• Bulletin of the Korean Chemical Society
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• 제16권6호
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• pp.547-552
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• 1995

As an extension to the Kramers' restricted Hartree-Fock (KRHF) method [J. Comp. Chem., 13, 595 (1992)], we have implemented the Kramers' restricted configuration interaction (KRCI) program in order to calculate excited states as well as the ground state of polyatomic molecules containing heavy atoms. This KRCI is based on determinants composed of the two-component molecular spinors which are generated from KRHF calculations. The Hamiltonian employed in the KRHF and KRCI methods contains most of all the important relativistic effects including spin-orbit terms through the use of relativistic effective core potentials (REP). The present program which is limited to a small configuration space has been tested for a few atoms and molecules. Excitation energies of the group 14 and 16 elements calculated using the present KRCI program are in good accordance with the spectroscopic data. Calculated excitation energies for many Rydberg states of K and Cs indicate that spin-orbit terms in the REP, which are derived for the ground state, are also reliable for the description of highly excited states. The electronic states of the polyatomic molecule CH3I are probed from the molecular region to the dissociation limit. Test calculations demonstrate that the present KRCI is a useful method for the description of potential energy surface of polyatomic molecules containing heavy atoms.

• Journal of Audiology & Otology
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• 제23권4호
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• pp.197-203
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• 2019

Background and Objectives: Many studies have reported no benefit of sound localization, but improved speech understanding in noise after treating patients with single-sided deafness (SSD). Furthermore, their performances provided a large individual difference. The present study aimed to measure the ability of speech perception and gap detection in noise for the SSD patients to better understand their hearing nature. Subjects and Methods: Nine SSD patients with different onset and period of hearing deprivation and 20 young adults with normal hearing and simulated conductive hearing loss as the control groups conducted speech perception in noise (SPIN) and Gap-In-Noise (GIN) tests. The SPIN test asked how many presented sentences were understood at the +5 and -5 dB signal-to-noise ratio. The GIN test was asked to find the shortest gap in white noise with different lengths in the gap. Results: Compared to the groups with normal hearing and simulated instant hearing loss, the SSD group showed much poor performance in both SPIN and GIN tests while supporting central auditory plasticity of the SSD patients. Rather than a longer period of deafness, the large individual variance indicated that the congenital SSD patients showed better performance than the acquired SSD patients in two measurements. Conclusions: The results suggested that comprehensive assessments should be implemented before any treatment of the SSD patient considering their onset time and etiology, although these findings need to be generalized with a large sample size.

• 대한청각학회지
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• 제23권4호
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• pp.197-203
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• 2019

Background and Objectives: Many studies have reported no benefit of sound localization, but improved speech understanding in noise after treating patients with single-sided deafness (SSD). Furthermore, their performances provided a large individual difference. The present study aimed to measure the ability of speech perception and gap detection in noise for the SSD patients to better understand their hearing nature. Subjects and Methods: Nine SSD patients with different onset and period of hearing deprivation and 20 young adults with normal hearing and simulated conductive hearing loss as the control groups conducted speech perception in noise (SPIN) and Gap-In-Noise (GIN) tests. The SPIN test asked how many presented sentences were understood at the +5 and -5 dB signal-to-noise ratio. The GIN test was asked to find the shortest gap in white noise with different lengths in the gap. Results: Compared to the groups with normal hearing and simulated instant hearing loss, the SSD group showed much poor performance in both SPIN and GIN tests while supporting central auditory plasticity of the SSD patients. Rather than a longer period of deafness, the large individual variance indicated that the congenital SSD patients showed better performance than the acquired SSD patients in two measurements. Conclusions: The results suggested that comprehensive assessments should be implemented before any treatment of the SSD patient considering their onset time and etiology, although these findings need to be generalized with a large sample size.

• 한국항공운항학회지
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• 제2권
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• pp.23-45
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• 1994

본 연구 논문은 항공기 개발에 있어서 비행시험의 최종 단계라 할 수 있는 스핀시험의 정의, 스핀 시험방법 및 스핀 진입시의 회복방법과 실제 비행에서의 스핀 특성으로 스핀에 대한 안전성 제고 및 비행시험의 중요성을 논하였다.

• 대한전자공학회논문지
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• 제18권1호
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• pp.51-56
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• 1981

양호한 특성의 I2L 구조를 구현하기 위한 새로운 공정을 제안하였다. 이 구조에서는, extrinsic base 의 불순물 농도가 높으며, 또한 collector는 불순물 농도가 낮은 intrinsic base와 self align된다. 제안한 공정에서는 spin-on source를 확산원으로 사용하였고, mask 단계를 줄이기 위하여 열처리로 단단해진 spin-on source를 확산 mask로 사용하였다. 이 공정에 의하여 13단 ring oscil-lator를 포함한 시험소자를 6.5μm의 epi 충을 갖는 n/n+ silicon wafer 상에 제작하였다. 제작한 시험소자의 특성은, collector가 세 개인 I2L의 경우 npn transistor의 상향 전류이득은 최대치가 8이었으며, collector가 하나인 I2L의 속도전력적과 최소 전달 지연시간은 각각3.5 pJ과 50ns 이었다.

• 한국항공우주학회지
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• 제33권7호
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• pp.85-91
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• 2005

군용항공기는 고받음각에서 적절한 조종성 및 항공기 이탈에 대한 안정성을 확보하고 있어야 한다. 고받음각에서 항공기가 이탈에 진입할 수 있는 한계값은 항공기 형상설계에 직결되는 문제이다. 하지만 현대의 고성능 전투기는 전기식 비행제어계통을 사용하여 고받음각 제어법칙을 설계함으로써 한계 값 내에서 항공기의 안정성을 보장하고 있으며 항공기가 이탈 시, 안전하게 회복할 수 있도록 고받음각 제어법칙을 설계한다. 현재 T-50에 적용되어 있는 고받음각 제어법칙은, 세로축 방향으로는 받음각 제한기 및 MPO(Manual Pitch Override) 모드, 가로-방향축으로는 고받음각 이탈제한기, 가로축 명령제한기, 방향축 조종사 명령제한기 및 스핀방지기가 설계되어 있다. 본 논문에서는 T-50 에 적용되어 있는 고받음각 제어법칙을 소개하며, 고받음각 비행시험을 통하여 항공기 안정성에 관한 연구를 수행하였다.

• 한국가스학회:학술대회논문집
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• 한국가스학회 2005년도 추계학술발표회 논문집
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• pp.182-189
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• 2005

• International Journal of Aeronautical and Space Sciences
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• 제13권3호
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• pp.317-322
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• 2012

The low speed aerodynamic characteristics for a modified sonic arc airfoil which is designed by using the nose shape function of sonic arc, the shape function of NACA four-digit wing sections, and Maple are experimentally investigated. The small rotor blades of a modified sonic arc and NACA0012 airfoil are precisely fabricated with a commercially available light aluminum(Al 6061-T6) and are spin tested over a low speed range (3000rpm-5000rpm). In a consuming power comparison, the consuming powers of NACA0012 are higher than that of modified sonic arcs at each pitch angle. The measured rotor thrust for each pitch angle is used to estimate the rotor thrust coefficient according to momentum theory in the hover state. The value of thrust coefficients for both two airfoils at each pitch angle show almost constant values over the low Mach number range. However, the rotor thrust coefficient of NACA0012 is higher than that of the modified sonic arc at each pitch angle. In conclusion, the aerodynamic performance of NACA0012 is better than that of modified sonic arcs in the low speed regime. This test model will provide a convenient platform for improving the aerodynamic performance of small scale airfoils and for performing design optimization studies.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2011년도 제37회 추계학술대회논문집
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• pp.379-382
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• 2011

발전용 가스터빈 초기 구동용 시동시스템의 제동특성 평가를 위해 시동모터 단독 무부하 시험과 엔진 장착 부하시험을 수행하였다. 시동모터의 제동저항 용량 차이에 따른 제동 성능의 실험적 평가를 통해 가스터빈 시동과정 중 비상정지 상황에서 안정적인 제동특성을 확보하기 위한 정량적 데이터를 확보하였다. 본 연구를 통해 가스터빈의 시동 신뢰성과 안정성을 제고하기 위한 최적의 시동모터 제동저항 선정이 가능하게 되었다.

• 한국국방경영분석학회지
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• 제3권1호
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• pp.83-96
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• 1977

The combustion chamber and nozzle of an end burning, small spherical rocket is designed. A spherical external shape has a number of advantages such as fixed center-of-gravity and minimum aerodynamic precession torques during flight and a better mass distribution for gyro-stabilization as contrasted to a conventional ogive rocket shape. It is shown that the cross-sectional variation of the end burning solid propellant with length is an exponential geometry to provide a constant thrust-weight ratio of the rocket device during the propellant burning period, and that the factors which affect the attainment of the constant relationship of thrust to weight in the design are the initial propellant area, initial weight of the rocket and propellant density. The measurement of the transient thrust in the ground static test using black powder propellant supports the predicted results. A wind tunnel having a $30{\times}30{\times}75cm$ test section and Mach number 0.11 is constructed, and a simple balance-type device is designed for the measurement of the drag of a spinning sphere. The experimental results indicate that the. spinning has no effect on the magnitude of the drag up to the Reynolds number $3{\times}10^5$. Numerical computation of the flight trajectories for various launching angles is presented, and the gyro-stabilization of spinning sphere is discussed.