• 대한의용생체공학회:학술대회논문집
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• 대한의용생체공학회 1996년도 추계학술대회
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• pp.277-280
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• 1996

We have developed a ground-isolation circuit in order to reduce the noise of the internal controller system for the total artificial heart(TAH) and ventricular assist device(VAD). Using the ground-isolation technique, we could transmit the analog target signal to other pheriperal device including IBM PC via RS232C and polygraph, with no noise. Experimental results of VAD showed that there was less impulsive noise in current signal which caused in our previous conventional system. Therefore it could be proved that implementation of isolation technique is very effective to improve the signal to noise ratios of analog signal transmission for TAH or VAD.

• Journal of Astronomy and Space Sciences
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• 제33권4호
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• pp.323-333
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• 2016

In this study, the uncertainty requirements for orbit, attitude, and burn performance were estimated and analyzed for the execution of the $1^{st}$ lunar orbit insertion (LOI) maneuver of the Korea Pathfinder Lunar Orbiter (KPLO) mission. During the early design phase of the system, associate analysis is an essential design factor as the $1^{st}$ LOI maneuver is the largest burn that utilizes the onboard propulsion system; the success of the lunar capture is directly affected by the performance achieved. For the analysis, the spacecraft is assumed to have already approached the periselene with a hyperbolic arrival trajectory around the moon. In addition, diverse arrival conditions and mission constraints were considered, such as varying periselene approach velocity, altitude, and orbital period of the capture orbit after execution of the $1^{st}$ LOI maneuver. The current analysis assumed an impulsive LOI maneuver, and two-body equations of motion were adapted to simplify the problem for a preliminary analysis. Monte Carlo simulations were performed for the statistical analysis to analyze diverse uncertainties that might arise at the moment when the maneuver is executed. As a result, three major requirements were analyzed and estimated for the early design phase. First, the minimum requirements were estimated for the burn performance to be captured around the moon. Second, the requirements for orbit, attitude, and maneuver burn performances were simultaneously estimated and analyzed to maintain the $1^{st}$ elliptical orbit achieved around the moon within the specified orbital period. Finally, the dispersion requirements on the B-plane aiming at target points to meet the target insertion goal were analyzed and can be utilized as reference target guidelines for a mid-course correction (MCC) maneuver during the transfer. More detailed system requirements for the KPLO mission, particularly for the spacecraft bus itself and for the flight dynamics subsystem at the ground control center, are expected to be prepared and established based on the current results, including a contingency trajectory design plan.

• 한국해양학회지:바다
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• 제9권3호
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• pp.111-118
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• 2004

한국 동해시에서 약 10 km떨어진 수심 130 m해역에 실시간 동해 해양관측 부이를 계류하여 기상(기온, 기압, 풍속, 순간최대풍속, 풍향, 상대습도) 및 해양(파랑, 해수물성, 전층해류) 자료를 실시간으로 수집하였다. 2003년 9월 13일 03:00에 태풍 매미의 눈이 한국 울진시 부근을 통과할 때, 순간최대풍속은 25 m/s(10분 평균풍속은 최대 20 m/s) 그리고 최저기압은 980 hPa로 기록되었다. 파고는 이로부터 한 시간 뒤인 04:00에 최대가 되었으며 유의파고는 4 m 그리고 최대파고는 9 m에 이르렀다. 표층부근에서 측정된 유속은 태풍의 눈이 통과한 뒤 점차 증가하여 약10시간 뒤인 13:00에는 약 100 cm/s에 달하였고 그 방향은 남남동이었다. 강한 남남동향류를 동반한 표층혼합층은 고온저염의 특성을 유지하였으며, 그 두께는 같은 10시간동안 20 m에서 40 m로 서서히 증가하였다. 일정경사면의 해저지형을 가지는 해양에서 해안선방향의 순간 바람에 대한 이층유체의 반응을 알아보기 위해 Csanady(1984)가 제안한 간단한 해석모형을 적용하였다. 그 결과 실시간 해양관측부이의 계류 위치(x=8.15 km)에서 태풍의 눈 통과 후 10시간동안 전개된 해안선 방향과 이에 수직한 방향의 유속구조와 상하층의 경계에 대한 적절한 추정치를 얻을 수 있었고, 태풍 매미 통과 후 동해시 연안해양의 특징적인 반응을 부분적으로 설명할 수 있었다.

• 수산해양기술연구
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• 제21권1호
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• pp.12-18
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• 1985

고압변압기의 1차측을 제어하고 2차측에 유도된 전압을 이용한 수중방전음원의 전기음향학적 제특성을 분석.검사한 결과는 다음과 같다. 1. 방전시 2차측 전류는 초기에는 Ohm 법칙을 따르다가 전류가 최고 6.3A 흘러 절연 파괴되었으며, 그 순간 방전음이 생성되었다. 2. 전류인가점과 방전음 생성문의 시간차는 약 3ms였으며, 전압이 최고일 때 절연파괴가 일어나 방전음이 생성되었다. 3. 전극의 끝이 뾰족할수록 2차측 전압이 높을수록 음압수준은 높았다. 4. 뾰족한 형태의 전극은 전극간격이 100cm일 때도 방전이 일어났으며 전극간격이 1cm이상부터 비교적 안정된 방전음이 생성되었다. 5. 방전음의 펄스폭은 약 0.15ms인 Shock Wave였으며, 10HKz 이하의 합성저주파 성분이었다.

• 정신신체의학
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• 제7권1호
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• pp.26-41
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• 1999

본 연구의 목적은 4가지 스트레스반응 즉 감정적 신체적, 인지적, 행동적 반응들을 측정할 수 있는 스트레스반응지각 척도를 개발하고자 하는데 있다. 일차로 성인 193명(정신과외래 내원환자 84명, 정상인 109명)을 대상으로 스트레스반응지각 척도 예비설문을 시행하여 109문항을 추출하였다. 2차로 이 문항들이 포함된 설문을 환자군 242명(불안장애 71명, 우울장애 73명, 신체형장애 47명, 정신신체장애 51명)과 정상대조군 215명을 대상으로 실시하였다. 이 자료들을 감정, 신체, 인지, 행동 4가지 영역에서 요인 분석한 결과 8개의 하위요인 즉 부정적 감정, 일반적 신체증상, 특정 신체증상, 인지기능저하 및 일반적 부정적 사고, 자기비하적 사고, 충동공격적 사고, 수동반응적 및 부주의 행동, 충동공격적 행동이 추출되었다. 상기 척도의 신뢰도는 130명(환자군 68명, 정상대조군 62명)에게 2주 간격으로 검사 재검사를 시행, 분석한 결과 8개 하위척도 점수와 척도 전체 점수 간의 상관계수가 .83~.93으로 모두 유의한 상관성을 보였다. 한편 내적 일치도는 8개 하위척도의 Cronbach' s alpha가 .79~.96. 척도 전체의 Cronbach's alpha가 .98이었다. 공존타당도는 global assessment of recent stress(GARS) scale, perceived stress questionnaire(PSQ). symptom checklist-9D-R(SCL-9D-R)의 전체지표 각각의 총점과 본 척도의 8개 하위척도의 점수 및 척도 전체점수 간의 상관성을 각각 비교한 결과 모두 유의하게 높은 것으로 나타났다. 변별타당도는 환자군과 정상군 간에 척도의 총점과 8개 하위척도 점수를 비교한 결과 충동공격적 행동을 제외한 7개 하위척도 점수와 총점에서 각각 유의한 차이를 보였다. 이상의 결과들은 스트레스반응지각 척도가 신뢰도 및 타당도가 모두 유의한 수준으로 정신신체의학을 비롯한 스트레스에 관련된 분야의 연구에 효과적으로 이용될 수 있는 도구임을 시사해 준다.

• 유통과학연구
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• 제13권1호
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• pp.71-81
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• 2015

Purpose - This study aims to examine the effect of audience attitude toward product placement, or PPL, on product attitude and purchase intention. PPL has increasingly been prevailing in TV dramas since the revision of the Broadcasting Act in January 2010, and it is quite widespread in today's society. Therefore, this study intends to investigate how the audience would take a particular attitude toward PPL in TV dramas and how their attitude would affect their product attitude and purchase intention. Research design, data, and methodology - The sample for the current study was drawn from college students in Seoul in December 2013, as the main targets of the products and brands that were advertised by PPL are young people. The questionnaire for this study comprised nine parts, such as the knowledge of PPL, experience of PPL, TV drama watching time, impulsive buying propensity, celebrity imitating buying propensity, attitude toward PPL, attitude toward product, purchase intention, and demographic characteristics. The questionnaire items were measured by 5-point Likert scales. Whether the demographic characteristics and propensity to consume would affect PPL attitude was analyzed and how the PPL attitude would affect purchase intention through product attitude was analyzed as well. To analyze the relationship between variables, structural equation modeling analysis was performed with Amos 18.0. Results - The major findings of the study were as follows. First, whether the demographic characteristics and propensity to consume would affect PPL attitude was analyzed, and it is found that out of the demographic characteristics, only gender and knowledge of PPL exerted an influence on PPL attitude. In addition, celebrity-imitating buying propensity had an impact on PPL attitude. Second, whether PPL attitude would affect purchase intention through product attitude was analyzed by structural equation modeling. Consequently, it is found that PPL attitude impacted purchase intention through product attitude. Conclusions - The findings of the study had the following implications. First, in theoretical aspects, previous studies have proven only that attitude toward PPL influenced attitude toward product and purchase intention separately; however, the current study has investigated the mediated role of attitudes toward PPL. Second, regarding the practical aspects, as PPL attitude exercised an effect on purchase intention as well as product attitude, PPL should be utilized in a manner to stimulate the audience to take a positive attitude to it. Finally, gender, PPL knowledge, and celebrity-imitating buying orientation were identified as influential factors for PPL attitude. Specifically, female consumers showed a lower attitude toward PPL than males, and the consumers who have no knowledge showed a lower attitude toward PPL. The consumers who have celebrity imitating buying propensity expressed a higher attitude toward PPL. These factors should consequently be taken into account when PPL is planned and conducted. The current study has limitations such as the sample object, non- experimental method, and media biases. Therefore, future research should be conducted to address these limitations.

• 한국전자파학회논문지
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• 제16권12호
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• pp.1246-1254
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• 2005

등방성 상반 매질과 수직 단축성 하반 매질의 경계면에서 $VV{\cdot}HV{\cdot}VH$ 문제에 대해, 임펄스 점전류원에 의해 발생하는 전자장을 이론적으로 고찰한다. 이들 문제에서의 전기장은 Fourier-Laplace 영역의 이상파 성분과만 관련이 있다. 각각의 문제에 대해서 Cagniard-de Hoop 해석법을 응용하여 시간 영역의 전자장 해를 얻는다. VV 문제의 전자장은 적분이 포함되지 않은 명시적인 형태로 구할 수 있다. $HV{\cdot}VH$ 문제의 해에서는 적분을 없앨 수 없지만, 적분해에 내재 된 주요 특이 성분들은 해석적으로 추출된다. 주파수 영역의 계면 원방 전자장은 시간영역의 특이 성분에 의해 결정된다.

• 대한조선학회논문집
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• 제53권4호
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• pp.315-328
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• 2016

Techniques for determinating hydrodynamic derivatives of underwater tow-fish using CFD(Computational Fluid Dynamics) are described in this paper. Main components of hydrodynamic derivatives are added mass, linear damping and non-linear damping coefficients. In this study, linear and non-linear damping coefficients for translational velocities are settled by CFD analysis. In order to analyze the underwater tow-fish, UlsanFOAM based on open-source CFD code, namely OpenFOAM, is employed. By simulating pitch and yaw angle variation of underwater tow-fish, 6DOF(Degree-of-Freedom) forces and moments are estimated at each attitudes. In order to determinate the hydrodynamic derivatives, curves(forces and moments vs attitude) for CFD results are fitted by least square methods. To demonstrate the applicability of the current approach, two different problems(impulsive side towing and straight towing) are simulated and all results are validated.

• Biomolecules & Therapeutics
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• 제16권4호
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• pp.343-350
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• 2008

Oroxylin A is a flavonoid isolated from Scutellaria baicalensis, which is one of the most important medicinal herbs in traditional Korean medicine. In this study, we investigated the psychopharmacological activities of oroxylin A using the open field, rota-rod, balanced wire and plus-maze tests in Spontaneously Hypertensive Rats (SHR) and Wistar Kyoto Rats (WKY). Oroxylin A reduced hyperactivity in SHR (ADHD animal model) although it tended to increase locomotor activity in WKY. Methylphenidate did not reduce hyperactivity. Oroxylin A alleviated impulsive behaviors such as rearing, the percentage of moving time to the central area and the tendency to move into an unstable condition (open area in elevated plus-maze). Methylphenidate also reduced the percentage of staying time in the central area and the tendency to move into an unstable condition. Both oroxylin A and methylphenidate enhanced motor attention in SHR and WKY. Oroxylin A antagonized the muscimol ($GABA_A$ receptor agonist)-induced $Cl^-$current and its action was similar to that of bicuculline ($GABA_A$ receptor antagonist). The effects of oroxylin A may be caused by the antagonism at the $GABA_A$ receptor. Thus, oroxylin A may be a candidate of drug for treatment of ADHD.

• Structural Engineering and Mechanics
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• 제77권4호
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• pp.441-461
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• 2021

Reinforced concrete (RC) columns are crucial in building structures and they are of higher vulnerability to terrorist threat than any other structural elements. Thus it is of great interest and necessity to achieve a comprehensive understanding of the possible responses of RC columns when exposed to high intensive blast loads. The primary objective of this study is to derive analytical formulas to assess vulnerability of RC columns using an advanced numerical modelling approach. This investigation is necessary as the effect of blast loads would be minimal to the RC structure if the explosive charge is located at the safe standoff distance from the main columns in the building and therefore minimizes the chance of disastrous collapse of the RC columns. In the current research, finite element model is developed for RC columns using LS-DYNA program that includes a comprehensive discussion of the material models, element formulation, boundary condition and loading methods. Numerical model is validated to aid in the study of RC column testing against the explosion field test results. Residual capacity of RC column is selected as damage criteria. Intensive investigations using Arbitrary Lagrangian Eulerian (ALE) methodology are then implemented to evaluate the influence of scaled distance, column dimension, concrete and steel reinforcement properties and axial load index on the vulnerability of RC columns. The generated empirical formulae can be used by the designers to predict a damage degree of new column design when consider explosive loads. With an extensive knowledge on the vulnerability assessment of RC structures under blast explosion, advancement to the convention design of structural elements can be achieved to improve the column survivability, while reducing the lethality of explosive attack and in turn providing a safer environment for the public.