launch a Lunar explorer in 2008. Korean government also announced that the Korea will launch first Lunar explorer in 2020. In this research Lunar mission trajectory design which will be fundamental data for Lunar mission with variable low thrust and Lunar mission trajectory which has a similar mission specification to SMART-1 are presented.

• Journal of the Korean Society of Propulsion Engineers
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• v.23 no.5
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• pp.60-66
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• 2019

In this report, the process characteristic(viscosity), mechanical properties, combustion characteristics, ground and flight test results of propellants used for a rocket-assisted projectile are described according to several aluminum contents. As the aluminum content increased, initial viscosity decreased, viscosity build-up accelerated, and combustion rate and pressure exponent decreased. In the ground fire test, the total impulse of the rocket-assisted projectiles containing 10 wt% of aluminum were 5% higher than that of the rocket-assisted projectiles containing 2 wt% and 18 wt% of aluminum. The motor efficiency compared to the theoretical performance was 85.6% with 18 wt% of aluminum, the lowest value among the propellant compositions.

• Journal of the Korean Society of Propulsion Engineers
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• v.17 no.4
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• pp.73-80
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• 2013

Endothermic fuel utilizing technology is considered as a unique practical method of hypersonic vehicle for long distance flight. Research activities about characteristics of fuel injection and combustion using cracked by endothermic reaction are reviewed. Studies on characterization of supercritical fuel injection and mixing within supersonic flow field are surveyed. Researches on combustion characteristics such as ignition delay time, laminar burning velocity and combustion efficiency at supersonic model combustor are reviewed. In addition, domestic research activities on endothermic fuel are surveyed.

• Nuclear Engineering and Technology
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• v.4 no.2
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• pp.116-131
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• 1972

A fast neutron time-of-flight spectrometer has been constructed with suitable choice of target thickness and proton bombarding energy in Li$^{7}$ (p, n) Be$^{7}$ nuclear reaction for a continuous keV spectrum of neutrons at 0 degree in 1-nsec pulse from a Van do Graaff and a time-pick-up fast neutron detector assembled with a 5 mm-thick 92% enriched B$^{10}$ slab and four heavily shielded 4＂$\times$3＂ NaI scintillation detectors. Energy resolution of this spectrometer is better than 0.3% at 50 keV and the signal-to-background ratio is also improved. Total cross section measurements of several separated single isotopes have been carried out with this spectrometer and analyzed by Rmaxtrix multi-level computer code. The spin values and resonance parameters of each individual resonances are given.

• Journal of the Korean Society of Propulsion Engineers
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• v.25 no.4
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• pp.1-11
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• 2021

To develop technologies for the stable operation of electric propulsion systems, the exhaust plume behavior of electric thrusters was studied using PIC-DSMC(particle-in-cell and direct simulation Monte Carlo). For the numerical analysis, the Simple Electron Fluid Model using Boltzmann relation was employed, and the charge and momentum exchanges due to atom-ion collisions were considered. The results of this study agreed with the plasma potentials measured experimentally. Near the thruster exit, active collisions among particles and charge exchanges created slow ions and fast atoms, which were expected to significantly affect the trajectory and velocity of the thruster exhaust plume.

• 한국벤처창업학회:학술대회논문집
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• 2023.04a
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• pp.67-71
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• 2023

인간은 출생부터 필연적으로 부모와 관계 속에서 다양한 경험을 통해 성장하고 발전하게 된다. 자녀가 세상에 태어나면서 부모와 언어적, 비언어적 의사소통을 통해 다양한 관계를 경험하면서 성장하고 발전하면서, 본인의 가치관 정립과 대인관계 형성을 위한 기초가 된다. 부모-자녀 간 원활하지 못한 의사소통이 자녀에게 정신건강 문제와 이탈, 비행과 범죄로 연결된다는 것을 많은 연구 사례가 볼 수가 있다. 이러한 선행연구를 살펴보면서 부모와 자녀 간의 원활한 개방적 의사소통이 자녀의 성장과 대인관계 형성을 하는 데 중요한 역할을 하지만, 원활하지 못한 의사소통이 이루어지면은 발전과 성장에 많은 문제를 가지고 청소년기를 보내고, 성인이 되어서도 건강하지 못 할 수가 있다. 본 연구의 목적은 중기 청소년의 성장 과정에서 자기 통제력 향상에 부모와 자녀의 개방적 의사소통이 원활할 때 중기 청소년의 발달과 성장에 영향을 줄 수 있는 자기 통제력에 대해 부모-자녀 간 개방적 의사소통의 매개 역할을 하는지를 검증하는 데 있다. 부모-자녀 간 메시지 전달이 감정교류 및 정보전달 등을 모두 포함하는 상호작용을 통해 성장과 발전을 할 수 있다는 것을 알 수 있다. 중기 청소년의 부모-자녀 간 원활한 의사소통에 영향을 미칠 수 있는 자기 통제력을 종속변수로 설정하여 본 연구를 검증하기 위해 진행하였다.

• Korean Journal of Applied Biomechanics
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• v.18 no.3
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• pp.61-69
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• 2008

The purpose of this study is to examine the success or failure on the balance beam in element group requirements posture which is bending salto side-ward tucked through kinetic analysis. The national team players were participated. The goal was to present training methods to coaches and athletes so as to provide scientifically useful information. The results from this study were summarized as below. When the performance was successful, the features of the body's center of gravity during the side somersault motion showed to spread from the center of the balance beam and the center of the gravity moved to the direction of the body's rotation. In the spring sections - event2 and 3, when the performance was successful, up/down fluctuation became more wider and increased air time. It supported the result that the projecting variable was higher than in failure trial. In addition, the right side hip joint angles and speed, and angular velocity as jumping up for a leap were larger than in failure trial. Those variables showed the optimal conditions for a leap. By increasing the speed of the upper limb from the shoulder and the speed of the shoulder joint angular velocity, the momentum was increased. Especially the right side shoulder joint angular velocity increased dramatically because the right leg was held. As to the side somersault motion, the angular momentum of successful trial with respect to x-axis was bigger than failed trial. It indicated that the increasing angular momentum with respect to x-axis was an important factor in flying motion. Besides, as to side somersault, the appropriate proportion of angular momentum with respect to y-axis and z-axis was a key to successful trails.