• Journal of the Korea Institute of Military Science and Technology
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• v.10 no.2
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• pp.126-133
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• 2007

Lately, there exist growing demands to increase the firepower of mid-calibre automatic guns despite spatial limitations of armament. In this context, ammunitions of simple cylindrical shape are considered so advantageous that associated automatic guns are under development incorporating an intermittently rotating chamber mechanism. In this paper, relevant subsystems for such guns are to be described, and a digital controller to automate the entire system as well. Via dynamic simulations it proves to function well being able to drive the chamber at any constant speed up to 200spm, which is merely limited by the recoil performance. It is remarkable that the system synchronization idea in use is applicable to any other multi-actuator systems that should operate on the basis of event rather than time.

• Investigative Magnetic Resonance Imaging
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• v.3 no.1
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• pp.53-59
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• 1999

Purpose : To evaluate the usefulness of functional MR imaging (fMRI) for language mapping and determination of language lateralization. Materials and Methods : Functional maps of the language area were obtained during word generation tasks and decision task in ten volunteers (7 right handed, 3 left-handed). MR examinations were performed at 1.5T scanner with EPI BOLD technique. Each task consisted of three resting periods and two activation periods with each period of 30 seconds. Total acquisition time was 162 sec. SPM program was used for the postprocessing of images. Statistical comparisons were performed by using t-statistics on a pixel-by- pixel basis after global normalization by ANCOVA. Activation areas were topographically analyzed (p>0.001) and activated pixels in each hemisphere were compared quantitatively by lateralization index. Results : Significant activation signals were demonstrated in 9 of 10 volunteers. Activation signals were found in the premotor and motor cortices, the inferior frontal, inferior parietal, and mid-temporal lobes during stimulation tasks. In the right handed seven volunteers, activation of language areas was lateralized to the left side. Verb generation task produced stronger activation in the language areas and higher value of lateralization index than noun generation task or decision task. Conclusion : fMRI could be a useful non-invasive method for language mapping and determination of language dominance.

• Journal of Acupuncture Research
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• v.20 no.5
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• pp.187-207
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• 2003

Objective: Recently, many studies have showed the evidences of the effect of the acupuncture treatment through scientific methods. One of these methods is functional MRI. We performed electro-acupuncture on Liv3 and observed the change of brain activation using fMRI. Methods: To see the effect of electro-acupuncture stimulation on Liv3. the experiment was carried out on 12 healthy volunteers. using the gradient echo sequence with the 3.0T whole-body MRI system(ISOL). After the needle insertion on right Liv3. 2 Hz of electric stimulation was given for 30 seconds. repeated five times. with 30 seconds' intervals. The Image analysis including motion correction, talairach transformation. and smoothing was done with SPM99. Results : 1. Group averaged brain activation induced by bilateral electro-acupuncture stimulation on Liv3 activates Brodman Area 6, 13, 18, 19, 22, 31, 39, 44, 2. Group averaged brain deactivation induced by bilateral Electro-acupuncture stimulation on Liv3 activates Brodman Area 4, 6, 9, 19, 36, 37, 39. 3. Group averaged brain activation induced by unilateral(right side) electro-acupuncture stimulation on Liv3 activates Brodman Area 2, 3, 6, 9, 10, 22, 40, 42, 43. 4. Group averaged brain deactivation induced by unilateral(right side) electro-acupuncture stimulation on Liv3 activates Brodman Area 6, 18, 19, 28, 30, 31, 35, 37. 5. Brain region activated by motor stimulation activates Brodman Area 4, 6, 13, 19, 42.

• Journal of Acupuncture Research
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• v.20 no.4
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• pp.66-84
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• 2003

Objectve : Recent stuides suggested that there is a strong correlation between acupuncture stimulation and its cortical activation. Another study showed that either positive or negative BOLD effects could be observed depending on anatomical structure in acupuncture. Methods : 1) Subjects and paradigms: Two separate stimulation paradigms were performed in this study. To see the effects of electro-acupuncture stimulation on K7(Fuliu), the experiment was carried out on six healthy volunteers, using the gradient echo sequence with the 3.0T whole-body MRI system(ISOL). After the needle insertion on right K7(Fuliu), 2 Hz of electric stimulation was given for 30 seconds, repeated five times, with 30 seconds' intervals. During the intervals while there was no electro-stimulation, the subjects performed motor task as a reference. The image analysis including motion correction, talairach transformation, and smoothing was done using SPM99. Results: The electro-acupuncture stimulation on K7(Fuliu) activated Brodmann's Areas of 9, 19, 23, 24, 31, 32, 39 which may be the central pathways of the electro-acupuncture stimulation on K7(Fuliu) and those brain areas may be related with the function of the electro-acupuncture stimulation on K7(Fuliu).

• Journal of Acupuncture Research
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• v.20 no.3
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• pp.86-103
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• 2003

Objective : Recently, many studies have showed the evidences of the effect of the acupunture treatment through scientific methods. One of these methods is functional MRI. We performed electro-acupunture on Sp6 and observed the changes of brain activation using fMRI. Methods : To see the effect of electro-acupunture stimulation on Sp6, the experiment was carried out on 12 healthy volunteers, using the gradient echo sequence with the 3.0T whole-body MRI system(ISOL). After the needle insertion on right Sp6, 2Hz of electric stimulation was given for 30 seconds, repeated five times, with 30 seconds' intervals. The Image analysis including motion correction, talairach transformation, and smoothing was done with SPM99. Results : 1. Group averaged brain activation induced by bilateral eletro-acupunture stimulation on Sp6 activates Brodman Area 3, 7, 13. 2. Group averaged brain deactivation induced by bilateral eletro-acupunture stimulation on Sp6 activates Brodman Area 6, 38, 47. 3. Group averaged brain activation induced by unilateral(right side) eletro-acupunture stimulation on Sp6 activates Brodman Area 5, 6, 13, 17, 18, 19, 31, 38, 40 ptoms, back pain(32.5%) was the 4. Group averaged brain deactivation induced by unilateral(right side) eletro-acupunture stimulation on Sp6 activates Brodman Area 3, 4, 18, 21, 36, 38, 39. 5. Brain region activated by motor stimulation activates Brodman Area 3, 4, 6, 18, 19.

• The Korean Journal of Nuclear Medicine
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• v.39 no.6
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• pp.413-420
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• 2005

Purpose: Neuroreceptor PET studies require 60-120 minutes to complete and head motion of the subject during the PET scan increases the uncertainty in measured activity. In this study, we investigated the effects of the data-driven head mutton correction on the evaluation of endogenous dopamine release (DAR) in the striatum during the motor task which might have caused significant head motion artifact. Materials and Methods: $[^{11}C]raclopride$ PET scans on 4 normal volunteers acquired with bolus plus constant infusion protocol were retrospectively analyzed. Following the 50 min resting period, the participants played a video game with a monetary reward for 40 min. Dynamic frames acquired during the equilibrium condition (pre-task: 30-50 min, task: 70-90 min, post-task: 110-120 min) were realigned to the first frame in pre-task condition. Intra-condition registrations between the frames were performed, and average image for each condition was created and registered to the pre-task image (inter-condition registration). Pre-task PET image was then co-registered to own MRI of each participant and transformation parameters were reapplied to the others. Volumes of interest (VOI) for dorsal putamen (PU) and caudate (CA), ventral striatum (VS), and cerebellum were defined on the MRI. Binding potential (BP) was measured and DAR was calculated as the percent change of BP during and after the task. SPM analyses on the BP parametric images were also performed to explore the regional difference in the effects of head motion on BP and DAR estimation. Results: Changes in position and orientation of the striatum during the PET scans were observed before the head motion correction. BP values at pre-task condition were not changed significantly after the intra-condition registration. However, the BP values during and after the task and DAR were significantly changed after the correction. SPM analysis also showed that the extent and significance of the BP differences were significantly changed by the head motion correction and such changes were prominent in periphery of the striatum. Conclusion: The results suggest that misalignment of MRI-based VOI and the striatum in PET images and incorrect DAR estimation due to the head motion during the PET activation study were significant, but could be remedied by the data-driven head motion correction.

• Investigative Magnetic Resonance Imaging
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• v.7 no.2
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• pp.124-131
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• 2003

Purpose : To reveal clinical usefulness of functional MRI (fMRI) using sensorymotor and language stimuli for demonstrating anatomic relationship between sensorimotor or language cortices and lesions in the planning of brain tumor surgery. Materials and Methods : This study included 12 right-handed patients with brain tumors in or around sensorimotor or language cortices. Eleven patients were evaluated with primary motor and sensory stimuli. Of these patients, six patients were also evaluated with language stimuli. One patient was evaluated with language stimuli only. For fMR imaging, a 1.5T scanner was used and the EPI BOLD technique was employed. For postprocessing image, the SPM99 program and a program made by our department was utilized. We evaluated whether sensorimotor and language stimuli activate sensorimotor and language cortices. And also, clinical efficacy of revealing anatomic relationship between cerebral cortices and lesions for planning neurosurgical operation were evaluated. Finally, we compared post-operative neurologic function with pre-operative neurologic function in same patients. Results : The fMRI examination was successful in identifying the functional cortices and depicting anatomic relationship between functional cortices and lesions in all patients. In nine patients of 11 patients with identified sensorimotor cortices, postoperative grade of manual motor test was not changed, compared with preoperative grade. Whereas postoperative improved than preoperative grade in one patient of remaining two patients, postoperative aggravated than preoperative grade in the other. This result was due to atherosclerotic lacunar infarction, regardless of tumor resection. Postoperative deficit of language function was not found in seven patients with identified language cortices. Conclusion : fMRI could be a helpful method for determining the best approach to neurosurgical treatment in patients with brain tumors in or around sensorimotor or language cortices.

• Investigative Magnetic Resonance Imaging
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• v.9 no.1
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• pp.16-23
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• 2005

Purpose : In order to investigate the functional brain anatomy associated with mental calculation, functional magnetic resonance imaging was performed. Materials and Methods : In six normal right handed subjects, functional MR images were obtained using a 1.57 MR scanner and the EPI BOLD technique. The study included experiment I and experiment II. Each experiment consisted of five resting and four activation periods with each period of 30 seconds. During the activation period of both experiment I and II, calculation equations[an example: $(4+5)\times8=72$] were presented and the subjects were instructed to decide true or false of them. During the resting period of experiment I, the subjects were instructed to visually fixate on a crosshair. During the resting period of experiment II, two diagrams (an example: $(\bullet,\;\blacksquare)$)were presented and the subjects were instructed to decide they are same or not. For the post-processing of images, the SPM program was used, with the threshold of significance set at p<0.00001. The activated areas during the tasks were assessed. Results : In experiment 1, the inferior frontal gyrus, prefrontal cortex, promoter area, supplementary motor area, and intraparietal sulcus including superior parietal cortex were activated bilaterally. Although these areas were also activated in experiment II, the activated signals in the right frontal and parietal lobes were lessened. Conclusion : The left inferior frontal gyrus and prefrontal cortex and bilateral intraparietal sulci were activated during mental calculation. The right frontal and parietal lobes might be related to attention and decision making.

• The Korean Journal of Nuclear Medicine
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• v.32 no.3
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• pp.238-249
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• 1998

Purpose: To localize and compare the neural basis of verbal and visual human working memory, we performed functional activation study using $H_2^{15}O$ PET. Materials and Methods: Repeated $H_2^{15}O$ PET scans with one control and three different activation tasks were performed on six right-handed normal volunteers. Each activation task was composed of 13 match-ing trials. On each trial, four targets, a fixation dot and a probe were presented sequentially and subject's task was to press a response button to indicate whether or not the probe was one of the previous targets. Short meaningful Korean words, simple drawings and monochromic pictures of human faces were used as matching objects for verbal or visual memory. All the images were spatially normalized and the differences between control and activation states were statistically analyzed using SPM96. Results: Statistical analysis of verbal memory activation with short words showed activation in the left Broca's area, promoter cortex, cerebellum and right cingulate gyrus. In verbal memory with simple drawings, activation was shown in the larger regions including where activated with short words and left superior temporal cortex, basal ganglia, thalamus, prefrontal cortex, anterior portion of right superior temporal gyrus and right infero-lateral frontal cortex. On the other hand, the visual memory task activated predominantly right-sided structures, especially inferior frontal cortex, supplementary motor cortex and superior parietal cortex. Conclusion: The results are consistent with the hypothesis of the laterality and dissociation of the verbal and visual working memory from the invasive electrophysiological studies and emphasize the pivotal role of frontal cortex and cingulate gyrus in working memory system.

• Korean Journal of Acupuncture
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• v.31 no.1
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• pp.20-32
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• 2014

Objectives : There has been some controversy about the modulatory effects on brain function during acupuncture on each side of the same acupoint. This study was designed to investigate and compare the blood oxygen level-dependent(BOLD) responses of acupuncture on each side of ST36. Methods : Fourteen healthy subjects were recruited for imaging and received acupuncture or placebo stimulations either on the left or on the right acupoint of ST36 in each scan. For the voxel-wise statistical analysis, one sample T-test and the within-subject analysis of variance(ANOVA) test were performed using SPM8 software. Results : This study showed that acupuncture on each side of ST36 showed different BOLD signal patterns. Higher BOLD responses after acupuncture stimulations at the left ST36 compared to the right were observed mainly in the parahippocampal gyrus(BA 28), dorsolateral prefrontal cortex(DLPFC, BA 44), thalamus, culmen and claustrum. We investigated the different neural responses between rest and activation periods of placebo and acupuncture stimulations on each side of ST36. Acupuncture at the right ST36 elicited activation mainly in the insula, supplementary motor area(SMA) and anterior cingulate cortex(ACC), while acupuncture at the left ST36 elicited activation mainly in the insula, primary somatosensory cortex(SI, BA 2) and DLPFC(BA 44). Conclusions : To our knowledge, this is the first reported functional MRI study directly comparing when needling at the right and at the left side of ST36. This study's preliminary results proved to be evidence of acupuncture's different effects when performed on opposite sides of an acupoint.