• 전자공학회논문지D
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• 제35D권2호
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• pp.33-39
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• 1998

A six-beam accelerometer with self-compensated off-axis sensitivity was fabricated onthe selectively diffused (111)-oriented n/n$^{+}$/n silicon substrates by a unique porous silicon micromachining technique, which has self-stip characteristics and highly seletive formation of porous silicon layer during anodic reaction. Also, the characteristics of the fabricated accelerometer were investigated. The sensitivity of the acceleormeter added up outputs of three bridges through a summing circuit was 0.68 mV/g and the nonlinearity was less than 2% of the full scale output. The measured first resonant frequency was 4.236 kHz. When the outputs of three bridges were compared to summing output of bridges obtained through summing circuit, the normal output for Z-axis acceleration exhibited the same value s summing outputs of three bridges without reduction of sensitivity and thus the sensitivity decrease due to additional beam was compensated. Although a maximum off-axis sensitivity in one bridge of the accelerometer showed 17% of normal sensitivity, the off axis sensitivity obtained from summing output of three bridges decreased to 1.0%. Therefore, the self-elimination of off-axis sensitivity can be simply realized by obtaining the output of the sensor through summing circuit.t.

• 한국소음진동공학회논문집
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• 제18권7호
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• pp.764-774
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• 2008

A fire-out-of-battery(FOOB) mechanism, which is a new recoil technology, can reduce dramatically the level of a recoil force compared to the conventional recoil system. The FOOB mechanism pre-accelerates the recoil parts in direction opposite of conventional recoil before ignition. This momentum of the recoil parts due to pre-acceleration can reduce the firing impulse. In this paper, the dynamics of the recoil system with this FOOB mechanism is formulated and simulated numerically. The results of the simulation show that the FOOB system can reduce the recoil force and stroke compared to the conventional system under normal condition. When the fault modes happen, the FOOB system may not perform well and may be damaged seriously due to excessive recoil force and stroke. Hence, the control of the fault modes is necessary to achieve the normal operation of the FOOB system. The results that an additional MR damper enables the FOOB system to perform well under all firing condition.

• 대한한방내과학회지
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• 제28권2호
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• pp.377-384
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• 2007

Objective : Immune potentiation including activation of T cells, B cells, macrophages, and dendritic cells is known to play a key role in prevention and treatment of patients with cancer. In this study, we investigated the effects of Acanthopanax sessiliflorus (AR) on the immune system, especially on thymocytes, splenocytes, and macrophages. Methods : We investigated the effects of AR on proliferation of splenocytes in normal mice, and the effects on proliferation of splenocytes and thymocytes in tumor-bearing mice. In addition, the effect of AR on NO production using macrophages was investigated. Results : Treatment with AR accelerated proliferation of splenocytes in vitro. AR also accelerated thymocyte proliferation, but did not affect splenocytes proliferation in normal mice. In contrast, AR accelerated proliferation of splenocytes and thymocytes significantly in tumor bearing mice. In addition, NO production level from macrophages was elevated by treatment with AR. Conclusion : These results demonstrate that AR has anti-cancer activities and related mechanisms are involved in immune potentiation such as acceleration of immune cell proliferation and elevation of NO production level in macrophages. In addition, we also demonstrate the possibilities of AR as complementary and alternative medicine to standard anti-cancer drugs.

• 디지털콘텐츠학회 논문지
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• 제16권1호
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• pp.63-70
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• 2015

본 연구는 PACS의 영상저장부의 디스크 배열에 들어가는 하드디스크의 수명을 제조회사의 가속 수명시험 결과로 예측하고자 하였다. $50^{\circ}C$, $60^{\circ}C$의 고장시간 데이터로 Anderson-Darling 적합도 검증을 진행하여 와이블 분포를 채택하였다. 형상모수와 척도모수로 동일성 검증을 진행한 결과, 가속 수명 시험 $50^{\circ}C$ 조건과 가속 수명 시험 $60^{\circ}C$ 조건의 확률분포가 통계적으로 유의하지 않았다. 온도 가속인자를 포함한 와이블-아레니우스 모형으로부터 추정한 형상모수는 1.0409이며, 사용조건($30^{\circ}C$)의 특성수명은 24603.5 시간이었다. 또한 아레니우스 모델 식에 반영하여 활성화 에너지 0.5011 eV을 산출하였다. 그리고 가속시험의 정확성 확보차원에서 가속시험 불량시료와 시장 반품 시료로 고장 분석을 진행한 결과, 불량 모드별 점유율의 세부 차이는 있으나, 점유율 순서는 일치 하였다. 본 연구는 PACS 환경 하에서 하드디스크의 가속시험절차를 제안하며, 제조자와 사용자간에 수명예측에 도움을 주고자 한다.

• Archives of Plastic Surgery
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• 제38권6호
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• pp.765-774
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• 2011

Purpose: Many facial burn patients suffer from hyperpigmentation and its treatment has been challenging. Vitamin C (ascorbic acid) has important physiologic effects on skin, including inhibition of melanogenesis, promotion of collagen biosynthesis, prevention of free radical formation, and acceleration on wound healing. The purpose of this study is to evaluate the effectiveness of Vitamin C iontophoresis for the treatment of postburn hyperpigmentation. Methods: The authors performed a retrospective analysis of 93 patients who were admitted for the treatment of facial burn from February 2008 through February 2010. Among them, 51 patients were treated with Vitamin C iontophoresis to control postburn hyperpigmentation and 42 patients were not. Experimental group was chosen 20 of 51 patients who had been treated with Vitamin C iontophoresis and had normal facial skin on the comparable contralateral aesthetic unit. Control group was chosen 20 of 42 patients who were not treated with Vitamin C iontophoresis and had also contralateral normal aesthetic unit. The resulting color of 20 patients who were treated with Vitamin C iontophoresis was compared with the color of the contralateral normal facial skin using a digital scale color analysis. Results were analyzed with Wilcoxon signed rank test. Results: The analysis revealed significant improvement of hyperpigmentation in the experimental group compared to control group. The difference of intial value and the value in 6 months showed significant change. Mean (${\Delta}^{initial}$-${\Delta}^{6month}$) of experimental group was 11.61 and control group was 7.23. Thus, the difference between the experimental group and the control group was 4.38. Therefore, Vitamin C iontophoresis revealed significant improvement of hyperpigmentation in the experimental group compared with control group. Conclusion: Vitamin C iontophoresis is an effective treatment modality for postburn hyperpigmentation.

• Structural Engineering and Mechanics
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• 제23권6호
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• pp.615-634
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• 2006

Seismic response of the liquid storage tanks isolated by the elastomeric bearings and sliding systems is investigated under near-fault earthquake motions. The fault normal and parallel components of near-fault motion are applied in two horizontal directions of the tank. The continuous liquid mass of the tank is modeled as lumped masses known as sloshing mass, impulsive mass and rigid mass. The corresponding stiffness associated with these lumped masses has been worked out depending upon the properties of the tank wall and liquid mass. It is observed that the resultant response of the isolated tank is mainly governed by fault normal component with minor contribution from the fault parallel component. Further, a parametric study is also carried out to study the effects of important system parameters on the effectiveness of seismic isolation for liquid storage tanks. The various important parameters considered are: aspect ratio of tank, the period of isolation and the damping of isolation bearings. There exists an optimum value of isolation damping for which the base shear in the tank attains the minimum value under near-fault motion. The increase of damping beyond the optimum value will reduce the bearing and sloshing displacements but increases the base shear. A comparative performance of five isolation systems for liquid storage tanks is also studied under normal component of near-fault motion and found that the EDF type isolation system may be a better choice for design of isolated tank in near-fault locations. Finally, it is also observed that the satisfactory response can be obtained by analysing the base-isolated tanks under simple cycloidal pulse instead of complete acceleration history.

• 한국전문물리치료학회지
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• 제14권4호
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• pp.44-49
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• 2007

The purpose of this study was to investigate the effects of auditory cues in the form of a metronome on gait initiation (GI) in Parkinson's disease (PD). 2 patients (mean age: 54 yrs) with idiopathic PD participated in the study. All patients (Hoehn and Yahr disability score of 2.0) were tested in the "on" state approximately 1.5 hours following the administration and fully responding to their PD medications. Subjects first initiated walking at self-initiated speeds to determine their cadences. Then, subjects were asked to initiate gait along the walkway while keeping pace with a metronome. The metronome rate (in beats/min) was set at a cadence 85% (slow condition), 100% (normal condition) and 115% (fast condition) of gait for each subject. Subjects were able to increase the speed of GI with faster cadence, but the speed of GI for the slow condition was similar to that of the normal condition. Swing toe-off was 578.3 ms for the fast condition, 709.4 ms for the normal condition and 736.2 ms for the slow condition. Respective times for swing heel-strike were 894.3 ms, 1110.2 ms and 1119.1 ms, and stance toe-off were 1105.4 ms, 1338.5 ms, and 1343.1 ms. Except for stance unloading ground reaction forces were greatest for the fast condition and smallest for the slow condition. It appears that PD patients were able to modulate GRFs and temporal events in response to auditory cues to achieve the peak acceleration force of the swing and stance limb. The findings from this study provided preliminary data, which could be used to investigate how PD patients modulate GRFs and temporal events during GI in response to tasks.

• 한국전문물리치료학회지
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• 제14권4호
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• pp.66-74
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• 2007

The aim of the present study was to investigate age-related differences in stepping behavior in response to sensory perturbations of postural balance. The participants for this study were 2 healthy elderly adults (mean age=76.0) and 2 younger adults (mean age=25.5). Subjects were asked to step over a 10 cm high obstacle at self-paced speed with the right limb to land on the primary target (normal step length) that is 10 cm in diameter. However, if, during movement, the light was illuminated, then the subject had to step on the secondary target (long step length). It was planned that the onset of the light would be prior to peak Fx of swing limb, between swing peak Fx and swing toe-off, and after swing toe-off. In the younger adults these secondary visual cues were provided at mean times of 240 ms (standard deviation (SD)=11), 402 ms (SD=13), and 476 ms (SD=88) following the movement onset. Corresponding mean times for the healthy elderly were 150 ms (SD=67), 352 ms (SD=39), and 562 ms (SD=115). Results showed great changes in both group and visual cue condition in Fx ground reaction forces and temporal events following the swing toe-off. Swing limb acceleration force (Fx) and stance peak Fx1 was much greater in the young adults compared to the older adults. Both young and older adults increased stance peak Fx2 in the visual cue condition compared to normal stepping. There was no difference in stance peak Fx2 between the visual cue conditions in both groups. Similarly, the time to stance peak Fx2 was much longer for the visual cue condition than for the normal stepping. It was not different between the visual cue conditions in the young adults, but in the elderly mid and late cue was much greater than early cue. In addition, time to stance peak Fx2 and swing and stance time were much longer in the older adults compared to the young adults for the visual cue conditions. These results suggest that unlike young adults, elderly adults did not flexibly modify their responses to unexpected changes in step length while stepping over obstacles.

• 한국전기전자재료학회논문지
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• 제33권3호
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• pp.231-238
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• 2020

This paper investigates the soundness of porcelain insulators associated with the acoustic emission (AE) technique. The AE technique is a popular non-destructive method that measures and analyzes the burst energy that occurs mainly when a crack occurs in a high-frequency region. Typical AE methods require continuous monitoring with frequent sensor calibration. However, in this study, the AE technique excites a porcelain insulator using only an impact hammer, and it applies a high-pass filter to the signal frequency range measured only in the AE sensor by comparing the AE and the acceleration sensors. Next, the extracted time-domain signal is analyzed for the damage assessment. In normal signals, the duration is about 2ms, the area of the envelope is about 1,000, and the number of counts is about 20. In the damage signal, the duration exceeds 5ms, the area of the envelope is about 2,000, and the number of counts exceeds 40. In addition, various characteristics in the time and frequency domain for normal and damage cases are analyzed using the short-time Fourier transform (STFT). Based on the results of the STFT analysis, the maximum energy of a normal specimen is less than 0.02, while in the case of the damage specimen, it exceeds 0.02. The extracted high-frequency components can present dynamic behavior of crack regions and eigenmodes of the isolated insulator parts, but the presence, size, and distribution of cracks can be predicted indirectly. In this regard, the characteristics of the surface crack region were derived in this study.

• 한국전산유체공학회지
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• 제12권1호
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• pp.1-8
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• 2007

A code is developed using the hybrid Cartesian/immersed boundary method and it is applied to simulate flows around a three-dimensional deforming body. A new criterion is suggested to distribute the immersed boundary nodes based on edges crossing a body boundary. Velocities are reconstructed at the immersed boundary nodes using the interpolation along a local normal line to the boundary. Reconstruction of the pressure at the immersed boundary node is avoided using the hybrid staggered/non-staggered grid method. The developed code is validated through comparisons with other experimental and numerical results for the velocity profiles around a circular cylinder under the forced in-line oscillation and the pressure coefficient distribution on a sphere. The code is applied to simulate the flow fields around a plate whose tail is periodically flapping under a translation. The effects of the velocity and acceleration due to the deformation on the periodic shedding of pairs of tip vortices are investigated.