• International Journal of Naval Architecture and Ocean Engineering
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• 제2권3호
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• pp.119-126
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• 2010

The response of ship roll oscillation under random ice impulsive loads modeled by Poisson arrival process is very important in studying the safety of ships navigation in cold regions. Under both external and parametric random excitations the evolution of the probability density function of roll motion is evaluated using the path integral (PI) approach. The PI method relies on the Chapman-Kolmogorov equation, which governs the response transition probability density functions at two close intervals of time. Once the response probability density function at an early close time is specified, its value at later close time can be evaluated. The PI method is first demonstrated via simple dynamical models and then applied for ship roll dynamics under random impulsive white noise excitation.

• 유통과학연구
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• 제8권1호
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• pp.35-42
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• 2010

본 연구는 종합슈퍼마켓에서 소비자 구매경향별 구매시점광고(POP)에 대한 반응과 POP를 접한 후 최종 구매단계에서의 중요 의사결정 요인과의 관계를 규명하기 위한 연구이다. 본 연구결과를 살펴보면 첫째, 종합슈퍼의 POP광고반응 중 소비자들은 엔드켑(End Cap)에 대한 반응점수가 높은 것으로 나타났으며, 둘째는 성별 충동적 구매경향에 대한 차이는 전반적으로 남성이 여성보다 높았다. 또한, 구매경향 간, 변수들 간의 상관관계를 살펴본 결과 충동적 구매와 비계획적 구매경향(r=.325), 충동적 구매경향과 즉각적 구매경향(r=.249)에서 상관관계가 있는 것으로 나타났다.(p<0.01) 본 연구 결과 소비자의 소비패턴도 점점 합리성 추구하며 계획적 쇼핑과 더불어 소비에 있어 POP 광고가 자신의 합리성 또는 계획성을 촉진시키는 요인이 되었을 때 POP 광고가 비로소 소비로 연결될 수 있다는 연구결과를 도출하였다.

• 한국음향학회지
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• 제2권1호
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• pp.48-58
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• 1983

The transient sound radiation from the impact between a steel ball and a thick plate is analyzed theoretically and compared with experiment results. The derivation process itself is difficult to analyze sound radiation characteristics theoretically for a thick plate with some resonances but may be investigated from measured data. During mechanical impacts, arbitrary driving point importance for an elastic system enables to predict by using mechanical importance method. In order to obtain approximate solution for an impact model testing, the surface Helmholtz integral formulation based on the integral expression for pressure in the field in terms of surface pressure and normal velocity is used as a basis. A simple expression is developed for an impulsive response function, which is time dependent velocity potential and pressure for an impact may then be computed by a convolution of exciting force. In estimating of elastic-acoustical correlation problems, mechanical inertance, overall transfer function and radiation resistance obtained by signal processing techniques are used. The usefulness is confirmed by applying these methods prediction of arbitray driving pint inertance, radiated sound pressure and exciting force.

• Journal of the Korean Academy of Child and Adolescent Psychiatry
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• 제26권3호
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• pp.183-189
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• 2015

Objectives : The aim of this study was to investigate Korean Wechsler Intelligence profiles and specific abilities related to attention problem of children with attention-deficit hyperactivity disorder (ADHD). Methods : The Korean Wechsler Intelligence Scale for Children-fourth edition (K-WISC-IV) and Advanced Test of Attention (ATA) were administered to 91 children and adolescents (age $8.5{\pm}2.6$ years, 73 boys) with ADHD. Pearson correlation and independent t-tests were used. Results : The means of Working Memory Index (WMI) and Processing Speed Index (PSI) showed a score of low average in K-WISC-IV. WMI scores for the K-WISC-IV showed clinically significant correlations with omission errors, commission errors, and response time variability on auditory ATA. PSI scores also showed significant correlations with response time and variability on visual ATA. In addition, significantly lower digit span backward scores were observed in hyperactive-impulsive/combined subtypes compared to inattentive subtype (t=3.60, p<.001). Conclusion : Children with ADHD showed significantly lower scores in WMI and PSI which were clinically correlated with ATA scores, and hyperactive-impulsive/combined subtypes showed poorer working memory functions in WMI. Follow-up studies are proposed.

• 한국소음진동공학회논문집
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• 제16권6호
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• pp.658-664
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• 2006

Shock vibrations are usually experienced in vehicles excited by impulsive input, such as bumps. The frequency weighting functions of the current standards in ISO 2631 and BS 6841 are to help objectively predict the amount of discomfort of stationary vibration. This experimental study was designed to develop frequency weighting shape for shock vibration having various fundamental frequencies from 0.5 to 16Hz. The specks were produced from the response of single. degree-of-freedom model to a half-sine force input. Fifteen subjects used the magnitude estimation method to judge the discomfort of vertical shock vibration generated on the rigid seat mounted on the simulator. The magnitudes of the shocks, expressed in terms of both peak-to-peak value and un-weighted vibration dose values (VDVs) , were correlated with magnitude estimates of the discomfort. The frequency weighting shapes from the correlation were developed and investigated having nonlinearity due to the magnitude of the shock.

• Ocean Systems Engineering
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• 제6권2호
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• pp.143-159
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• 2016

Cargo, such as a Tension Leg Platform (TLP), Semi-submersible platform (Semi), Spar or a circular Floating Production Storage and Offloading (FPSO), are frequently dry-transported on a Heavy Lift Vessel (HLV) from the point of construction to the point of installation. The voyage can span months and the overhanging portions of the hull can be subject to frequent wave slamming events in rough weather. Tie-downs or sea-fastening are usually provided to ensure the safety of the cargo during the voyage and to keep the extreme responses of the cargo, primarily for the installed equipment and facilities, within the design limits. The proper design of the tie-down is dependent on the accurate prediction of the wave slamming loads the cargo will experience during the voyage. This is a difficult task and model testing is a widely accepted and adopted method to obtain reliable sea-fastening loads and extreme accelerations. However, it is crucial to realize the difference in the inherent stiffness of the instrument that is used to measure the tri-axial sea fastening loads and the prototype design of the tie-downs. It is practically not possible to scale the tri-axial load measuring instrument stiffness to reflect the real tie-down stiffness during tests. A correlation method is required to systematically and consistently account for the stiffness differences and correct the measured results. Direct application of the measured load tends to be conservative and lead to over-design that can reflect on the overall cost and schedule of the project. The objective here is to employ the established correlation method to provide proper high-frequency responses to topsides and hull design teams. In addition, guidance for optimizing tie-down design to avoid damage to the installed equipment, facilities and structural members can be provided.

• 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.

• Nuclear Engineering and Technology
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• 제54권6호
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• pp.2023-2030
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• 2022

A novel pulse fitting analysis (PFA) method is presented for the acquisition of nuclear spectra. The charging process of the feedback capacitor in the resistive feedback charge-sensitive preamplifier is equivalent to the impulsive pulse, and its impulse response function (IRF) can be obtained by non-linear fitting of the falling edge of the nuclear pulse. The integral of the IRF excluding the baseline represents the energy deposition of the particles in the detector. In addition, since the non-linear fitting process in PFA method is difficult to achieve in the conventional architecture of spectroscopy system, a new multi-channel analyzer (MCA) based on Zynq SoC is proposed, which transmits all the data of nuclear pulses from the programmable logic (PL) to the processing system (PS) by high-speed AXI-Stream in order to implement PFA method with precision. The linearity of new MCA has been tested. The spectrum of ¹³⁷Cs was obtained using LaBr₃(Ce) scintillator detector, and was compared with commercial MCA by ORTEC. The results of tests indicate that the MCA based on PFA method has the same performance as the commercial MCA based on pulse height analysis (PHA) method and excellent linearity for γ-rays with different energies, which infers that PFA method is an effective and promising method for the acquisition of spectra. Furthermore, it provides a new solution for nuclear pulse processing algorithms involving regression and iterative processes.

• Journal of the Korean Academy of Child and Adolescent Psychiatry
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• 제8권2호
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• pp.242-255
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• 1997

본 연구는 비엔나 검사총집의 전산화된 검사를 포함한 다양한 주의력검사도구를 통해 주의력결핍/과잉운동장애의 특징적인 주의력결핍유형을 알아보기 위해 시행되었다. 총 9가지의 검사를 실시하여 얻어진 결과를 통해 다음과 같은 사실을 알 수 있었다. 주의력결핍/과잉운동장애아동들이 정상대조군에 비해 전반적인 경계도가 낮으며 시간이 흐름에 따른 경계도의 저하가 심하며 반응에 대한 준비도 역시 감퇴되어 있었다. 또한 감시력 검사를 통해 주의력결핍/과잉운동장애아동이 선택적 주의력의 결함을 가짐을 알 수 있었으나 지속적 주의력의 결함은 관찰되지 않았다. 이들은 정보처리용량을 초과하는 자극이 주어지는 상황에서 정상 아동들에 비해 충동적으로 반응하여 오경보오류수가 증가하였다. 전두엽기능부전에 민감한 세 가지 신경심리검사를 통하여 주의력결핍/과잉운동장애아동들의 실행능력에 결함이 있음을 알 수 있었다. 주의력결핍/과잉운동장애아동에서 나타나는 다양한 주의력의 측면에서의 결함은 이 장애가 뇌간 망상체 형성및 전두엽을 포함한 뇌의 여러 부위의 통합적인 기능이상에 의한 것이라는 가설을 지지하는 것이라고 하겠다.

• 한국자동차공학회논문집
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• 제15권2호
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• pp.50-57
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• 2007

Shocks are excited by impulsive forces and cause discomfort in vehicles. Current standards define means of evaluating shocks and predicting their discomfort, but the methods are based on research with a restricted range of shocks. This experimental study was designed to investigate the discomfort of seated subjects exposed to a wide range of vertical shocks. Shocks were produced from the responses of one degree-of-freedom models, with 16 natural frequencies (from 0.5 to 16 Hz) and four damping ratios (0.05 0.1, 0.2 and 0.4), to a hanning-windowed half-sine force inputs. Each type of shock was presented at five vibration dose values in the range $0.35\;ms^{-1.75}$ to $2.89\;ms^{-1.75}$. Fifteen subjects used magnitude estimation method to judge the discomfort of all shocks. The exponent in Stevens' power law, indicating the rate of growth in discomfort with shock magnitude, decreased with increasing fundamental frequency of the shocks. At all magnitudes, the equivalent comfort contours showed greatest sensitivity to shocks having fundamental frequencies in the range 4 to 12.5 Hz. At low magnitudes the variations in discomfort with the shock fundamental frequency were similar to the frequency weighting $W_b$ in BS 6841, but low frequency high magnitudes shocks produced greater discomfort than predicted by this weighting. At some frequencies, for the same unweighted vibration dose value, there were small but significant differences in discomfort caused by shocks having different damping ratios. The rate of increase in discomfort with increasing shock magnitude depends on the fundamental frequency of the shock. In consequence, the frequency-dependence of discomfort produced by vertical shocks depends on shock magnitude. For shocks of low and moderate discomfort, the current methods seem reasonable, but the response to higher magnitude shocks needs further investigation.