• 소음진동
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• 제7권3호
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• pp.427-437
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• 1997

Mean active intensity based active control for the cancellation of radiated noise out of the duct exit is studied. The active intensity control strategy is drerived based on the relation of the exterior sound field out of the duct termination and interior sound field of the duct. One of the characteristics of this control strategy is that the control performance can be maintained regardless of the sensor loction, compared with the conventional local pressure control methods at either interior downstream or exterior field positions. It is also suggested that the digital filtering for the active intensity control can be achieved by time-domain filtered-x LMP (Lest-Mean-Product) adaptive algorithm. Experiments for an open-ended duct are performed to compare the active intensity control performance with conventional pressure control one. Active control experiment of local sound pressure is conducted by widely used filtered-x LMS adaptive Algorithm and active intensity control implementaion uses the derived filter d-x LMP algorithm. It is shown that the exterior sound fileds was much better observable by sensing of the active intensity than by just sound pressure. It is also demonstrated that the global control performance of external field by acoustic intensity is superior to the conventional sound pressure control performance.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2003년도 춘계학술대회논문집
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• pp.652-657
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• 2003

This paper proposes a method to generate virtual intensity field in space. The sound field of a zone enclosing the listener position is controlled to have maximum acoustic intensity to the desired direction. In order to control acoustic intensity of a zone, space-averaged active intensity is introduced. The ratio of space-averaged active intensity and control effort is defined as a cost function and expressed as a function of source control signals. It is shown that the cost function represents radiation efficiency of multiple sources. The control signals maximizing the cost function is found through eigenvalue analysis. The proposed method is verified by numerical simulations performed in free field condition, and the results provide a relation between wavelength and the size of controllable intensity field.

• 한국산학경영학회:학술대회논문집
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• 한국산학경영학회 2005년도 추계학술발표대회 발표논문집
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• pp.1-9
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• 2005

Job search research has been criticized for failing to study the dynamics and change of the job search process. A lot of previous researches have used cross-sectional designs and treated job search as a static process. As a result, job search research has failed to examine how job seekers' behaviors change during the course of their search. This paper examined changes In job search behaviors(preparatory and active job search behavior, and job search intensity) and the effects of individual difference variables(self-esteem, self-efficacy, extroversion, agreeableness, conscientiousness, openness) on job search behaviors. Data were gathered from 404 university students who had not found employment at the time of beginning of second semester The results of t-test pairs indicated that job seeking students increased their preparatory job search behavior and active job search behavior, but didn't job search intensity. The results of multiple regression showed that self-efficacy had strong relationship with preparatory and active job search behavior, and job search intensity, but self-esteem had not any relationship with them. Among big-5 personality, extroversion had relationship with active job search behavior and job search intensity, and agreeableness only with job search intensity.

• 한국소음진동공학회논문집
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• 제20권11호
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• pp.1089-1096
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• 2010

The relation between the vibration induced from machinery and the radiated sound is complicated. Acoustic intensity method is widely used to obtain the accuracy of noise measurement and noise identification. In this study, as groundwork, the complex acoustic intensity method is performed to identify noise source and transmission path on different free space point source fields. As an industrial application, the complex acoustic intensity method is applied to HVAC to identify sound radiation characteristics in the near field. Experimental complex acoustic intensity method was applied to HVAC, it is possible to identify noise sources in complicated sound field characteristics which noise sources are related with each other, and certificate the validity of complex acoustic intensity. Especially, it can be seen that complex acoustic intensity method using both of active and reactive intensity is vital in devising a strategy for identification of noise. Also, the vector flow of acoustic intensity was investigated to identify sound intensity distributions and energy flow in the near field of HVAC.

• 한국소음진동공학회논문집
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• 제11권4호
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• pp.22-30
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• 2001

In this paper, active control of vibrational intensity at a reference point in an infinite, elastic plate was discussed. The plate is excised harmonically by a vibrating source, which has a vertical point force. The optimal condition of controller was investigated to minimize the vibrational intensity being transmitted from the vibrating source to a reference point. Hence the method of feedforward control was employed for the control strategy and then the cost function was evaluated to find the optimal control force. Three types of control force (Vertical force, Moment, and Coupling force (a set of vertical force and moment) ) and controller's positions were examined to define the optimal condition of the controller. The vibrational intensity at a reference point was found to be reduced down to a zero level, compared with the uncontrolled case. Especially maximum reduction of vibrational intensity was achieved when the controller was collinearly positioned between a vibrating source and a reference point.

• 대한물리치료과학회지
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• 제1권1호
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• pp.145-163
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• 1994

This study was done to determine differences in effect of postoperative pain control in patients receiving auricular electroacustimulation vs transcutaneous electrical nerve stimualtion following total knee replacement surgery. Thirty-one cases referred to physical therapy department after treated by total knee replacement surgery by orthopedic surgery department at the Pohang St. Mary's Hospital from January 1993 through June 1994. Of 31 total knee replacement cases, 13 cases were auricular electroacustimulation group, 11 cases were transcutaneous electrical nerve stimulation group, and 7 cases were control group. The results of the study summerized are as follows: Thirty-one total knee replacement cases(male in 12 cases, female in 19 cases), ranging in age from 34 to 61 years(mean${\pm}$SD=49.90 7.56) with diagnoses of degenerative arthritis(20 cases), rheumatoid arthritis(9 cases), and other(2 cases). In auricular electroacustimulation group, there was a significant change of pain intensity, unpleasantness, and active range of motion after treatment(p<0.01). In transcutaneous electrical nerve stimulation group, there was a significant change of pain intensity, unpleasantness, and active range of motion after treatment(p<0.01). In control group, did not show significant pre-posttreatment differences in pain intensity, unpleasantness, active range of motion(p>0.05). The mean change in pain intensity and unpleasantness, active range of motion from pretreatment baseline for the 3 groups. Auricular electroacustimulation group showed the large magnitude of increase in pain intensity and unpleasantness, active range of motion when compared to its own pretreatment cycle. Transcutaneous electrical nerve stimulation group showed small magnitude of increase in pain intensity and unpleasantness, active range of motion when compared to its own pretreatment cycle. No significant changes were observed in control group. Highly significant differences in pain intensity, unpleasantness, and active rage of motion were found using an ANOVA measures between treatment groups and control group(p<0.01). The squares correlation coefficients of pain and function measures pretreatment-posttreatment differences for each group. In treatment group, there was significant correlation between pain scale and function(p<0.001). In control group, there was no correlation between the pain scale and function (p>0.05). The continuous study is needd for many interesting issues of auricular electroacustimulation in new future.

• 정보처리학회논문지B
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• 제10B권5호
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• pp.521-526
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• 2003

본 논문에서는 영역의 경계를 추출하기 위해 영상의 밝기 정보와 곡선전개 방식을 이용한 기하 활성 모델을 제안한다. 영역의 경계를 추출하는 문제를 추출한 영역의 평균 밝기 값과 전개중인 폐곡선 영역의 밝기 값의 차론 최소화시키는 것으로 설정한다. 최적의 해를 구하는 방법으로 레벨세트 이론을 적용한 곡선전개 방법을 이용한다. 이 방식은 일반적인 활성 모델에 비해 초기 곡선 설정에 제약이 없고 동시에 여러 영역의 경계 추출이 가능하다. 제안 모델은 에지 정보가 충분치 못한 영상의 경우에도 일반적인 에지 기반 방식에 비해 추출 결과가 양호하였다. 비등방성 확산 필터를 사용하여 영상을 전처리 함으로써 보다 나은 추출이 수행되었다. CT나 MRI 영상을 이용하여 모델의 성능을 확인하였다.

• 한국체육학회지인문사회과학편
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• 제58권4호
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• pp.447-459
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• 2019

이 연구는 비활동 여성 30명을 대상으로 중강도 지속 운동(moderate-intensity continuous exercise; MICE)과 고강도 인터벌 운동(high-intensity interval exercise; HIIE) 시 감정적 반응과 신경전달물질의 차이를 규명하기 위해 실시되었다. 두 집단 모두 설계된 일회성 트레드밀 운동을 실시하였고, 동일한 운동을 1주일 간격으로 총 3회 반복 실시하였다. MICE는 환기역치(VT) 50% 수준에서 5분간 준비운동 후 90%VT 수준에서 25분간 지속운동을 실시하였고 다시 50%VT 수준에서 5분간 정리운동을 실시하였다. HIIE는 115%VT 수준에서 2분간 6회 반복하였고, 중간의 운동성 회복은 85%VT 수준에서 2분간 4회 반복하였다. 통계분석결과 MICE는 첫 번째 실험에서 운동 중 감정반응과 운동 후 즐거움에 대해 긍정적으로 나타났지만 세 번째 실험에서는 부정적으로 나타났다. 반대로 HIIE는 첫 번째 실험에서 운동 중 감정반응과 운동후 즐거움에 대해 부정적으로 나타났지만 세 번째 실험에서는 긍정적으로 나타났다. 신경전달물질의 경우 3번의 실험에서 두 집단 모두 운동전에 비해 운동 10분 후 유의하게 증가한 것으로 나타났다. 종합해볼 때 비활동 여성에게 HIIE 운동이 운동순응을 높이는 전략이 될 수 있다고 판단된다.

• 전기전자학회논문지
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• 제26권3호
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• pp.483-487
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• 2022

본 논문에서는 태양에너지 하베스팅을 위한 자가발전 아두이노 시스템을 설계하고 이의 동작을 설명한다. 이를 위해서 아두이노 시스템이 시시각각 변하는 태양에너지의 양을 센싱하고 이에 따라서 active mode와 sleep mode의 동작 시간의 비율을 스스로 조정해서 주어진 태양 빛의 세기에 대해서 최적으로 동작할 수 있는 동작 조건을 스스로 찾아가는 방법을 설명하고 이의 동작을 검증한다. 본 논문에서 개발한 active mode와 sleep mode의 동작 시간의 비율의 자가 조절을 통해서 태양 빛의 세기가 충분히 강할 경우에는 아두이노 시스템이 active mode로 지속적으로 구동되고, 태양광으로부터 전력을 충분히 공급받을 수 없는 경우 sleep mode를 사용하여 전력 소모를 최소화한다. 그 결과 active mode를 지속적으로 구동하는 것에 비해 sleep mode를 사용하는 경우 전력 소모를 최대 81.7% 줄여 에너지 소비를 최소화할 수 있다는 것을 알 수 있다. 또한 빛의 세기가 중간 수준일 때에는 active mode와 sleep mode의 비율을 빛의 세기에 맞게 적정하게 배분하여 동작하게 한다. 본 논문에서 제안한, 스스로 active mode와 sleep mode의 동작 시간 비율을 조절하는 방법은 특히 높은 전력 소비 효율 특성이 필요한 웨어러블 및 바이오-헬스용 자가발전 시스템을 에너지 효율적으로 동작시킬 때에 도움이 될 것으로 생각된다.

• 한국소음진동공학회논문집
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• 제21권9호
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• pp.787-797
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• 2011

The noise in a vehicle is an important factor for customers purchasing a car. Particularly, reduction of the noise that is generated from HVAC(heating, ventilation and air conditioning) is very important since it has considerable effects on interior noise. In general, identification of noise source is crucial to reduce noise level. The complex acoustic intensity method is widely used to obtain the accurate measurement and identification of noise source. Therefore, in the previous study, noise source of HVAC was identified through experimental approach using the complex acoustic intensity method. In this study, we are intended to confirm reduced level of noise by comparing the result between before and after modification of cam curve that is based on identified noise source of HVAC. It is found out that noise source of HVAC are motor and cam area using the complex acoustic intensity method in the previous study. We performed experiments to compare noise level between before and after modification of cam curve. Especially, it can be seen that complex acoustic intensity method using both active and reactive intensity is vital in devising a strategy for comparison to noise level. Also, the vector flow of acoustic intensity was investigated to identify sound intensity distributions and energy flow in the near field of HVAC.