• 지구물리와물리탐사
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• 제25권3호
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• pp.99-108
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• 2022

유도분극(induced polarization; IP) 탐사 중 광대역 혹은 빛띠(spectral) IP (SIP) 탐사법에서는 교류 전류를 송신원으로 하였을 때 나타나는 매질의 진동수에 따른 복소전기비저항의 크기와 위상을 측정하며, 진동수에 따라 값이 변화하는 복소전기비저항의 분산 혹은 이완 반응을 분석하게 된다. 이때 분산곡선은 등가회로 모델과 같은 이완 모델을 통해 설명할 수 있는데, 다중목적함수 최적화 기법을 적용하여 분산곡선에서 SIP 이완모델의 변수들을 예측해보았다. SIP 이완현상을 설명하기 위해 가장 많이 이용되는 Cole-Cole 모델 계열의 변수를 구하기 위해 크기 오차와 위상 오차를 최소화하는 두 가지 목적함수로 설정하고 다중목적함수를 최적화하기 위해 유전 알고리듬을 이용하였다. 다중목적함수 최적화 기법을 이용한 Cole-Cole 모델 변수 구하기는 수치 모델에 대해서는 잘 구해졌으나 기존에 보고된 SIP 실내실험 자료에 피팅할 경우, 주로 위상 크기가 작을 때(약 10 mrad 이하) 피팅이 맞지 않는 경우가 많았다. 이는 다중목적함수로 사용하는 크기와 위상의 자료 오차 사이에 스케일이 맞지 않아 발생하는 한계로 추정되며, 향후 복소전기비저항의 분산 곡선에서 SIP 변수를 예측하기 위해 이러한 한계를 극복할 수 있는 기계 학습 등 다양한 기법들에 대한 연구가 필요할 것으로 판단된다.

• Archives of Pharmacal Research
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• 제27권6호
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• pp.646-652
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• 2004

The objective of this study was to determine the acute effect of trimetazidine (TMZ) on the pre-fatigue, fatigue and post-fatigue contractile characteristics and tension-frequency relationships of isolated rat diaphragm muscle. Muscle strips were taken from the ventral-costal aspects of the diaphragm muscle of rats killed by decapitation. The muscle strips were suspended in organ baths containing Krebs solution, with a gas mixture of 95% $O_2$ and 5% $CO_2$ at $37^{\circ}C$ and pH 7.35-7.45. After determining the thermoregulation and optimum muscle length the muscles were subjected to direct supramaximal stimulation with 0.05 Hz frequency square pulses for periods of 0.5 msec to obtain control values. After adding $5{\times}10^{-6}{\;}and{\;}5{\times}10^{-5}$ M trimetazidine solution to the respective bath media, the contractile parameters of the muscles were recorded. The contractile parameters were also recorded for both the trimetazidine and tri-metazidine-free media after application of the high frequency fatigue protocols. Later, the tension-frequency relationship was determined by applying stimulating pulses of 10, 20, 50 and 100 Hz to the muscle strips. Whilst the twitch tension obtained from the $5{\times}10^{-6}{\;}and{\;}5{\times}10^{-5}$ M trimetazidine media showed numerical increases compared to that of the controls, these were not statistically significant (p>0.05). The contraction time exhibited a dose dependent increase (p<0.001), whilst the contraction and relaxation rates did not differ significantly. The isometric contraction forces obtained with the different stimulating frequencies showed a significant increase in the tetanic contraction only at 100 Hz (p<0.05). A comparison of the pre- and post-fatigue twitch tensions in the trimetazidine media showed the post- fatigue twitch tensions to be significantly higher than those of the pre-fatigue contraction forces (p<0.05). In the $5{\times}10^{-6}{\;}and{\;}5{\times}10^{-5}$ M trimetazidine media the increases in the post-fatigue contraction force were 22 and 30%, respectively. These results demonstrated that in isolated rat diaphragm muscle, TMZ significantly limited the mechanical performance decrease during fatigue. It is our opinion that trimetazidine contributed to the observed fatigue tolerance by eliminating the factors of fatigue, due to preservation of intracellular calcium homeostasis, provision of the ATP energy levels needed by ATPase dependent pumps and especially by keeping the intracellular pH within cer-tain limits.

• 한국환경생태학회지
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• 제29권6호
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• pp.858-864
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• 2015

문둥이박쥐(Eptesicus serotinus)의 생후 발성발달 특징을 파악하기 위하여 임신한 암컷 3개체로부터 총 4개체의 새끼 박쥐를 확보하여 발성변화를 분석하였다. 녹음 및 분석은 생후 1일부터 40일까지 수행하였으며, 펄스 지속시간(PD), 펄스 간격(PI), 최고 주파수(PF), 시작 주파수($F_{MAX}$), 종료 주파수($F_{MIN}$), 대역폭(BW)에 대하여 측정하였다. 새끼 박쥐는 생후 초기에 가장 다양한 패턴의 음성을 발산하였으며, 연령이 증가함에 따라서 점차 어미와 유사해졌다. PD와 PI는 연령이 증가할수록 감소하였으며, 반면 PF, $F_{MAX}$, $F_{MIN}$, BW는 증가하였다. PF, $F_{MAX}$, $F_{MIN}$, BW는 생후 10일에서 20일 사이에 가장 큰 변화가 확인되었으며, PD는 생후 30일에서 40일 사이에 가장 큰 변화가 확인되었다. 따라서 진동수의 발성과 관련이 있는 발성근육의 수축 능력은 생후 20일경 가장 발달하게 되며, 발성시간과 관련된 발성근육의 이완 능력은 생후 30일에서 40일 사이에 가장 발달하는 것으로 판단된다. 본 연구에 이용된 새끼 개체들은 생후 40일차에도 비행이 확인되지 않았으나 발성음은 어미와 유사하게 나타났다. 따라서 이러한 결과는 새끼 박쥐의 발성 발달은 비행행동 또는 비행과 관련된 근육의 발달을 필수적으로 동반하는 것은 아니라는 것을 보여주는 결과라 판단된다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1999년도 하계학술대회 논문집 D
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• pp.1563-1565
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• 1999

Linear and nonliear complex permittivities have been measured for amorphous copolymers of vinylidene cyanide (VDCN) with vinyl acetate (VAc), vinyl propionate (VPr), vinyl benzoate (VBz), styrene (St) and methyl methacrylate (MMA). It is found that the third order permittivity ${\varepsilon}_3$ depends upon frequency according to a function ${\Delta}_{{\varepsilon}_3}/(1+i{\omega}{\tau}_^3)$ while the linear permittivity obeys a Debye function ${\Delta}_{{\varepsilon}_1}/(1+i{\omega}{\tau}_1)$. Experimental results are well fitted by the above predicted functions except at low frequencies where dc conduction dominates. The ${\tau}_1$ and ${\tau}_3$ are nearly equal, and depend upon temperature according to a WLF form. The relaxation strength ${\Delta}_{{\varepsilon}_1}$ depends upon comonomers ranging from $130_{{\varepsilon}_0}$(VAc) to $20{{\varepsilon}_0}$(MMA). The ${\Delta}_{{\varepsilon}_3}$ is negative and depends more strongly upon comonomers. Combined knowledge about linear and nonlinear permittivities predicts very large correlation factors which indicates strongly cooperative dipolar motions in those amorphous copolymers.

• Applied Microscopy
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• 제47권3호
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• pp.126-130
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• 2017

The dielectric relaxation characteristics of composites with different concentrations of carbon nanotubes loaded in an epoxy polymer matrix has been studied as a function of frequency over a wide range (1 Hz~10 MHz) at room temperature. Two characterization techniques were used in this work to measure and calculate the dimensionality parameters: small angle neutron scattering and impedance spectroscopy. The results obtained from both methods are in good agreement, indicating the reliability of the estimated fractal dimension, despite of the difference in the length scales accessed by the two techniques.

• 지역사회간호학회지
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• 제10권1호
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• pp.252-261
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• 1999

The purpose of this study was to investigate the daily stress and stress coping behavior of elementary school children. The subjects for this study were 372 children fourth, fifth and sixth graders from an elementary school in Pusan. We adopted Won - Joo Chung's research instrument (1997) for measuring stress and coping behavior in this study. Statistical techniques such as frequency, percentage, mean, standard deviation, order, and Pearson correlation were used to examine the research questions of this study. The results of this study were as follows: 1. The most common instance of stress to be experienced by all children was the stress from school life, followed by social pressures, individual pressures and family environment. 2. A positive revaluation was the most commonly used stress-coping behavior, followed by behavioral mood conversion, spiritual support, problem-facing behavior, an information search for problem-solving, physical separation for emotional relaxation, avoidance, emotional aggressiveness and emotional expression. 3. Stress-coping behavior had a positive and significant correlation with the stress score(r = .4391, p= .000). In conclusion, the stress from school life was the most common experienced by all children. While independent effort in problem-solving was unsufficient, stress coping behavior had positive results. Therefore, this study verified the necessity of minimizing the stress children experience from school life and of helping them attain desirable stress-coping behaviors.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2004년도 추계학술대회
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• pp.1617-1622
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• 2004

Two-phase flow of liquid and gas through pipe lines are frequently encountered in nuclear power plant or industrial facility. Pressure waves which can be generated by a valve operation or any other cause in pipe lines propagate through the two-phase flow, often leading to severe noise and vibration problems or fatigue failure of pipe line system. It is of practical importance to predict the propagation characteristics of the pressure waves for the safety design for the pipe line. In the present study, a theoretical analysis is performed to understand the propagation characteristics of a weak shock wave in a bubbly flow. A wave equation is developed using a small perturbation method to analyze the weak shock wave through a bubbly flow with comparably low void fractions. It is known that the elasticity of pipe and void fraction significantly affect the propagation speed of shock wave, but the frequency of relaxation oscillation which is generated behind the shock wave is not strongly influenced by the elasticity of pipe. The present analytical results are in close agreement with existing experimental data.

• 동의신경정신과학회지
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• 제19권3호
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• pp.231-244
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• 2008

Insomnia is one of the highest frequency neuropsychosis of neuropsychiatry patients and is primarily caused by major depressive disorder. This case study is about a remedy for a 33 year-old woman who has insomnia and intense depressed mood caused by the continuous family jar. Also, she had the feeling of squeezing her body, pouring cold water into her body, anorexia and feeling cold and hot turn and turn. I operated mindfullness with accupuncture, herb-medication and aroma theraphy. Especially, mindfullness and Gagamguibi-tang were effective for relaxation and the sound sleep in quality and quantity. According to this study, the traditional oriental medical remedy such as accupuncture, herb-medication is effective for the cure of insomnia and mindfullness fortifies the oriental medical remedy.

• 폴리머
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• 제27권3호
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• pp.201-209
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• 2003

나일론의 종류에 따른 분쇄형 탄소 섬유/나일론 복합재료의 직류 및 교류 전도도, 그리고 전자기파 차폐 효율을 조사하였다. 탄소 섬유의 함량이 약 7 vol%에서 전도도가 급격하게 증가하는 percolation 전이가 관찰되었다. 나일론 46을 기저 수지로 하였을 경우 더욱 높은 전기 전도도를 나타냈으며, 계면 결합제의 적용 여부에 따라 전도도의 차이가 발생하였다. 온도증가에 따라 전도도가 증가하는 negative temperature coefficient 현상을 나타냈으며, percolation 전후의 탄소 섬유 함량에서의 주파수에 따른 전도기구를 완화와 공진 현상으로 각각 달리 설명할 수 있었다. 회로망 분석기를 통하여 측정한 전자기파 차폐 효율은 전도도 및 탄소 섬유의 함량에 따라 증가하였으며, 높은 전도도 영역에서의 전자기파 차폐 효율은 반사에 의한 차폐가 지배적이었다.

• 동의신경정신과학회지
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• 제16권2호
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• pp.181-188
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• 2005

The purpose of this study is to investigate how much acupuncture treatment and autogenic training can affect to physical, mental relaxation through neurofeedback(Alpha/Theta training). I measured the numerical value of Alpha/H-Beta on the patient with facial tremor due to anxiety during acupuncture treatment and autogenic training, and when that patient wasn't relaxed I gave her feedback. The result shows that autogenic training is always more effective than aucupuncture in making the patient relaxed. On this case, the symptom was not much improved after having the treatments 10 times, but the frequency and intensity of the tremor decresed little. In according to the number of treatments, relaxtion didn't ascend regularly. I think it depends on the patient's condition or surroundings. I am unsatisfied I had only one case in this study and the number of treatments wasn't enough. In the future, much more clinical and statistical studies on herbal, musical, aroma therapies should be needed.