• Korean Journal of Materials Research
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• v.28 no.1
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• pp.38-42
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• 2018

Continuous efforts are being made to improve the efficiency of Si solar cells, which is the prevailing technology at this time. As opposed to the standard front-lit solar cell design, the back-lit design suffers no shading loss because all the metal electrodes are placed on one side close to the pn junction, which is referred to as the front side, and the incoming light enters the denuded back side. In this study, a systematic comparison between the two designs was conducted by means of computer simulation. Medici, a two-dimensional semiconductor device simulation tool, was utilized for this purpose. The $0.6{\mu}m$ wavelength, the peak value for the AM-1.5 illumination, was chosen for the incident photons, and the minority-carrier recombination lifetime (${\tau}$), a key indicator of the Si substrate quality, was the main variable in the simulation on a p-type $150{\mu}m$ thick Si substrate. Qualitatively, minority-carrier recombination affected the short circuit current (Isc) but not the opencircuit voltage (Voc). The latter was most affected by series resistance associated with the electrode locations. Quantitatively, when ${\tau}{\leq}500{\mu}s$, the simulation yielded the solar cell power outputs of $20.7mW{\cdot}cm^{-2}$ and $18.6mW{\cdot}cm^{-2}$, respectively, for the front-lit and back-lit cells, a reasonable 10 % difference. However, when ${\tau}$ < $500{\mu}s$, the difference was 20 % or more, making the back-lit design less than competitive. We concluded that the back-lit design, despite its inherent benefits, is not suitable for a broad range of Si solar cells but may only be applicable in the high-end cells where float-zone (FZ) or magnetic Czochralski (MCZ) Si crystals of the highest quality are used as the substrate.

• The Journal of Korean Physical Therapy
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• v.24 no.2
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• pp.127-133
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• 2012

Purpose: This study aims to examine the power changes in eletrocenphalogram (EEG) detected from the tibialis anterior muscle, during repetitive contraction exercise in normal female adults. Methods: The subjects of this study were 24 normal adult females, with no musculoskeletal or nervous system disorders. The 24 female subjects were divided into two groups: 12 subjects comprised a voluntary stimulation training group, and the other 12 subjects comprised an electrical stimulation training group. A total of thirty contractions were made repetitively by each woman, with maximal voluntary contraction exercise for six seconds, and a resting time of three seconds. During the experiment, their EEG was measured at eight positions. The eight positions were Fpz, Fz, Cz, CPz, C3, C4, P3, and P4, in accordance with the international 10~20 system. Results: The relative alpha power and beta power showed no statistically significant differences between the two groups. But the relative gamma power of the CPz, C3, C4, P3, and P4 areas showed statistically significant differences between the two groups (p<0.05). The relative theta power of the C4 area showed statistically significant differences between the two groups (p<0.05). Conclusion: Our findings show that tibialis anterior muscle contraction by electrical stimulation and by voluntary repeated contraction differentially affected brain activation. In particular, the CPz, C3, C4, P3 positions of relative gamma power showed brain activation in voluntary contraction. The C4 position of relative theta power showed different brain activation between the two groups.

• Journal of the Korean Society of Physical Medicine
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• v.8 no.2
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• pp.281-287
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• 2013

PURPOSE: The study was designed to investigate the effects of visual, auditory, and visuoauditory cues on simple Serial Task Performance in heaithy adults. METHODS: Sixty-three right-handed heaithy adults without history of neurological dysfunction were participated. A modified version of the Serial Reaction Time Task (SRTT) using five blocks of perceptual motor sequences was administered. The blocked paradigm consisted of the five blocks with randomly repeated 8 digit sequences with 5 repetition. Three types of sensory cue were employed: visual cue, auditory cue and visuoauditory cue. All subjects were assigned to press the matched botton as quickly and accurately as possible, when one of 8 stimulations was presented(one, two, three, four, five, six, seven, eight). The reaction time, accuracy, and P300 latency were measured during serial task performance. The mean reaction time(ms), accuracy(%), and P300 latency(ms) were compared between three types of cue using ANOVA. RESULTS: The reaction time to auditory cue was significantly longer than visual and visuoauditory cues(p<.001). And accuracy to auditory cue was significantly lower than visual and visuoauditory cues(p<.001). All P300 latency(at Fz, Cz, Pz) were significantly longer than to visual and visuoauditory cues(p<.05). CONCLUSION: It is suggested that type of cues influence in choice reaction. These data may helpful in designing not only effective motor learning training programs for healthy persons but also reeducation programs for patients with neurological dysfunction.

• Korean Journal of Acupuncture
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• v.20 no.2
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• pp.31-46
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• 2003

Objectives : The aim of this study was to examine the effects of electroacupuncture(EA) at the BL60 (Kollyun) on normal humans using power spectral analysis. Methods : EEG power spectrum exhibit site-specific and state-related differences in specific frequency bands. In this study, power spectrum was used as a measure of complexity. 30 channel EEG study was carried out in 10 subjects $(10\;males;\;age=22.4{\pm}0.5$ years). Results : In alpha band, the power values at Fz during the non-acupoint treatment and at Fp2, T5 during the BL60-acupoint treatment significantly were decreased. In beta band, the power values at C3, Po2, O2, Oz during the BL60-acupoint treatment significantly were increased than the before-acupuncture treatment. In theta band, the power values at F7 during the BL60-acupoint treatment significantly was increased. However, the comparison with that before and after the treatment shows no significant differences in all channels.

• Journal of Life Science
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• v.18 no.12
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• pp.1775-1778
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• 2008

The purpose of this study was to compare the biomechanical difference of barefoot and two types taekwondo footwear. which will provide scientific data to coaches and players, to further prevent injuries and to improve each players skills. How to an effect on human body which studied a kinematics and kinetics from 8 college students during experiments. This study imposes several conditions by barefoot and two types of taekwondo footwear ran under average $3.82{\pm}0.59$ m/sec for kinetics analysis. The result of comparative analysis can be summarized as below. Friction coefficient analysis showed A Company shoes 0.60 and M Company shoes 0.61. Ground reaction force also showed that statically approximates other results from impact peak timing (p<0.001), Maximum loading rate (p<0.001), Maximum loading rate timing (p<0.001) and impulse of first 20 percent (p<0.001). Moment was M Company shoes bigger than A Company shoes to pronation moment and supination moment.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.02a
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• pp.402-402
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• 2012

최근 반도체 공정 중 fluorocarbon (CxHyFz) 가스와 함께 플라즈마 밀도가 큰 유도결합형 플라즈마을 사용한 식각장비가 많이 사용되고 있다. 특히 저 유전상수 값을 가지는 박막을 밀도가 큰 플라즈마와 함께 fluorocarbon 가스를 이용하여 식각을 하게 되면 매우 복잡한 현상이 생긴다. 따라서 식각률에 대한 모델을 세우고 적용하는 일이 매우 어렵다. 본 연구에서는 CF4가스를 Ar가스와 함께 혼합하고 기판 플라즈마와 유도결합형 플라즈마를 동시에 가진 식각장비를 사용하여, 저 유전상수 값을 갖는 박막을 식각하였다. 또한, 간단한 식각모델인 Langmuir adsorption model를 이용하여 식각률(Etch rate)에 대한 합리적인 이해를 얻기 위해, 기판과 유도결합형 플라즈마의 파워에 따른 식각률을 계산하고, 식각모델에서 사용되는 매개변수인 이온플럭스(Ion Flux)와 식각수율(Etch yield)을 연구하였다. 기판의 플라즈마 파워가 20에서 100 W 증가하면서 식각률이 269에서 478 nm/min로 증가하였으며, 식각수율이 0.4에서 0.59로 증가하는 것을 관찰하였다. 반면에 기판의 플라즈마 파워 증가에 따라 이온 플럭스는 3.8에서 $4.7mA/cm^2$로 변화가 크지 않았다. 또한, 유도결합형 플라즈마의 파워가 100에서 500 W 증가하면서, 식각률이 117에서 563 nm/min로 증가하였으며, 이온플럭스가 1.5에서 $6.8mA/cm^2$으로 변화하였다. 그러나, 식각수율은 0.46에서 0.48로 거의 변화하지 않았다. 그러므로 저 유전상수 값을 가지는 박막 식각의 경우, 기판의 플라즈마는 식각수율을 증가시키며 유도결합형 플라즈마는 이온 플럭스를 증가시켜 박막 식각에 기여하는 것으로 사료된다.

• Development and Reproduction
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• v.11 no.3
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• pp.141-153
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• 2007

The Wnt signaling pathway regulates cell proliferation and differentiation during development of multicellular organisms and plays pivotal roles in the maintenance of homeostasis in adult tissues. Therefore misregulation of Wnt signaling could be a pathogenesis of diverse human diseases such as cancers. Recently, the list of diseases that may be linked to the misregulation of Wnt signaling has exploded and more people are getting interested in the way of controlling Wnt signaling. There are a lot of review papers, however, since most of them have focused on specific issues for experts in Wnt signaling it may be difficult for new comers to understand the overall background and current status of Wnt signaling. In this review, we present data and interpretations for the overall processes of Wnt signal transduction to understand the past and current status of Wnt signaling.

• Journal of Pharmacopuncture
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• v.6 no.3
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• pp.91-106
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• 2003

Objectives : The aim of this study was to examine the effects of electroacupuncture(EA) at the PC6(Naegwan) and the TE5 (Oegwan) on nounal humans using power spectral analysis. Methods : EEG power spectrum exhibit site-specific and state-related differences in specific frequency bands. In this study, power spectrum was used as a measure of complexity. 30 channel EEG study was carried out in 30 subjects(30 males ; age=23.7 years). Results : In ${\alpha}$(alpha) band, the power values at F7 channels(p<0.05) during the PC6-acupoint treatment were significantly were decreased. In ${\beta}$(beta) band, the power values at Fp1, Fz, TT1, T5, P3, P4, Po1, P02, O1, Oz, O2 channels(p<0.05) during the non-acupoint treatment and at Fp1, F4, F8 channels(p<0.05) during the TE5-acupoint treatment significantly were increased. In ${\theta}$(theta) band, the power values at Fp1 channels(p<0.05) during the non-acupoint treatment and at Oz channels(p<0.05) the TE5-acupoint treatment significantly were increased. but, the power values at F7 channels(p<0.05) during the non-acupoint treatment were significantly were decreased. In ${\delta}$(delta) band, the power values at TCP1, TCP2, CP1, T5 channels(p<0.05) during PC6-acupoint treatment were increased and the power values at F7, TT2 channels(p<0.05) during non-acupoint treatment were increased. but, the power values at the TE5-acupoint treatment significantly was decreased than the before-acupuncture treatment.

• Physical Therapy Rehabilitation Science
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• v.6 no.2
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• pp.77-82
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• 2017

Objective: Swimming and water-based exercise (WE) programs can provide vigorous physical activity in a fun and a motivating environment. The properties of water, may make it easier for children with cerebral palsy (CP) to move and to participate in an WE program. The aims of this study was to evaluate the effect of WEs on postural control in children with spastic CP. Design: Quasi-experimental design (one group pretest-posttest design). Methods: Twenty preschoolers with spastic CP participated in this study. Prior to the application, sufficient warm-up training was performed to allow the subjects to adapt to the water. Afterwards, three different types of underwater leg exercises for the flexor, extensor, and adductor/abductor of muscles of the lower limb were performed. The WE program lasted during 8 weeks, with one-40 minute sessions per week (8 training session). The usual care was performed during the training session. The Korean-trunk control measurement scale (K-TCMS) and weight distribution variability (difference of both Fz) were measured before and after training session. Results: According to the results, the K-TCMS scores of the three sub-levels, including static sitting, dynamic sitting, and dynamic reaching, was significantly increased after the training session (p<0.05). Also, the weight distribution variability was significantly decreased after 8 weeks (p<0.05). Conclusions: We suggest that WEs may improve the postural control ability in children with spastic CP. Furthermore, we support the need for additional research on the effect of WE on gait or activity of daily living performance with a control group included.

• The Journal of the Korea Contents Association
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• v.14 no.9
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• pp.131-140
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• 2014

The purpose of this study was to kinetic analysis of using the skill of breathing korean dance movement will be to perform. To achieve the research objectives cheoyongmu Nakhwayousu the operation was performed. The selection of subjects like the following: Five people were skilled use of breathing and five unskilled person. The results are as follows. The skilled and the unskilled were no significant differences in the duration time. And the skilled and the unskilled z-axis position of the center of mass, there was a significant difference (p<.05). The skilled and the unskilled y-axis velocity of the center of mass, there was a significant difference of event 1 and event 4 (p<.05). And z-axis velocity of the center of mass, there was a significant difference of event 3 (p<.05). And the skilled and the unskilled Fx of GRF, there was a significant difference of event 2 and event 4 (p<.05). And Fy of GRF, there was a significant difference of event 1 and event 5 (p<.05). And Fz of GRF, there was a significant difference of event 4 (p<.05).