• 대한전자공학회논문지
• /
• 제27권1호
• /
• pp.51-58
• /
• 1990

NPN Si bipolar transistors with two different emitter widths are designed and fabricated. The effects of the emitter width on the small signal parameters of BJTs are measured and discussed. A new ac method for determining the current gain, the cut off frequency and the internal capacitances from the input impedance circle characteristics as a function of the varied external series resistances is presented. This method allows an accurate characterization of bipolar transistors with high current gain. The variation of the I-V curves of the emitter junction with the reverse collector junction voltages is discussed from the changes in the intsrinsic base resistances.

• Journal of the Korean Data and Information Science Society
• /
• 제16권2호
• /
• pp.477-505
• /
• 2005

This paper gives a computer code that gives p-value's for Kendall's Tau table. The code centers around finding the cumulative frequency of a given Sigma value. Current tables usually give critical values for given cut-off percentages. For small sample sizes the critical values may be inexact, and for large samples the values are not be published. SPSS has a built in function for finding the Kendall rank correlation, but the output does not include the Sigma value. Before the code is given, this paper will concentrate around how to find the Sigma value, and the related tau statistic. The computer code is written in MATLAB, but the ideas can be easily transferred to different languages.

• 전력전자학회:학술대회논문집
• /
• 전력전자학회 2005년도 전력전자학술대회 논문집
• /
• pp.584-586
• /
• 2005

The stroke of piston in the linear compressor driven by LPMSM can be obtained from integrating the input voltage and current of LPMSM, and may be diverged due to dc components In the voltage and current. The strategy to prevent the divergence of stroke using both the high-pass filter and dc offset compensation was suggested. The equations for the magnitude and phase of the stroke and also dc offset including the stroke are derived as a function of the cut-off frequency of HPF. The performance of stroke calculation scheme has been verified by experimentally on a linear compressor drive system, where the control was implemented by a 16-bit DSP.

• 전기학회논문지
• /
• 제66권12호
• /
• pp.1732-1739
• /
• 2017

This paper presents a sensorless vector control algorithm of closed loop Gopinath flux observer to enhance the robustness at low speed by switching P/PI mode. Closed loop Gopinath flux observer has the problem in sensorless vector control of induction motor at low speed. This paper solves the problem using the characteristic function of closed loop Gopinath flux observer. P mode shows better performance than PI mode under the cut-off frequency of observer. But P mode always has a flux error due to DC offset, so this paper combines P mode and PI mode. This algorithm shows good performance over wide speed range. The performance has been confirmed through computer simulations using MATLAB SIMULINK and experiments.

• 한국소음진동공학회:학술대회논문집
• /
• 한국소음진동공학회 2000년도 추계학술대회논문집
• /
• pp.737-741
• /
• 2000

Portable communication devices such as laptop computers suffer impact-induced failure in their usage. Drop/impact performance of these products is one of important concerns of product design. Because of the small size of this kind of electronics products, it is very expensive, time-consuming and difficult to conduct drop tests to directly detect the failure mechanism and identify their drop behaviors. Finite element analysis provides a vital, powerful vehicle to solve the problems. The models are created with HYPERMESH, and the analysis is carried out with LS-DYNA3D. The analysis is focused on HDD impact behavior in acceleration peak values.

• 중환자간호학회지
• /
• 제13권3호
• /
• pp.75-85
• /
• 2020

Purpose : This study aimed to identify the prevalence and risk factors of cognitive impairment in survivors discharged from the intensive care unit (ICU). Methods : This secondary analysis study utilized data from a multicenter prospective cohort of post-ICU patients. We analyzed the data of 175 patients enrolled in the primary cohort who completed the cognitive function evaluation three months after ICU discharge. Cognitive function was assessed using the Montreal Cognitive Assessment (MoCA) scale. The cut-off points for cognitive impairment were < 23 for face-to-face evaluation and < 18 for telephone evaluation. Results : The prevalence of cognitive impairment three months after ICU discharge was 32.6%. Significant risk factors for cognitive impairment were age ≥ 60 years (OR=10.52, 95% CI=3.65~30.33, p<.001), education < high school graduation (OR=2.53, 95% CI=1.07~6.01, p=.035), unplanned ICU admission (OR=4.01, 95% CI=1.45-11.14, p=.008), and delirium in the ICU (OR=4.33, 95% CI=1.08-17.23, p=.038). Conclusion : ICU nurses should use preemptive strategies to reduce post-ICU cognitive impairment of patients with risk factors. It is necessary to frequently assess and detect early delirium in critically ill patients, while attempting various non-pharmacological interventions.

• 한국통신학회논문지
• /
• 제11권5호
• /
• pp.315-322
• /
• 1986

本 論文은 　圓函數를 利用한 IIR digital 필터 設計에 關하여 硏究한 것이다. Digital 　圓函數는 analog 　圓函數로부터 Bilinear z 變換에 依하여 求하였다. Bilinear z 變換된 函數로 digital필터를 設計하면 aliasing 現象은 避할 수 있으나 周波數歪曲이 發生한다. Analog函數를 digital函數로 變換하면 이러한 影響으로 遮斷周波數 領域이 不一致하므로 이것을 避하기 爲하여 prewarping法을 利用하였다. 마지막으로, 컴퓨터 simulation에 依하여 analog 크기 特性과 digital 크기 特性을 比較한 結果, prewarping을 한 digital 크기特性이 analog 크기 特性에 比하여 改善되었음을 確認할 수 있었다.

• 대한전기학회논문지:시스템및제어부문D
• /
• 제49권8호
• /
• pp.459-466
• /
• 2000

In this paper, we propose an attitude controller for an unstructured object using CMG(Control Moment of Gyro) subsystem, which has a stabilizer function. The CMG subsystem consists of one motor for spinning the wheel and the other motor for turning the outer gimbal. While the wheel of CMG subsystem is spinning at high speed, applying force to the spin axis of the wheel leads the torque about the vertical axis. We utilize the torque to control the attitude of object in this study. For the stabilizer function, in additiion, holding the load at the current position, the power applied to the gimbal motor of CMG will be cut, which result in the braking force to stop the load by gyro effect. However, due to the gear reduction connected to outer gimbal, slow load motion cannot generate the braking force. Thus, in this study, we are willing to make a holding force by applying control power to the gimbal motor from the signal of piezoelectric gyroscopic sensor that detected the angular velocity of the load. These two features are demonstrated in experiment, carrying a beam with crane. As a result, load was started to rotate by controlling gimbal positiion and was stopped by turning off the gimbal power. Moreover, slow movement of the load was also rejected by additional control with gyroscopic sensor.

• 대한건축학회논문집:계획계
• /
• 제35권9호
• /
• pp.3-9
• /
• 2019

Modern cities have been clustered with spaces defined by specific functions, while standardized with well-defined areas. The monopoly of the function reduces the publicity of the space and hinders people's daily communication. Street also be overwhelmed by the function of being a "passage", traditional streets were losing their liminality. In fact, the street was a place of meeting, a place of events, and a place of freedom to broaden the choices of behavior. The freedom to stop or walk on one'sits own, be attracted by unforeseen events that are available on traditional streets, has become rare on the streets of big cities. Life has become dull and monotonous, too, through the modelling of the street system. Cities have become grim as communities are cut off and fragmented. In today's big cities, public attention to the liminality of the traditional streets need to be aroused so that people could gather freely and have a festival time.

• 한국콘텐츠학회논문지
• /
• 제14권3호
• /
• pp.269-276
• /
• 2014

본 연구에서는 라쉬분석을 통하여 한글판 학교기능평가(School Function Assessment)도구의 구성타당도, 척도 적합성을 검증함으로써 이 평가도구의 국내 사용을 위한 기초자료를 제시하고자 한다. 서울 및 경기, 충청 지역의 만 7세~12세(초등학교 1학년~6학년)인 98명 장애아동을 대상으로 아동의 보호자 및 담임 특수교사 또는 작업치료사와 직접 면담 또는 전화를 통하여 자료를 수집하였다. 자료분석은 라쉬분석을 통하여 단일차원모형(unidimensionality)에 대한 적합통계치(fit statistics)를 제시하였다. 또한, 라쉬분석의 평정척도모형(rating scale model)을 이용하여 평정척도의 적합성 분석을 실시하였다. 라쉬분석 결과 각 25개 하위척도 내 총 328개 항목 중 단일모형 적합통계치가 부적합한 항목은 Part II 과제지원 영역에서 총 4개였고, Part III 신체적 과제 영역에서 부적합 항목은 18개, 인지/행동적 과제 영역에서 부적합 항목은 14개 항목으로 나타났다. 한글판 학교기능평가 도구의 모든 평가 하위영역의 5점 평정척도는 적합한 것으로 나타났다 본 연구를 통하여 한글판 학교기능평가 도구의 구성타당도와 평정척도 적합성을 확인하였다. 그 결과 5점 평정척도는 적합한 것으로 나타났으나, 일부 부적합 항목이 발견되어 앞으로 국내 타당도 확립과 준거제시를 위한 연구가 추후 이루어져야 할 것으로 판단된다.