• 대한전자공학회논문지TC
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• 제41권12호
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• pp.69-75
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• 2004

본 논문에서는 우수한 잡음 방지 성능과 다른 사용자 간섭에 강건하며, 보안성이 우수한 특징을 갖는 DS-UWB(Direct Sequence-UWB) 방식에 멀티밴드 방식을 적용하였다. 제안된 시스템의 각 서브밴드는 코히어런스 대역폭을 만족하지 못하기 때문에 각 서브밴드에서 레이크 수신기가 사용되었으며 레이크 수신기의 출력은 MRC(Maximum Ratio Combining) 기법을 사용하여 결합하였다. 제안된 시스템은 타 시스템과의 원활한 공존이 가능하며 PBI(Partial Band Interference)에 우수한 성능을 나타낸다. 또한 초광대역 안테나의 부담이 줄게 되며 평균전력 대비 첨두치(peak to average power) 값이 작다는 장점이 있다. 본 논문에서는 AWGN(Additive White Gaussian Noise), 다른 사용자 간섭 및 협대역 잡음이 존재하는 채널에서 멀티밴드 시스템을 적용한 DS-UWB 의 BER 을 수학적으로 분석하였으며, 수신단에서 서브밴드 수가 증가함에 따라 성능이 개선됨을 시뮬레이션을 통하여 입증하였다.

• The Journal of Korean Physical Therapy
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• 제27권2호
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• pp.85-88
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• 2015

Purpose: The purpose of this study was to investigate the effects of active abduction exercise of the great toe on the medial and lateral sesamoid bones in hallux valgus (HV) patients by measuring radiography. Methods: In this study 27 young subjects were separated into two groups (normal group and HV group). Two pictures were taken by radiography while maintaining resting and while holding maximal active abduction of the great toe in sitting position on an x-ray table. All radiographs were used to measure the distance of the medial and lateral sesamoid bone from the longitudinal axis of the first metatarsal bone, respectively. Paired t-test was used for analysis of the resting and active abduction exercise in groups. Independent t-test was used to evaluate statistical significance between normal group and HV group. The statistical significance level was p<0.05. Results: In active abduction exercise of the normal group, distance of the medial and lateral sesamoid bones was not significantly different compared to resting condition. In active abduction exercise of the HV group, change of distance of the medial and lateral sesamoid bones showed statistically significant difference compared to resting condition. The distance between the medial sesamoid bone showed a more significant decrease in the HV vs. normal group, while the distance between the lateral sesamoid bone was significantly greater in the HV vs. normal group. Conclusion: These findings suggest that active abduction exercises, to reduce or prevent deterioration of the HV angle, should be considered for sesamoid bone displacement to improve muscle balance in the great toe.

• 한국전문물리치료학회지
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• 제15권1호
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• pp.1-11
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• 2008

The purpose of this study was to assess the influence of two shoe size conditions on foot pressure, ground reaction force (GRF), and lower extremity muscle fatigue. Seven healthy men participated. They randomly performed walking and running in two different conditions: proper shoe size and 10 mm greater than proper shoe size. Peak foot pressure, and vertical, anterior and mediolateral force components were recorded with the Parotec system and Kisler force platform. To assess fatigue, the participants performed treadmill running for twenty-five minutes twice, each time wearing a different shoe size. Surface electromyography was used to confirm localized muscle fatigue using power spectral analysis of four muscles (tibialis anterior, gastrocnemius medialis, rectus femoris, and biceps femoris). The results were as follows: 1) In walking conditions, there was a significantly higher peak pressure in the 10 mm greater than proper shoe size insole sensor 1, 2, 14, and 18 (p<.05). 2) In running conditions, there was a significantly higher peak pressure in the 10 mm greater than proper shoe size insole sensor 5, 14, and 15 (p<.05). 3) In walking conditions, there was a significantly higher first maximal vertical GRF in the 10 mm greater than proper shoe size (p<.05). 4) In running conditions, no GRF components were significantly different between each shoe size condition (p>.05). 5) Muscle fatigue indexes of the tibialis anterior and rectus femoris were significantly increased in the 10 mm greater than proper shoe size condition. These results indicate that wearing shoes that are too large could further exacerbate the problems of increased foot pressure, vertical GRF, and muscle fatigue.

• Journal of Ecology and Environment
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• 제29권5호
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• pp.479-484
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• 2006

Ecophysiological parameters of non-transgenic sweetpotato (NT) and transgenic sweetpotato (SSA) plants were compared to evaluate their resistance to multiple environmental stresses. Stomatal conductance and transpiration rate in NT plants decreased markedly from Day 6 after water was withheld, whereas those values in SSA plants showed relatively higher level during this period. Osmotic potential in SSA plants was reduced more negatively as leaf water potential decreased from Day 8 after dehydration treatment, while such reduction was not shown in NT plants under water stressed condition. SSA plants showed less membrane damage than in NT plants. As water stress and high light stress, were synchronously applied to NT and SSA plants maximal photochemical efficiency of PS II ($F_v/F_m$) in NT plants markedly decreased, while that in SSA plants was maintained relatively higher level. This trend of changes in $F_v/F_m$ between SSA plants and NT plants was more conspicuous as simultaneously treated with water stress, high light and high temperature stress. These results indicate that SSA plants are more resistive than NT plants to multiple environmental stresses and the enhanced resistive characteristics in SSA plants are based on osmotic adjustment under water stress condition and tolerance of membrane.

• 농업과학연구
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• 제21권1호
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• pp.11-21
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• 1994

RNase를 강하게 분비하는 균을 젓갈류서 분리하여 호염성 Micrococcus sp.로 동정하였다. 선정균은 NaCl을 2M 함유하는 pH 7.0의 CM배지에서 $35^{\circ}C$로 2일간 배양할 때 생육이 가장 양호하였으며 yeast extract 2.0%, casamino acid 1.5%, NaCl 2.0M, pH 8.5의 배지에서 $35^{\circ}C$로 2일간 배양할 때 효소 생산이 최대였다. 조효소액을 유안 염석과 이온교환 크로마토그라피, gel 여과 등으로 정제한 결과 비활성이 98.8 units/mg, 정제도는 39.4배, 수율은 0.9% 이었다. 정제 효소의 작용 최적 pH는 8.0, 온도는 $55^{\circ}C$이었으며 RNA를 기질로 한 Km값은 5mg/ml이었다. NaCI농도에 따른 효소활성은 무첨가조건에서 가장 높았고 1.25M에서 활성이 소설되었다가 다시 증가되어 2.5M에서는 무첨가구의 45% 활성을 보였다.

• 한국동물학회지
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• 제36권3호
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• pp.425-432
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• 1993

Culex pipiens pallens에 존재하는 Alkaline phosphatase의 연구를 위한 적정 분석조건과 우화 후, 시간 경과에 따른 Alkaline phosphatase 활성 경향에 대해서 연구하였다. C. pipiens에 존재하는 Alkaline phosphatase의 활성은 우화 직후부터 지속적으로 감소하다가, 흡혈 자극에 의해서 급격하게 증가한다. 흡혈 후 30시간이 경과했을 때, 최대의 활성도를 보이고 감소하나, 흡혈 48시간 이후에는 다시 증가하여 지속적으로 유지됨을 알 수 있다. 기관별 분석에서 첫번째 활성 증가는 중장에서 일어나고, 두번째 활성 증가는 난소에서 일어남을 알 수 있다. 그리고 흡혈 후 30시간된 성체에서는 5개의 동위효소 밴드가 보이는데, 난소에서 ALP-1와 ALP-2가 나타나고, 가슴에서는 ALP-3, ALP-4와 ALP-5가 보인다. 지방체에서는 ALP-4와 ALP-5가, 중장에서는 ALP-3, ALP-4와 ALP-5가 나타남을 알 수 있다. 그리고 흡혈 후 72시간된 성체에서, ALP-1, ALP-2가 동일하게 존재함을 알 수 있다.

• 대한기계학회논문집A
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• 제37권1호
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• pp.89-95
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• 2013

본 연구에서 병렬형 매니퓰레이터는 두 개의 평행판 위를 움직이는 슬라이더와 말단장치가 임의로 조정될 수 있는 링크를 가지고 있고, 두 개의 슬라이더에 각각 연결된 링크는 커플링운동을 한다. 매니퓰레이터의 정기구학 및 역기구학 해석을 통하여 슬라이더의 위치 및 말단장치의 위치 사이의 관계식을 나타내는 변위방정식을 유도하고, 유도된 방정식으로부터 정기구학 및 역기구학의 자코비안 행렬들을 구한다. 이러한 행렬들을 이용하여 매니퓰레이터의 지역 성능지수를 제안한다. 성능지수의 시뮬레이션 결과로부터, 매니퓰레이터는 한 사분면에서만 원활한 운동을 할 수 있고, 링크 길이 비와 말단장치의 자세가 최대 성능지수가 분포하는 영역의 변화에 중대한 영향을 미친다.

• International Journal of Naval Architecture and Ocean Engineering
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• 제12권1호
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• pp.71-84
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• 2020

In order to improve the performance of marine centrifugal pump, a centrifugal pump whose specific speed is 66.7 was selected for the research. Outlet diameter D2, outlet width b2, blade outlet angle β2, blade wrap φ and blade number z of the impeller were chosen as the variables. The maximum weighted average efficiency and the minimum vibration intensity at the base were calculated as objectives. Based on the Latin Hypercube method, the impeller was numerically optimized. The numerical results show that after optimization, the amplitudes of pressure fluctuation on the main frequency at different monitoring points decrease in varying degrees. The radial force on impeller decreases obviously under off-design flow rates and is more symmetrical during the operation of the pump. The variation of the axial force is relatively small, which has no obvious relationship with the rotating angle of the impeller. The energy performance and vibration experiment was performed for verifying. The test results show that the weighted average efficiency under 0.8Qd, 1.0Qd and 1.2Qd increases by 4.3% after optimization. The maximal vibration intensity at M1-M4 on the pump base reduced from 0.36 mm/s to 0.25 mm/s, decreasing by 30.5%. In addition, the vibration velocities of bracket in pump side and outlet flange also have significant reductions.

• Physical Therapy Rehabilitation Science
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• 제9권4호
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• pp.287-294
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• 2020

Objective: This study aimed to investigate the effects of an ultrasound-based bar graph proportional to the quadriceps muscle thickness as a real-time visual feedback training tool in the elderly. Design: Cross-sectional study. Methods: Twenty-four elderly persons participated in this study and were randomly divided into three groups: oral training group (n=8, group 1), ultrasound imaging group (n=8, group 2), and graph group (n=8, group 3). In the pre condition, all participants performed maximal voluntary isometric contraction (MVIC) of the quadriceps with knee extension three times with oral training. In the post condition, group 1 performed MVIC of the quadriceps with oral training, group 2 performed MVIC of the quadriceps with real-time visual feedback using ultrasound imaging, and group 3 performed MVIC of the quadriceps with real-time visual feedback using a bar graph proportional to the quadriceps muscle thickness, three times for all groups. Muscle thickness, activity (mean, peak), tone, stiffness, logarithmic decrement, relaxation, and creep were measured in both conditions in all participants. Results: Visual feedback with a bar graph showed significant effects on muscle thickness, mean muscle activity, and peak muscle activity compared with oral training and visual feedback with ultrasound imaging (p<0.05). Conclusions: Isometric training of the quadriceps with real-time visual feedback using a bar graph proportional to the quadriceps muscle thickness may be more effective than other methods in improving muscle thickness and muscle activity. This study presented a tool that can help increase muscle thickness in the elderly.

• 대한본초학회지
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• 제28권3호
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• pp.7-15
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• 2013

Objectives : Interruption and subsequent restoration of blood flow into the kidney result in renal injury. As an approach to preventing the renal injury, we determined the optimal conditions and the underlying mechanisms by which supernatant of hot water extract of ground Triticum aestivum L. (extract) attenuated ischemia/reperfusion (I/R) injury. Methods : One hour after administration of the extract (400 mg/kg) by intraperitoneal injection, renal I/R injury was generated by clamping the left renal artery in rats after surgical removal of the right kidney, followed by reperfusion. The maximal difference between the vehicle-treated and the extract-treated group under ketamine/xylazine or enflurane anesthetization was assessed at varying periods of ischemia (30-45 min) and reperfusion (3-48 hr), based on the renal function assessed with serum creatinine levels, tissue injury with hematoxylin/eosin staining, and apoptosis with terminal deoxynucleotidyltransferase-mediated dUTP nick-end labeling staining. Results : Enflurane anesthetization with 40 min of ischemia and 24 hr of reperfusion was identified to be the optimal condition, under which condition serum creatinine levels and tubular damage in the extract-treated group were significantly reduced compared with those in the vehicle-treated group ($1.3{\pm}0.2$ versus $2.7{\pm}0.3$ mg/dL, P < 0.01, and average score $1.8{\pm}0.1$ versus $3.5{\pm}0.3$, P < 0.01, respectively). These beneficial effects were mediated by inhibition of apoptotic cascades through attenuation of renal tissue malondialdehyde levels, Bax/Bcl-2 ratio and caspase-3 levels. Conclusions : The extract conferred renal protection against ischemia/reperfusion injury in rats by scavenging reactive oxygen species and consequently blocking apoptotic cascades, plausibly augmented by enflurane protection.