• The Korean Journal of Physiology and Pharmacology
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• v.17 no.5
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• pp.393-403
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• 2013

Baicalein (BA), a plant-derived active flavonoid present in the root of Scutellaria baicalensis, has been widely used for the treatment of stress-related neuropsychiatric disorders including depression. Previous studies have demonstrated that repeated restraint stress disrupts the activity of the hypothalamic-pituitary-adrenal (HPA) axis, resulting in depression. The behavioral and neurochemical basis of the BA effect on depression remain unclear. The present study used the forced swimming test (FST) and changes in brain neurotransmitter levels to confirm the impact of BA on repeated restraint stress-induced behavioral and neurochemical changes in rats. Male rats received 10, 20, or 40 mg/kg BA (i.p.) 30 min prior to daily exposure to repeated restraint stress (2 h/day) for 14 days. Activation of the HPA axis in response to repeated restraint stress was confirmed by measuring serum corticosterone levels and the expression of corticotrophin-releasing factor in the hypothalamus. Daily BA administration significantly decreased the duration of immobility in the FST, increased sucrose consumption, and restored the stress-related decreases in dopamine concentrations in the hippocampus to near normal levels. BA significantly inhibited the stress-induced decrease in neuronal tyrosine hydroxylase immunoreactivity in the ventral tegmental area and the expression of brain-derived neurotrophic factor (BDNF) mRNA in the hippocampus. Taken together, these findings indicate that administration of BA prior to the repeated restraint stress significantly improves helpless behaviors and depressive symptoms, possibly by preventing the decrease in dopamine and BDNF expression. Thus, BA may be a useful agent for the treatment or alleviation of the complex symptoms associated with depression.

• Journal of Biomedical Engineering Research
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• v.34 no.4
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• pp.182-188
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• 2013

This study aims to develop a practical algorithm which can detect freezing of gait(FOG) in patients with Parkinson's disease(PD). Eighteen PD patients($68.8{\pm}11.1yrs.$) participated in this study, and three($68.7{\pm}4.0yrs.$) of them showed FOG. We suggested two time-domain algorithms(with 1-axis or 3-axes acceleration signals) and compared them with the frequency-domain algorithm in the literature. We measured the acceleration of left foot with a 3-axis accelerometer inserted at the insole of a shoe. In the time-domain method, the root-mean-square(RMS) acceleration was calculated in a moving window of 4s and FOG was defined as the periods during which RMS accelerations located within FOG range. The parameters in each algorithm were optimized for each subject using the simulated annealing method. The sensitivity and specificity were same, i.e., $89{\pm}8%$ for the time-domain method with 1-axis acceleration and were $91{\pm}7%$ and $90{\pm}8%$ for the time-domain method with 3-axes acceleration, respectively. Both performances were better in the time-domain methods than in the frequency-domain method although the results were statistically insignificant. The amount of calculation in the time-domain method was much smaller than in the frequency-domain method. Therefore it is expected that the suggested time domain algorithm would be advantageous in the systematic implementation of FOG detection.

• The korean journal of orthodontics
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• v.31 no.1 s.84
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• pp.15-24
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• 2001

In order to achieve a desirable tooth movement, it is of great importance to control the M/F ratio and to know the location of the center of resistance. The purpose of this study was to locate the center of resistance and the axis of rotation, and to estimate the stress distribution in the periodontal ligament with experimental model. After preparing a model of an upper canine with a simulated periodontal ligament and alveolar bone, the force and moment were applied. The tooth movement was traced using measuring device with LVDTs(Linear variable differential transformers) that can measure three dimensional tooth movement in real time. The results were as follows. 1. The location of center of resistance by transverse force was $29\%$ of root length measured from alveolar crest to apex regardless of force magnitude. The position of the center of resistance is more coronal than that of two-dimensional model($42\%$). 2. The center of resistance and the axis of rotation coincide when couple moment was applied. 3. As the magnitude of moment increases, tooth tends to extrude irrespective of the direction of the moment. 4. The relationship between location of force and axis of rotation (a x b = $49.6\;mm^2$) was obtained. A tooth movement can be predicted through this formula. 5. The centers of rotation by transverse force were plotted linearly.

• Journal of Power Electronics
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• v.15 no.3
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• pp.721-729
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• 2015

A sensorless control method was recently investigated in the robot and automation industry. This method can solve problems related to the rise of manufacturing costs and system volume. In a vector control method, the rotor position estimated in the sensorless control method is generally used. This study is based on a conventional full-order flux observer. The proposed full-order flux observer estimates both currents and fluxes. Estimated d- and q-axis currents and fluxes are used to estimate the rotor position. In selecting the gains, the proposed full-order flux observer substitutes gain k for the speed information in the denominator of the gain for fast convergence. Therefore, accurate speed control in a low-speed region can be obtained because gains do not influence the estimation of the rotor position. The stability of the proposed full-order flux observer is confirmed through a root-locus method, and the validity of the proposed observer is experimentally verified using a surface permanent-magnet synchronous motor.

• Journal of Welding and Joining
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• v.27 no.5
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• pp.62-67
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• 2009

Welding deformation during the assembly process is affected by not only local shrinkage due to rapid heating and cooling, but also root gap and misalignment between parts to be welded. Therefore, the prediction and control of welding deformation have become of critical importance. In this study, it was focused on the development of the 3-axis apparatus for real-time measurement of the welded deformation. To achieve the objective, a D-H algorithm has been carried out to check the behavioral and performance evaluation for the developed robot. The sequence experiments were taken the base materials of $400{\times}200{\times}4.5mm$ plate for butt welding. The real-time experimental measurements are in good agreement with the measured results.

• The Bulletin of The Korean Astronomical Society
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• v.40 no.2
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• pp.56.4-57
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• 2015

We present the optical design and a sensitivity analysis for a wide field of view (FOV) instrument operating at UV and IR wavelengths. The ongoing investigation is performed in collaboration with Omnisys Instruments (Sweden) and focuses on a telluric-limb-viewing instrument that will fly in a low Earth orbit to study mesospheric wave structures over a wide range of horizontal scales in the altitude range 80 - 100 km. The instrument has six wavelength channels which consist of 4 channels of IR and 2 of UV. We are proposing an optical design based on three mirror aplanatic off-axis reflective system. The entrance pupil diameter and effective focal length are 45 mm and 270 mm, respectively. The FOV is $5.5^{\circ}{\times}1^{\circ}$ and the secondary mirror is set for stop. The optical specification is required to have an encircled energy of at least 80 % within a diameter of 21 um. We performed sensitivity analysis for the longest wavelength of 772 nm in consideration of the diffraction limit of system. The results show that tolerance limits for positions and angles of the mirrors are not very sensitive compared with typical error budgets of manufacturing and assembling process. The secondary mirror has the most sensitive tolerance for surface figure of 250 nm in root-mean-square.

• The Bulletin of The Korean Astronomical Society
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• v.40 no.2
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• pp.56.2-56.2
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• 2015

본 연구에서는 미국 맥도날드 천문대 (Mcdonald Observatory)에 있는 82인치 Otto Struve 망원경의 가이드 망원경으로 사용하기 위해 2개의 반사경을 이용해 구경이 100 mm이고 유효초점거리가 800 mm인 비축 반사망원경을 설계하였다. 비축 반사경은 일반적인 축 대칭인 반사경보다 가공이 매우 어렵기 때문에 형상 정밀도의 요구량을 알 수 있다면 비축 반사경을 가공하는 과정에서 시간과 비용을 절약할 수 있다. 광학계가 수차가 잘 보정된 회절한계의 성능이기 때문에 엔서클드 에너지 직경(Encircled Energy Diameter) 분석을 통해 민감도 분석을 하였다. 광학설계 소프트웨어인 CodeV를 사용하여 80 % 에너지가 $20{\mu}m$ 내에 들도록 공차한계로 설정하였으며, 기준 파장은 $587.56{\mu}m$이다. 또한 부경과 초점 면 사이의 거리를 보상자로 설정하여 공차가 광학계의 성능에 미치는 영향을 최소화하였다. 민감도 분석은 반사경의 위치, 회전, 그리고 반사경의 형상 정밀도에 대해 수행하였다. 분석 결과, 반사경의 위치와 각도는 일반적인 제작 및 조립 공차보다 매우 작은 것을 확인하였다. 그리고 형상정밀도는 주경이 부경보다 민감하였으며 자승 제곱 평균제곱근 (root-mean-square) 32 nm로 가장 민감한 결과가 나왔다.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.15 no.3
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• pp.21-27
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• 2016

The static and dynamic structural integrity qualification was performed through the seismic analysis of a small-size Savonius-type vertical wind turbine at dead weight plus wind load and seismic loads. The ANSYS finite element program was used to develop the FEM model of the wind turbine and to accomplish static, modal, and dynamic frequency response analyses. The stress of the wind turbine structure for each wind load and dead weight was calculated and combined by taking the square root of the sum of the squares (SRSS) to obtain static stresses. Seismic response spectrum analysis was also carried out in the horizontal (X and Y) and vertical (Z) directions to determine the response stress distribution for the required response spectrum (RRS) at safe-shutdown earthquake with a 5% damping (SSE-5%) condition. The stress resulting from the seismic analysis in each of the three directions was combined with the SRSS to yield dynamic stresses. These static and dynamic stresses were summed by using the same SRSS. Finally, this total stress was compared with the allowable stress design, which was calculated based on the requirements of the KBC 2009, KS C IEC 61400-1, and KS C IEC 61400-2 codes.

• Bulletin of the Korean Space Science Society
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• 2011.04a
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• pp.28.3-28.3
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• 2011

Halo coronal mass ejections (HCMEs) are mainly responsible for the most severe geomagnetic storms. To minimize the projection effect of the HCMEs observed by coronagraphs, several cone models have been suggested. These models allow us to determine the geometrical and kinematic parameters of HCMEs : radial speed, source location, angular width, and the angle between the central axis of the cone and the plane of the sky. In this study, we compare these parameters form two representative cone models (the ice-cream cone model and the asymmetric cone model) using well-observed HCMEs from 2001 to 2002. And we obtain the root mean square error (rms error) between observed projection speeds and calculated projection speeds for both cone models. It is found that the average rms speed error (89 km/s) of the asymmetric cone model is a little smaller than that (107 km/s) of the ice-cream cone models, implying that the radial speeds from both models are reasonably estimated. We also find that the radial speeds obtained from two models are similar to each other with the correlation coefficient of about 0.8.

• Journal of Pharmacopuncture
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• v.6 no.2
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• pp.159-164
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• 2003

Results : 1. The most important concept of IMS is chronic pain illness that may develop into hypersensitivity of the nerves, i.e., neuropathy. 2. Muscle shortening may be triggered by stress, including emotional, physical, external, and internal factors. 3. Muscle shortening increases mechanical tension on the muscles as well as inducing abrasion of the tissues by stretching ligament, tendon, cartilage, bone, and etc. 4. Pain from neuropathy is normally manifested on musculoskeletal system and spasm or shortening play as the central axis of this pain. 5. Neuropathy often appears at the nerve root level and the most important decisive factor of radiculopathy is muscle shortening. 6. Spondylosis is the most common cause of radiculopathy. 7. The most significant treatment principle of IMS is to relieve muscle shortening and remove stimulating determinant from the vertebrae. 8. Dry needling is quite effective for treating various pain caused by muscle shortening.