• Proceedings of the Korean Vacuum Society Conference
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• 2012.08a
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• pp.174-175
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• 2012

(In, Ga) N-based III-nitride semiconductor materials have been viewed as the most promising materials for the applications of blue and green light emitting devices such as light-emitting diodes (LEDs) and laser diodes. Although the InGaN alloy can have wide range of visible wavelength by changing the In composition, it is very hard to grow high quality epilayers of In-rich InGaN because of the thermal instability as well as the large lattice and thermal mismatches. In order to avoid phase separation of InGaN, various kinds of structures of InGaN have been studied. If high-quality In-rich InGaN/GaN multiple quantum well (MQW) structures are available, it is expected to achieve highly efficient phosphor-free white LEDs. In this study, we proposed a novel InGaN double hetero-structure grown on GaN nano-pyramids to generate broad-band red-color emission with high quantum efficiency. In this work, we systematically studied the optical properties of the InGaN pyramid structures. The nano-sized hexagonal pyramid structures were grown on the n-type GaN template by metalorganic chemical vapor deposition. SiNx mask was formed on the n-type GaN template with uniformly patterned circle pattern by laser holography. GaN pyramid structures were selectively grown on the opening area of mask by lateral over-growth followed by growth of InGaN/GaN double hetero-structure. The bird's eye-view scanning electron microscope (SEM) image shows that uniform hexagonal pyramid structures are well arranged. We showed that the pyramid structures have high crystal quality and the thickness of InGaN is varied along the height of pyramids via transmission electron microscope. Because the InGaN/GaN double hetero-structure was grown on the nano-pyramid GaN and on the planar GaN, simultaneously, we investigated the comparative study of the optical properties. Photoluminescence (PL) spectra of nano-pyramid sample and planar sample measured at 10 K. Although the growth condition were exactly the same for two samples, the nano-pyramid sample have much lower energy emission centered at 615 nm, compared to 438 nm for planar sample. Moreover, nano-pyramid sample shows broad-band spectrum, which is originate from structural properties of nano-pyramid structure. To study thermal activation energy and potential fluctuation, we measured PL with changing temperature from 10 K to 300 K. We also measured PL with changing the excitation power from 48 ${\mu}W$ to 48 mW. We can discriminate the origin of the broad-band spectra from the defect-related yellow luminescence of GaN by carrying out PL excitation experiments. The nano-pyramid structure provided highly efficient broad-band red-color emission for the future applications of phosphor-free white LEDs.

• Radiation Oncology Journal
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• v.10 no.2
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• pp.171-180
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• 1992

The precise role of radiotherapy for low grade gliomas including the optimal radiation dose and timing of treatment remains unclear. The information given by a retrosepctive analysis may be useful in the design of prospective randomized studies looking at radiation dose and time of surgical and radiotherapeutic treatment. The records of 56 patients (M:F = 29:27) with histologically verified cerebral low grade gliomas (47 cases of grade 1 or 2 astrocytomas and 9 oligodendrogliomas) diagnosed between 1979 and 1989 were retrospectively reviewed. The extent of surgical tumor removal was gross total or radical subtotal in 38 patients ($68\%$) and partial or biopsy only in the remaining 18 patients ($32\%$). Postooperative radiation therapy was given to 36 patients ($64\%$) of the total 56 patients with minimum dose of 5000 cGy (range=1250 to 7220 cGy). The 5-and 10-year survival rates for the total 56 patients were $44\%$ and $32\%$ respectively with a median survival of 4.1 years. According to the histologic grade the 5- and 10-year survivals were $52\%$ and $35\%$ for the 24 patients respectively with grade I astrocytomas compared to $20\%$ and $10\%$ for the 23 patients with grade II astrocytomas. Survival of oligodendroglioma patients was greater than those with astrocytoma ($65\%$ vs $36\%$ at 5 years), and the difference was also remarkable in the long term period of follow up ($54\%$ vs $23\%$ at 10 years). Those who received high-dose radiation therapy ($\geq$5400 cGy) had significant better survival than those who received low-dose radiation (< 5400cGy) or surgery alone (p<0.05). The 5- and 10-year survival rates were, respectively $59\%$ and $46\%$ for the 23 patients receiving high-dose radiation, $36\%$ and $24\%$ for the 13 patients receiving low-dose radiation, and $35\%$ and $26\%$ for the 20 patients with surgery alone. Survival rates by the extent of surgical resection were similar at 5 years ($46\%$ vs $41\%$), but long term survival was quite different (p<0.01) between total/subtotal resection and partial resection/biopsy ($41\%$ and $12\%$, resepctively). Previously published studies have identified important prognostic factors in these tumor: age, extent of surgery, grade, performance status, and duration of symptoms. But in our cases statistical analysis revealed that grade I histology (p<0.025) and young age (p<0.001) were the most significant good prognostic variables.

• Korean Journal of Soil Science and Fertilizer
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• v.44 no.2
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• pp.285-292
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• 2011

In order to develop livestock wastewater treatment technology by natural purification method, the optimum filter media in small-scale livestock wastewater treatment apparatus for treating livestock wastewater were studied. Removal rates of pollutants under different filter media were in the other of coarse sand ${\fallingdotseq}$ broken stone > zeolite > calcite for COD, zeolite >> broken stone ${\fallingdotseq}$ coarse sand ${\fallingdotseq}$ calcite for T-N, and calcite > coarse sand ${\fallingdotseq}$ broken stone ${\fallingdotseq}$ zeolite for T-P. Based on the above results, the optimum filter media was coarse sand in small-scale livestock wastewater treatment apparatus. To meet acceptable effluent quality standard for livestock wastewater and to improve T-N and T-P removal efficiencies, removal efficiencies of pollutants in small-scale livestock wastewater treatment apparatus with mixed filter media were studied. The removal rates of COD, SS, T-N and T-P in effluent were 84, 94, 65 and 98% in small-scale livestock wastewater treatment apparatus with mixed filter media, respectively. For increasing the T-N and T-P removals in small-scale livestock wastewater treatment apparatus, the mixed filter media are recommended.

• Nuclear Medicine and Molecular Imaging
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• v.43 no.6
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• pp.513-518
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• 2009

Purpose: Integration of the functional information of myocardial perfusion SPECT (MPS) and the morphoanatomical information of coronary CT angiography (CTA) may provide useful additional diagnostic information of the spatial relationship between perfusion defects and coronary stenosis. We studied to know the added value of three dimensional cardiac SPECT/CTA fusion imaging (fusion image) by comparing between fusion image and MPS. Materials and Methods: Forty-eight patients (M:F=26:22, Age: $63.3{\pm}10.4$ years) with a reversible perfusion defect on MPS (adenosine stress/rest SPECT with Tc-99m sestamibi or tetrofosmin) and CTA were included. Fusion images were molded and compared with the findings from the MPS. Invasive coronary angiography served as a reference standard for fusion image and MPS. Results: Total 144 coronary arteries in 48 patients were analyzed; Fusion image yielded the sensitivity, specificity, negative and positive predictive value for the detection of hemodynamically significant stenosis per coronary artery 82.5%, 79.3%, 76.7% and 84.6%, respectively. Respective values for the MPS were 68.8%, 70.7%, 62.1% and 76.4%. And fusion image also could detect more multi-vessel disease. Conclusion: Fused three dimensional volume-rendered SPECT/CTA imaging provides intuitive convincing information about hemodynamic relevant lesion and could improved diagnostic accuracy.

• Journal of Gifted/Talented Education
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• v.24 no.6
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• pp.1001-1024
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• 2014

The purpose of the study is to explore the experiences and meaning of the AP (Advanced Placement) at the specialized school for the highly gifted through the in-depth interview with 39 college students who had graduated from the specialized schools with the AP experiences. It is expected that the AP will be expanded to the students at the Science High Schools from the year of 2015, however, there has been no study to examine the realities of the AP in-depth especially through the voices of the AP participants. Students have taken 8 required and/or selective courses as AP in average. Students usually start to take AP from the second year of the specialized school for the highly gifted, but some start from the first year through the placement test. Numbers of available AP courses vary by subjects, but relatively more courses open in the areas of math and physics. Students' opinions regarding the AP were quite positive. Specifically, the high quality of the AP class and energetic interaction between student and teacher compared to the college classes were preferred by the students. However, it was controversial whether C+ is enough for the pass condition of the AP. Students were using the shortened time by AP in diverse ways, such as early graduation, double majors, exchange students, individual researches, and so on. Most of all, they tried to search for their career interests through the AP experiences. In closing, the present study provides some advices and future directions for the better AP management, including the improvement of administrative system between schools for the gifted and the universities, and the expansion of the number of university which approves the AP system.

• Journal of the Korean Arthroscopy Society
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• v.13 no.3
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• pp.242-248
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• 2009

Purpose: To evaluate the clinical and radiologic results of the arthroscopic rotator cuff repair for partial articular surface tendon avulsion lesion. Materials and Methods: Twelve patients with symptomatic, partial articular surface tendon avulsion underwent arthroscopic rotator cuff repair between Mar. 2006 and Sep. 2008. The mean follow-up period was 18.3 months(12~36 months), and the mean age at the time of surgery was 46.9-year-old(19~64 years). Three cases had underwent rotator cuff repair after conversion to full-thickness tear and nine cases had transtendon repair with preserving bursal side cuff. Results: The mean VAS during motion was 6.2 before treatment and 2.0 at final follow-up (p<0.001). The passive forward flexion improved from $163.3^{\circ}$ preoperatively to $169.8^{\circ}$ postoperatively (p=0.038). The mean UCLA score improved from 18.4 preoperatively to 30.1 with 2 excellent, 8 good and 2 fair results at final follow-up. The mean KSS improved from 61.8 preoperatively to 76.8 at final follow-up. By examining the postoperative MR images of 5 patients, complete healing was observed in all of them. Conclusion: Arthroscopic rotator cuff repair may be an effective procedure for partial articular surface tendon avulsion in pain relief and improvement of the range of motion. If the remaining bursal side cuff fibers are intact, transtendon repair procedure with preserving the intact bursal layer of the tendon can be considered. If the remaining bursal side cuff fibers are friable or little, completion from partial-thickness to full-thickness tears with subsequent cuff repair can be considered.

• Asia Marketing Journal
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• v.11 no.3
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• pp.185-203
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• 2009

Yuhan Kimberly, a joint-venture company of Korean Yuhan Company and American Kimberly-Clark, opened a premium diaper market in Korea by launching Pull-Ups which was pants-typed diapers in 1993. Pull-Ups was imported as finished goods from Kimberly-Clark. However, in spite of its huge market share in United States, it failed to land down in Korean market because of wrong positioning strategy which did not consider domestic customers' tastes. In 1996, Yuhan-Kimberly brought out a pants-typed diaper, Huggies-Toddler, to Korean market again. This paved the way for the combination of Kimberly-Clark's production power and Yuhan-Kimberly's marketing power and led to launch new product superior to Pull-Ups. However, this product was unsuccessful in the market because of wrong positioning which did not catch domestic customer's life styles such as cultural, environmental and habitual differences in toilet training, the cost increase coming from IMF crisis in Korea, weak trust within the company, weak trust within the company, and too much higher price than regular diapers. In 2005, Yuhan-Kimberly redeveloped new pants market business strategy. It was organically combined with winning product development plan, winning communication strategy and the market structure change through the pants market creation. Customer's habit, usage and attitude were studied with total 55 times market investigations. Also, all processes from planning to designing were executed in the customer's view by investigating product research, positioning research and advertisement research. Yuhan-Kimberly repositioned new product as a wearing diaper not as a toilet training diaper and launched Huggies Magic Panty as a premium product which had 25% higher price than previous Huggies. Huggies Magic Panty was recognized as a great hit product in domestic diaper market and the sales recorded 37.6 bill won in 2006, 57.2 bill won in 2007, and 90 bill won in 2008 since launching in 2005. The reason of Huggies Magic Panty's success was the repositioning strategy deduced from the precise check of customer's usage habit. It was the winning strategy of Huggies that were market investigation in order to survive in domestic baby goods market where a lot of companies struggled intensively, the exact positioning based on its market investigation and aggressive 360 degree communication strategy to give customers impressions efficiently.

• Dementia and Neurocognitive Disorders
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• v.23 no.1
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• pp.54-66
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• 2024

Background and Purpose: Dementia subtypes, including Alzheimer's dementia (AD), dementia with Lewy bodies (DLB), and frontotemporal dementia (FTD), pose diagnostic challenges. This review examines the effectiveness of ¹⁸F-Fluorodeoxyglucose Positron Emission Tomography (¹⁸F-FDG PET) in differentiating these subtypes for precise treatment and management. Methods: A systematic review following Preferred Reporting Items for Systematic reviews and Meta-Analyses guidelines was conducted using databases like PubMed and Embase to identify studies on the diagnostic utility of ¹⁸F-FDG PET in dementia. The search included studies up to November 16, 2022, focusing on peer-reviewed journals and applying the goldstandard clinical diagnosis for dementia subtypes. Results: From 12,815 articles, 14 were selected for final analysis. For AD versus FTD, the sensitivity was 0.96 (95% confidence interval [CI], 0.88-0.98) and specificity was 0.84 (95% CI, 0.70-0.92). In the case of AD versus DLB, ¹⁸F-FDG PET showed a sensitivity of 0.93 (95% CI 0.88-0.98) and specificity of 0.92 (95% CI, 0.70-0.92). Lastly, when differentiating AD from non-AD dementias, the sensitivity was 0.86 (95% CI, 0.80-0.91) and the specificity was 0.88 (95% CI, 0.80-0.91). The studies mostly used case-control designs with visual and quantitative assessments. Conclusions: ¹⁸F-FDG PET exhibits high sensitivity and specificity in differentiating dementia subtypes, particularly AD, FTD, and DLB. This method, while not a standalone diagnostic tool, significantly enhances diagnostic accuracy in uncertain cases, complementing clinical assessments and structural imaging.

• Journal of Acupuncture Research
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• v.25 no.5
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• pp.151-165
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• 2008

Objectives : To evaluate the effects of Head Acupuncture versus Upper and Lower Limbs Acupuncture on signal activation of Blood Oxygen Level Dependent(BOLD) fMRI on the Brain and Somatosensory Cortex. Subjects and Methods : 10 healthy normal right-handed female volunteer were recruited. The average age of the 10 subjects was 30 years old. The BOLD functional MRI(fMRI) signal characteristics were determined during tactile stimulation was conducted by rubbing 4 acu-points in the right upper and lower limbs($LI_1$, $LI_{10}$, $LV_3$, $ST_{36}$). After stimulation of Head Acupuncture in Sishencong($HN_1$), $GB_{18}$, $GB_9$, $TH_{20}$ of Left versus Upper and Lower Limbs Acupuncture($LI_1$, $LI_{10}$, $LV_3$, $ST_{36}$ of Right) and took off needles. Then the BOLD fMRI signal characteristics were determined at the same manner. Results : 1. When touched with cotton buds(sensory stimulation), left Parietal Lobe, Post-central Gyrus, primary somatosensory cortex(BA 1, 2, 3), and primary motor cortex(BA 4) were mainly activated. When $ST_{36}$ was stimulated, Frontal Lobe, Parietal Lobe, Cerebellum, and Posterior Lobe as well as Inter-Hemispheric displaying a variety of regions. 2. In signal activation before and after Head Acupuncture reaction, it showed signal activation after removing the acupuncture needle and right Somatosensory Association Cortex, Postcentral Gyrus, and Parietal Lobe were more activated. 3. In reactions of before and after Upper and Lower Limb Acupuncture, it also showed signal activation after removing the acupuncture needle and bilateral Occipital Lobe, Lingual Gyrus, visual association cortex, and Cerebellum were activated. 4. After acupuncture stimulation, In Upper and Lower Limb Acupuncture Group, left frontal Lobe, Precentral Gyrus and Bilateral parietal lobe, Postcentral Gyrus and Primary Somatosensory Cortex(BA 2) were activated. In Head Acupuncture Group, which has most similar activation regions, but especially right Pre-Post central Gyrus, Primary Somatosensory Cortex(BA 3), Primary Motor Cortex, frontal Lobe and Parietal Lobe were activated. Conclusions : When sensory stimulation was done with cotton buds on four acup-points($LI_1$, $LI_{10}4, $LV_3$, $ST_{36}$), while bilaterally activated, contralateral sense was more dominant. It showed consistency with cerebral cortex function. When $ST_{36}$ was stimulated Frontal Lobe, Parietal Lobe, Cerebellum, Posterior Lobe as well as Inter-Hemispheric were stimulated. In Head Acupuncture, it showed more contralateral activation after acupuncture. In Upper and Lower Limb Acupuncture, it showed typically contralateral activation and deactivation of limbic system after acupuncture stimulation. Therefore, there were different fMRI BOLD signal activation reaction before and after Head Acupuncture vs Upper and Lower Limb Acupuncture which might be thought to be caused by acu-points' sensitivity and different sensory receptor to response acupuncture stimulation.

• Korean Chemical Engineering Research
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• v.56 no.6
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• pp.871-877
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• 2018

Storing the surplus energy from renewable energy resource is one of the challenges related to intermittent and fluctuating nature of renewable energy electricity production. $CO_2$ methanation is well known reaction that as a renewable energy storage system. $CO_2$ methanation requires a catalyst to be active at relatively low temperatures ($250-500^{\circ}C$) and selectivity towards methane. In this study, the catalytic performance test was conducted using a pressurized bubbling fluidized bed reactor (Diameter: 0.025 m and Height: 0.35 m) with $Ni/{\gamma}-Al_2O_3$ (Ni70%, and ${\gamma}-Al_2O_3$30%) catalyst. The range of the reaction conditions were $H_2/CO_2$ mole ratio range of 4.0-6.0, temperature of $300-420^{\circ}C$, pressure of 1-9 bar, and gas velocity ($U_0/U_{mf}$) of 1-5. As the $H_2/CO_2$ mole ratio, temperature and pressure increased, $CO_2$ conversion increases at the experimental temperature range. However, $CO_2$ conversion decreases with increasing gas velocity due to poor mixing characteristics in the fluidized bed. The maximum $CO_2$ conversion of 99.6% was obtained with the operating condition as follows; $H_2/CO_2$ ratio of 5, temperature of $400^{\circ}C$, pressure of 9 bar, and $U_0/U_{mf}$ of 1.4-3.