• 한국인지과학회:학술대회논문집
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• 한국인지과학회 2005년도 춘계학술대회
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• pp.151-153
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• 2005

We investigated the brain substrate of repetition priming on the implicit memory taskusing low-resolution electromagnetic tomography (LORETA) with high-density 128 channel EEG and individual MRI as a realistic head model. Thirteen right-handed, healthy subjects performed a word/nonword discrimination task, in which the words and nonwords were presented visually,and some of the words appeared twice with a lag of one or five items. All of the subjects exhibited repetition priming with respect to the behavioral data, in which a faster reaction time was observed to the repeated word (old word) than to the first presentation of the word (new word). The old words elicited more positive-going potentials than the new words, beginning at 200 ms and lasting until 500 ms post-stimulus. We conducted source reconstruction using LORETA at a latency of 400 ms with the peak mean global field potentials and used statistical parametric mapping for the statistical analysis. We found that the source elicited by the old words exhibited a statistically significant current density reduction in the left inferior frontal gyrus. This is the first study to investigate the generators of repetition priming using voxel-by-voxel statistical mapping of the current density with individual MRI and high-density EEG.

• The Journal of Korean Physical Therapy
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• 제22권2호
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• pp.25-30
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• 2010

Purpose: Behavior and movement are accomplished by voluntary contractions of skeletal muscles. There are three types of muscle contractions: concentric, isometric and eccentric. The aim of our study was to determine whether there is a difference in the cortical activation pattern between concentric contraction and eccentric contraction of the wrist extensor muscle. Methods: Four healthy right-handed volunteers without any previous history of physical or neurological illness were recruited. fMRI scanning was done during 4 repeated blocks of concentric and eccentric exercise of the wrist joint. Subjects exercised for 12 seconds and then rested for 12 seconds before beginning the second set of exercises. To determine the excitability of cortical neurons during exercise, voxel count and intensity index were analyzed. Results: For right hand movements, when concentric contractions of the right wrist were done, only the left primary motor area was activated. In contrast, during eccentric contraction, both the primary motor area and secondary motor area were activated. For left hand movements, both concentric and eccentric contractions induced only the supplementary motor cortex and the contralateral primary motor cortex. Conclusion: During eccentric contractions, both the primary motor area and secondary motor area are activated in ipsilateral and contralateral brain areas. Thus, eccentric contractions require more complex and difficult movements than concentric contractions do.

• 한국운동역학회지
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• 제17권1호
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• pp.53-60
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• 2007

Recently tennis techniques has been changed in stance patterns. Stance is consist of square stance, open stance and semi-open stance. The purpose of this study was to analyze the kinematics variables of racket head velocity during forehand stroke by stance patterns. Eight high school tennis players were chosen for the study who use semi western grip right-handed person more than career 7 years. They performed horizontal swing and vertical swing that it was done each five consecutive trial in the condition of square, open and semi-open stance. The results showed that racket head velocity significant difference was not observed in stance types between swings at impact. Y and Z components of racket head velocity for horizontal and vertical swing at second prior to impact and at impact were that y components velocity was faster horizontal swing than vertical swing and z components velocity was later horizontal swing than vertical swing. Statistically significant variable to racket head velocity and Pearson's correlation were drawn as follows. 1. Z components of racket head velocity in square stance was significant correlation by right knee joint. 2. Y components of racket head velocity in semiopen stance was significant correlation by left hip joint. 3. Y components of racket head velocity in open stance was significant correlation by left ankle joint.

• Archives of Plastic Surgery
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• 제34권2호
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• pp.269-273
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• 2007

Purpose: High-pressure injection(HPI) injury is an injury caused by accidental injection of substances by industrial equipment. HPI injury of the hand is a serious injury that can be potentially devastating. There have been a number of publications on the results of its treatment and its functional outcome of these hands. Unfortunately, the clinical outcomes were unsatisfactory following an initial treatment approach of digital expression of the injection material, elevation, soaks, dressing changes, and antibiotics. Methods: A 43-year-old right handed man sustained a high pressure injection injury to the tip of the left index finger. The injected material was industrial paint thinner. Tissue necrosis was noted at the pulp of the finger. Several debridements and irrigation were required. A pedicled chest flap transfer was performed on the eighteenth day after injury as the dorsal nail complex remained viable. This is a retrospective review of our experience with high-pressure finger injection injury caused by paint. A literature review, retrospective chart and radiologic review were presented. Results: Follow-up length was about 1 year. The injuried hand was left nondominant hand, the index. Patient complaints were cold intolerance, paresthesia, contact pain, and impairment of activities of daily living. Conclusion: The outcome of high-pressure injection injuries of the hand is affected by many factors. The time between injury and operative treatment has been regarded as a key determinant by a number of authors. The nature of the injected material is probably more important. It has been noted by many authors that injuries with paints have a worse outcome than those with oil or grease. This study confirms the fact that high-pressure injection injury caused by paint thinner to the hand is a significant problem. Virtually a patient suffers sequelae of this injury. The injury has significant repercussions for future function and reintegration into the work force.

• Korean Journal of Radiology
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• 제1권1호
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• pp.19-24
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• 2000

Objective: In order to investigate the functional brain anatomy associated with verbal and visual working memory, functional magnetic resonance imaging was performed. Materials and Methods: In ten normal right handed subjects, functional MR images were obtained using a 1.5-T MR scanner and the EPI BOLD technique. An item recognition task was used for stimulation, and during the activation period of the verbal working memory task, consonant letters were used. During the activation period of the visual working memory task, symbols or diagrams were employed instead of letters. For the post-processing of images, the SPM program was used, with the threshold of significance set at p < .001. We assessed activated brain areas during the two stimulation tasks and compared the activated regions between the two tasks. Results: The prefrontal cortex and secondary visual cortex were activated bilaterally by both verbal and visual working memory tasks, and the patterns of activated signals were similar in both tasks. The superior parietal cortex was also activated by both tasks, with lateralization to the left in the verbal task, and bilaterally without lateralization in the visual task. The inferior frontal cortex, inferior parietal cortex and temporal gyrus were activated exclusively by the verbal working memory task, predominantly in the left hemisphere. Conclusion: The prefrontal cortex is activated by two stimulation tasks, and this is related to the function of the central executive. The language areas activated by the verbal working memory task may be a function of the phonological loop. Bilateral prefrontal and superior parietal cortices activated by the visual working memory task may be related to the visual maintenance of objects, representing visual working memory.

• 대한전자공학회논문지TC
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• 제47권5호
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• pp.69-74
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• 2010

본 논문에서는 CRLH 전송선을 이용하여 임의의 주파수 두 곳에서 저지 특성을 갖는 소형 이중대역 저지대역 여파기를 제안한다. 제안된 여파기는 CRLH 전송선을 단락된 병렬 스터브로 사용하였으며 CRLH 전송선의 비선형적인 위상응답을 이용하여 이중대역 저지 특성을 구현하였다. CRLH 전송선은 마이크로 스트립과 집중소자를 이용하여 구현되었다. 이 여파기는 작은 크기이며 저지되는 두 개의 주파수를 임의로 조정할 수 있다. 본 논문에서는 GPS대역과 ISM 대역을 저지하는 여파기를 설계하였으며 GPS대역에서는 -30dB, ISM대역에서는 약 -29dB 의 저지 특성을 확인하였다. 제작된 여파기의 크기는 10mm*15mm로 소형이다.

• 한국정보통신학회논문지
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• 제17권10호
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• pp.2233-2238
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• 2013

본 논문에서는 복합 좌/우향 (CRLH) 전송 선로를 이용하여 초광대역 필터의 새로운 설계 방법에 대해 나타내었다. CRLH 전송선로의 특성을 구현하기 위해 접지면에는 결함 접지면 구조(DGS)와 윗면에는 마이크로스트립 인터디지털 결합기를 이용하였다. 본 논문에서 제안하는 CRLH 전송선로는 저역통과 필터와 고역통과 필터의 특성을 결합한 특성을 나타내며 삽입손실이 적고 광대역 필터 특성을 얻을 수 있는 장점이 있다. 몇 개의 셀 구조에 대해 연구하였으며, 본 논문에서는 3-셀 구조의 UWB 필터를 설계하고 구현하였다. 실험결과와 시뮬레이션 결과가 일치하며 중심주파수 5 GHz에서 105 %의 대역폭을 나타내며 삽입손실은 중심주파수에서 0.7 dB를 나타내었다.

• Journal of electromagnetic engineering and science
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• 제14권1호
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• pp.15-24
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• 2014

A compact dual-band three-way metamaterial power divider is proposed that has three in-phase outputs. Fully printed composite rightand left-handed (CRLH) unequal and equal power dividers are first implemented for 900-MHz and 2.4-GHz bands with the power-division ratios of 2:1 and 1:1, respectively. An initial 1:1:1 power divider is then achieved by incorporating the input of the two-way equal block into an output of the unequal block, and trimming the interconnection parameters. The condition of an identical phase at the three outputs of the power divider is then met by devising a hybrid CRLH phase-shift line to compensate for the different phase errors at the two frequencies. This scheme is confirmed by predicting the performance of the power divider with circuit analysis and full-wave simulation and measuring the fabricated prototype. They results show agreement; the in-phase outputs as well as the desirable power-division are accomplished and outdo the conventional techniques.

• 전기학회논문지
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• 제59권8호
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• pp.1429-1435
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• 2010

In this paper, a double lorentz composite right left handed(DL-CRLH) transmission line is designed using defected ground structure (DGS) and varactor diodes. Previously, the diode has been adopted only selectively for one of parallel or series resonators, and the balanced frequency as well as triple band frequencies were fixed. However in the proposed DL-CRLH transmission line, the balanced frequency, where the resonant frequencies of the series-connected parallel resonator and shunt-connected series resonator are the same, is adjustable. In addition, the triple band frequencies are controlled, too. The measured balanced frequency varies between 3.42~4.8GHz according to the controlled bias voltage. Under the same bias condition for the balanced frequency, the adjusted frequencies are 2.22~2.77GHz, 3.7~5.2GHz, 7.32~8.23GHz, 3.42~4.8GHz, and 4.44~5.92GHz for the conditions that ${\beta}d=+0.5{\pi}$, $-0.5{\pi}$, 2nd $+0.5{\pi}$, ${\omega}_{\infty}$, and ${\omega}_o$, respectively.

• Journal of Electrical Engineering and Technology
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• 제10권2호
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• pp.653-658
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• 2015

This paper deals with an efficient optimization design method of a compact ultra wideband (UWB) filter which can improve the characteristics of the filter. The Evolution Strategy (ES) algorithm is adopted for the optimization and modified to suppress the ripple by inserting an additional step to the ES scheme. The algorithm has the ability to control the ripple of an insertion loss in a passband as a modified approach. During the modified ES, a structure of initial shape is changed a lot, while includes the stepped impedance (SI) and the composite right/left handed transmission line (CRLH-TL). And an optimized filter satisfies the UWB specifications on the stopband and passband with an acceptable insertion loss. The filter achieves a much developed shape, the size of $15{\times}14mm$, the 3dB bandwidth from 2.7 to 10.8GHz, the flat insertion-loss less than 1dB, the wide stopband with 12~20GHz, and an acceptable return loss.