• 한국추진공학회지
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• 제23권4호
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• pp.10-20
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• 2019

충격파 개념을 이용하는 유체 추력벡터 제어는 빠른 벡터링 응답, 간단한 구조 및 낮은 무게로 인하여 큰 벡터링 성능을 달성하는데 많은 이점을 제공한다. 본 논문에서는 전산유체역학 기법을 사용하여 슬롯 인젝터를 가진 3차원 직사각형 초음속 노즐에 대하여 연구를 수행하였다. 계산 방법론을 검증하기 위하여 수치 결과를 실험 데이터로 비교하였다. 대칭 평면에서의 상부 및 하부 노즐벽을 따르는 압력분포는 시험 결과와 잘 일치하였다. $k-{\omega}$ SST 난류모델을 기반으로 한 수치해석을 통하여, 운동량 플럭스 비율의 영향을 철저히 조사하여 추력의 성능 변화를 명확하게 나타내었다.

• Structural Engineering and Mechanics
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• 제90권2호
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• pp.209-218
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• 2024

The present paper is focused on the study of the propagation of plane waves in thermoelastic media under a modified Green-Lindsay (MG-L) model having the influence of non-local and two temperature. The problem is formulated for the considered model in dimensionless form and is explained by using the reflection phenomenon. The plane wave solution of these equations indicates the existence of three waves namely Longitudinal waves (LD-Wave), Thermal waves (T-wave), and Shear waves (SV-wave) from a stress-free surface. The variation of amplitude ratios is computed analytically and depicted graphically against the angle of incidence to elaborate the impact of non-local, two temperature, and different theories of thermoelasticity. Some particular cases of interest are also deduced from the present investigation. The present study finds applications in a wide range of problems in engineering and sciences, control theory, vibration mechanics, and continuum mechanics.

• 대한정형도수물리치료학회지
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• 제26권2호
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• pp.1-10
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• 2020

Background: This study aimed to investigate the effect of hold-relax and antagonist contraction (HR-AC) technique and Kinesio taping on pain changes in delayed-onset muscle soreness (DOMS) of 20's adults. Methods: Based on voluntary participation, 14 participants with induced-DOMS were randomly divided into control (non-treatment, n=7) and experiment group (HR-AC technique and kinesio taping, n=7). Measurement were used visual analogue scale (VAS), heart rate variability (HRV), and brain wave (alpha). There were 5 sets of the HR-AC technique application on the 5th day from the day of DOMS induction (rest for 30s between sets). Kinesio taping was applied to the same area after HR-AC. Results: The VAS showed significant changes according to the period and in the interaction between the period and the group (p<.01). HRV and alpha wave (Fp1) showed significant changes according to the period (p<.001). The analgesic effect was more rapid and continuous in the experimental group than in the control group. Conclusion: This study showed that the HR-AC technique and Kinesio taping are effective interventions for the management of pain and stress caused by DOMS.

• 생물환경조절학회지
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• 제23권1호
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• pp.50-55
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• 2014

본 연구에서는 고추의 수분스트레스 반응을 최적으로 계측할 수 있는 알고리즘을 개발하기 위해 초분광 단파 적외선 영상기술을 적용하였다. 수분스트레스에 노출된 고춧잎의 단파적외선 분광영상을 획득하고 ANOVA 분석을 이용하여 수분스트레스 반응을 가장 잘 반영하는 파장영역을 선정하였다. 고춧잎의 단파적외선 초분광 영상을 이용하여 ANOVA 분석을 수행한 결과 수분스트레스 판별을 위한 최적 파장은 1449nm으로 물분자의 광흡수 영역대와 거의 일치하였다. 최적 파장에서의 고춧잎 상대반사값을 가우시안 회귀분석을 통해 정상군과 토양흡착수압이 -20kPa과 -50kPa일 때의 스트레스군을 구분할 수 있는 임계값을 계산하고 이 값을 기준으로 단파적외선 영상을 이진화하여 수분스트레스 반응을 판단할 수 있는 최종영상을 구축하였다. 결과 영상에서 정상군과 스트레스군의 토양흡착수압이 -20kPa인 잎의 경우 스트레스 반응을 보인 픽셀이 72%이었고, -50kPa인 잎에서는 스트레스 반응을 보인 픽셀이 84%로 12%차이가 났다. 정상군과 스트레스 강도가 다른 시료의 경우 영상의 결과가 명확히 구분되는 것으로 나타나 단파적외선 영상기술이 고춧잎의 수분스트레스 상태를 정량적으로 나타낼 수 있는 기술임을 확인할 수 있었다.

• 가정과삶의질연구
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• 제26권4호
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• pp.13-25
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• 2008

This study of a music therapy program for the 18 subjects residing in Jeollanam-do province was conducted two times per week during 4 months totalling 17 times in order to evaluate the reduction of the characteristics of patients suffering from stress disorder patients such as depression, and anxiety, Though the experiment for non-symmetric level the concentration and appearance of Alpha wave were determine to be stable but the findings from non-symmetric level according to the left-right brain activity were not significant for T-test, though its effective intermission of music therapy due to variation of the mean values was demonstrated, and the variation of the Alpha wave appearance rate was also significant for the statistics of the T-test for the effectiveness of the music therapy. And for the reduction of depression, emotion, and state-trait anxiety between groups divided into the control group and the experiment, pre-measurement and post-measurement comparisons through psychological tess, validated the effectiveness of music therapy for Posttraumatic stress disorder patients. First of all, this study was conducted in the situation of scarce study cases and program developments for the efficacy of music therapy for the patients suffering from Posttraumatic stress disorders without precedent studies of scientific identification through brain wave measurement. Because this study is insightful in the context of validating the efficacy of musical treatment, we expect that these kinds of studises will be continued.

• 대한의용생체공학회:의공학회지
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• 제21권3호
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• pp.261-271
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• 2000

벽면운동(wall motion)과 임피던스 페이즈앵글(impedance phase angle; 압력파와 유랑파 기아의 위상차)을 고려하여 맥동유동하에 있는 복부대동맥 분기관모델에서 2차원 전산유체해석을 수행하였다. 해석결과 분기광 근처에서응 전단응력의 크기가 매우 급격한 변화를 보임을 관찰하였고 벽면운동은 전단응력의 진폭을 감소시키는 효과를 가져왔다. 임피던스 페이즈 앵글이 음의 값을 향해 갈수록 시간 평균된 벽면 전단응력(mean wall shear stress)의 값은 감소하였으나 진폭(amplitude of wall shear stress)은 오히려 증가하였다. 페이즈앵글의 영향은 평균 벽면전단응력이 영에 근접하는 외벽(outer wall or lateral wall)의 바같쪽으로 휘어지는 부분(curvature site)에서 상대적으로 크게 나타났는데 $-90^{\circ}$ 페이즈앵글(혈류파가 혈압파를 1/4주기 앞서는 경우)일 경우에 $0^{\circ}$의 경우에 비해 평균은 $50\%$정도 감소하였고 진폭은 $15\%$정도의 상승를 나타내었다. 그러므로 고혈압 환자와 같이 큰 음의 페이즈앵글을 갖는 경우, 벽면전단응력의 평균은 낮아지고 시간에 따라 변화량(진폭)은 증가하므로 low and oscillatory wall shear stress 이론에 의하면 동맥경화에 더 민감하게 된다. 비뉴턴유체로 모델링한 경우에는 뉴턴유체의 경우에 비해 벽면전단응력의 평균값이 증가하므로서 동맥경화에 덜 민감하게 된다.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1995년도 가을 학술발표회 논문집
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• pp.164-168
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• 1995

As nation's infrastructure is getting old, nondestructive evaluation of existing structures and construction quality control are getting important. In this paper non-destructive evaluations of concrete members using impact echo and SASW methods are introduced. Both techniques are based on the stress wave propagations. Experimental tests were performed using beam type concrete member where voids and cracks are included. Within reasonable accuracy, void locations were detected using impact echo method and the dynamic modulus of concrete were measured using SASW method. Both NDT methods showed a feasibility for the implementation into quality evaluaton of concrete members in practice

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1998년도 가을 학술발표대회 논문집(III)
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• pp.743-748
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• 1998

As nation's infrastructure is getting old, nondestructive evaluation of existing structures and construction quality control are getting important. In this thesis, flaw detection techniques of concrete members with asphalt using impact echo test were introduced. This techniques are based on stress wave propagation. In this field impact echo test, As load is gradually increased, frequency is increased. From this change of frequency through impact echo test, we can detect that the crack of bridge ascends and what the depth of crack is.

• 대한통합의학회지
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• 제11권3호
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• pp.11-23
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• 2023

Purpose : The stress of job-seeking college students is gradually worsening due to the continuing recession in the job market. Therefore, this study aims to verify whether intervention with an 'aromatherapy education program,' which combines theory and practice, has greater effect on stress, self-efficacy, and autonomic nervous system function than simple inhalation of essential oils in female college students preparing for employment. Methods : A single-blind, randomized controlled trial was conducted once a week for a total of 4 weeks with 29 female college students preparing for employment. Interventions included essential oil inhalation combined with an aromatherapy education program (experimental group(EG), n=14) and essential oil inhalation alone (control group(CG), n=15); measurements were taken before, immediately after, and 2 weeks after completion of the intervention. Evaluations were conducted using the job-seeking stress scale, stress VAS, self-efficacy scale, and a pulse-wave measuring instrument. Results : There were significant differences between the CG and EG groups with repeated measurements of job-seeking stress (p=.003), cognitive stress (p<.001), and self-efficacy (p<.001). There was a significant interaction between group and time. There were also significant differences between the CG and EG in terms of autonomic nervous system changes stress index(p=.047), total power(p=.029), high frequency(p=.036), and low frequency/high frequency ratio(p=.049). However, there was no significant difference in low frequency between the groups. Conclusion : The aromatherapy education program was more effective in improving job-seeking stress, cognitive stress, self-efficacy, and autonomic nervous system function than simple essential oil inhalation. For the aromatherapy education program to be useful as a complementary intervention for stress management in job seekers, it will be necessary to gather additional evidence of its efficacy by conducting follow-up studies with diverse participants and expanding the numbers, and durations, of the interventions.

• 한국식품영양학회지
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• 제13권6호
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• pp.602-610
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• 2000

Taekukkwon was practiced far health previously. The experimental group consisted of undergraduate and graduate students practising in the above disciplines at Myong Ji University. The group consisted of three female and three male students and the aim of this research was to measure the brain wave change for opened and closed eyes. The result of this research are as follows. Firstly, when students were subjected to basic open eye brain wave tests, beta-waves displayed for all regions of the brain. In the frontal region fast beta-waves were displayed and in the central region alpha-waves were displayed. Secondly, in the closed eye brain wave tests, the control group displayed beta-waves in some regions and alpha waves in external and internal regions. For all students\` brain-wave patterns, the amplitude of the alpha-wave was low and the frequency was high. In some students theta-waves were displayed. Taekukkwon practice relaxes the mind and body and helps relieve social stress which shows that taichichuan practices is beneficial. Finally, characteristics of the subjects were mostly type A so the personalities of the subjects were fast and aggressive. This research shows a definite link between personality and personal relationships with beta-waves emissions. So, further research is required in the future to investigate this relationship. The subjects consumed too large amount of foods so it was necessary to change their dietary habits taking into consideration on total calories, fats, and protein. It was also necessary to carrying out nutrition education to the students in emphasizing appropriate attitudes in general health and dietary behavior.