• Proceedings of the KIPE Conference
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• 2001.10a
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• pp.502-507
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• 2001

This paper proposes a novel detection algorithm of faulted voltages under the unbalanced condition. To quantify the standard of unbalance under the faulted conditions, the 3-phase unbalanced voltages are decomposed into two balanced 3-phase symmetrical components of the positive and negative sequence voltages, which is defined by the magnitude factor (MF) and unbalance factor (MF). It is analyzed that MF and UF values are given as the dc constant values even though unbalance condition. This paper also proposes the control scheme of the instantaneous voltage sag corrector based on this detection algorithm. The validity of the proposed algorithm is verified through the EMTDC simulation and experiments.

• Proceedings of the Korean Information Science Society Conference
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• 2006.10d
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• pp.502-505
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• 2006

본 논문은 고해상도의 영상을 처리하는 이동기기 등에 사용되는 SoC(System On a Chip)에 구현이 용이한 효과적인 화질 향상 (잡음감소와 윤곽강조) 을 위한 방법과 구조에 대한 것이다. 최근 이동기기의 발전과 진화에 따라 여러 형태의 이동기기가 개발되고 있는데 그 중 최근 인기를 끌고 있는 포터블 미디어 플레이어 (PMP)나 HD(Hight Definition)급 camcorder 등이 고해상도의 영상을 처리하는 이동기기로 분류될 수 있다. 이러한 이동기기에서 고해상도 영상에 대한 화질 향상을 기존의 복잡한 방법을 사용해 처리한다면 메모리 대역폭이나 하드웨어 크기 등의 증가로 이동기기에서 구현하는데 어려움이 따른다. 이에 본 논문에서는 이러한 이동기기에서의 고해상도의 화질 향상을 입력영상의 종류에 따라 선택적으로 메모리 대역폭 사용 없이 하드웨어 크기를 최소화하여 FPGA (field programmable gate array)나 ASIC (application specific integrated circuit)으로 구현이 용이하도록 하는 방법과 구조에 대해 설명하고 실제 영상을 가지고 실험한 결과로 주관적 화질 향상 효과를 가져 온 것을 확인할 수 있었다.

• Structural Engineering and Mechanics
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• v.33 no.4
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• pp.485-502
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• 2009

A new 8-node serendipity quadrilateral plate bending element (MQP8) based on the Mindlin-Reissner theory for the analysis of thin and moderately thick plate bending problems using Integrated Force Method is presented in this paper. The performance of this new element (MQP8) is studied for accuracy and convergence by analyzing many standard benchmark plate bending problems. This new element MQP8 performs excellent in both thin and moderately thick plate bending situations. And also this element is free from spurious/zero energy modes and free from shear locking problem.

• Journal of the Korea Institute of Military Science and Technology
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• v.13 no.3
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• pp.493-502
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• 2010

In this paper, the ionization characteristics of noble gases are studied numerically behind strong shock waves. As a first step, the equilibrium ionization mechanism of noble gases is modeled in wide ranges of temperature and pressure. As a next step the equilibrium ionization model is coupled with fluid dynamic equations to analyze the local thermodynamic equilibrium(LTE) ionization process at high temperature and pressure conditions behind the strong imploding shock waves. The ionization characteristics of xenon gas is studied in a wide range of test conditions with thermal radiation effects. Hence, the results give optimal conditions of maximum ionization and radiation behind the imploding shock waves.

• Journal of Magnetics
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• v.21 no.4
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• pp.496-502
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• 2016

Doped and undoped barium hexaferrite powders ($BaFe_{12}O_{19}$, $Ba_{0.7}Ti_{0.3}Fe_{12}O_{19}$ and $Ba_{0.7}La_{0.3}Fe_{12}O_{19}$) were produced by the sol-gel method. The effects of substituting elements were studied in terms of the magnetic properties of barium hexaferrite powders. The magnetic properties were remarkably changed by the substitution of $La^{3+}$ and $Ti^{4+}$ ions for the $Ba^{2+}$ ion and were accompanied by oxygen deficiency in the $BaFe_{12}O_{19}$. Coercivities ($H_C$) from 4200 to 5100 Oe, remanences ($M_R$) from 22 to 49 emu/g and saturation magnetizations ($M_S$) from 41 to 73 emu/g were obtained for different samples. The obtained results were discussed in detail.

• Investigative Magnetic Resonance Imaging
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• v.5 no.2
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• pp.130-137
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• 2001

Purpose : Our purpose was to compare maximum relative cerebral blood volume (rCBV) with histologic grade of cerebral gliomas. Materials and methods : First-pass perfusion MR imaging was performed preoperatively in 16 patients with pathologically proven cerebral gliomas (7 glioblastoma, 2 anaplastic astrocytoma, 1 anaplastic oligodendroglioma, 5 low-grade astrocytoma, and 1 low-grade oligodendroglioma). Maximum rCBV was compared with histologic diagnosis and grade of the tumor. Results : Maximum rCBVs of glioblastomas were in the range of 433% to-1330% (average, 790 %), as compared with those of contra-lateral normal white matters. Maximum rCBVs of two non-enhancing anaplastic astrocytomas were 66% and 284%, respectively. Maximum rCBV of one well-enhancing anaplastic oligodendroglioma was 702%. Maximum rCBVs of low-grade astrocytomas were in the range of 80%-369% (average, 202%). Maximum rCBV of one low-grade oligodendroglioma was 1450%, even higher than those of glioblastomas. Conclusion : Maximum rCBV was higher in glioblastoma than in low-grade astrocytoma without overlapping. However, there was no difference of maximum rCBV between non-enhancing anaplastic astrocytoma and low-grade astrocrtoma.

• Journal of The Korean Society of Integrative Medicine
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• v.8 no.3
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• pp.11-20
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• 2020

Purpose : The purpose of this study was to determine the correlation between smartphone use, body composition, posture and muscle properties of elementary school students. Methods : A total of 22 healthy elementary school students in Daejeon, South Korea, participated in this study with informed consent. Smartphone use was evaluated with Smartphone addiction self-report scale (S-scale) for youth. Body composition (BMI, percent body fat, body fat mass, and skeletal muscle mass) was measured using Inbody. To assess posture, forward head posture and round shoulder posture were measured using Dartfish motion analysis. Muscle properties (muscle tone, stiffness, and elasticity) were measured on the upper trapezius, splenius capitis and sternocleidomastoid muscles using Myoton. To investigate the correlation between the main variables, Pearson correlation analysis was performed. Results : Disturbance of adaptive function, which is one of sub-component of S-scale, had a weak positive correlations with BMI (r=.538, p<.01), and body fat mass (r=.453, p<.05). However, scores of S-scale showed no correlation with posture and muscle properties. The correlation between posture and muscle properties was analyzed, and round shoulder posture revealed a weak positive correlation with respect to stiffness (r=.418, p<.05) and elasticity (r=.502, p<.05) of the sternocleidomastoid muscle. Conclusion : Scores of S-scale demonstrated a weak correlation with body composition (BMI) among elementary school students, whereas S-scale scores were not correlated with the posture and muscle properties. Further research is needed to identify and focus on potential high-risk user groups of elementary students who are more dependent upon smartphones.

• Tuberculosis and Respiratory Diseases
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• v.86 no.4
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• pp.272-283
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• 2023

Background: In patients with chronic obstructive pulmonary disease (COPD), decreased muscle mass is a frequently encountered comorbidity in clinical practice. However, the evaluation of muscle mass in patients with COPD in real-world practice is rare. Methods: We retrospectively reviewed the electronic medical records of all patients with COPD who underwent bioelectrical impedance analysis at least once between January 2011 and December 2021 in three hospitals. Then, we analyzed the performance rate of muscle mass measurement in the patients and the correlation between muscle mass, clinical parameters, and COPD prognosis. Results: Among the 24,502 patients with COPD, only 270 (1.1%) underwent muscle mass measurements. The total skeletal muscle mass index was significantly correlated with albumin, alanine transaminase, and creatinine to cystatin C ratio in patients with COPD (r=0.1614, p=0.011; r=0.2112, p=0.001; and r=0.3671, p=0.001, respectively). Acute exacerbation of COPD (AE COPD) was significantly correlated with muscle mass, especially the truncal skeletal muscle mass index (TSMI) in males (r=-0.196, p=0.007). In the multivariate analysis, TSMI and cystatin C were significant risk factors for AE COPD (hazard ratio, 0.200 [95% confidence interval, CI, 0.048 to 0.838] and 4.990 [95% CI, 1.070 to 23.278], respectively). Conclusion: Low muscle mass negatively affects the clinical outcomes in patients with COPD. Despite its clinical significance, muscle mass measurement is performed in a small proportion of patients with COPD. Therefore, protocols and guidelines for the screening of sarcopenia in patients with COPD should be established.

• Korean journal of applied entomology
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• v.48 no.2
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• pp.165-170
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• 2009

This study was conducted to investigate specific stages and distribution of overwintering nymphs of green rice leafhopper, Nephotettix cincticeps by measuring head capsule width. The nymphal head capsule width of the 1st instar to the 5th instar was 0.381, 0.502, 0.673, 0.979 and 1.128 mm, respectively. lts coefficient variation was 5.3, 4.0, 3.0, 4.5 and 5.3%, respectively. Growth ratio of each instar was not significantly different among 2nd to 4th instars as 1.31 to 1.34, but for the 5th instar it decreased as 1.28. The logarithm of the nymphal head capsule width was regressed as a function of the stage number of insects, resulting in LogY = 1.4627 + 0.1192X ($r^2= 0.9993$). Also fitness to the Dyar's law for the nymphal head capsule width of each instar was 98% or over and the Dyar's constant (K) was 1.316. The occurrence of N. cincticeps was maximum at the end of January with 195 individuals/0.25 $m^2$. The most abundant instar in the overwintering N. cincticeps population was 4th instar accounting for over 90%. Population of the 5th instar began to increase from mid-March, and adults began to occur in early April.

• Food Science and Preservation
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• v.20 no.4
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• pp.502-509
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• 2013

This study was conducted in order to monitor the extraction conditions for a gel-state beverage development of the Opuntia ficus-indica stem. Moreover, the organoleptic properties of the beverage prepared by the extract were optimized using the response surface methodology (RSM). The determination coefficient ($R^2$) value for the extraction yield of the stem was 0.95 (p<0.01). The maximum extraction yield was obtained at an extraction temperature of $93.02^{\circ}C$, 123 min of extraction time and 22.57 mL/g of water to sample. The beverage was prepared with the addition of xanthan gum, sugar and persimmon vinegar to the extract with a central composite design. The maximum organoleptic color of the beverage was obtained at 0.38% xanthan gum, 7.91% sugar and 0.76% persimmon vinegar. The maximum organoleptic flavor was obtained at 0.30% xanthan gum, 7.06% sugar and 1.26% persimmon vinegar. The maximum organoleptic taste was obtained at 0.22% xanthan gum, 10.36% sugar and 0.90% persimmon vinegar. The maximum overall palatability (3.92 score) of the gel-state beverage was obtained at 0.35% xanthan gum, 10.83% sugar and 1.21% persimmon vinegar.