• Proceedings of the ESK Conference
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• 1997.04a
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• pp.304-310
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• 1997

연세대학교 영동세브란스 병원에서 94년 요통환자 2천4백10명을 직업별로 분류한 결과, 주부가 56%, 학생이 13.4%를 차지했다고 발표했다. 특히 주부환자비율은 85-90년에 38.9%로 조사된 것에 비하면 주목할만한 증가세를 보였다. 이러한 주부요통증가의 원인 중 임상적으로 이미 확인된 것이 하이힐에 의한 것이다. 하이힐을 신을 경우 허리에 부담을 주고 요통을 유발할 수 있다는 것이다. 그러나, 이러한 임상적 가설에 대한 구체적인 연구나 검증이 이루어진 바 없어 하이힐이 허리에 어떤 영향을 주는지에 대해 확인할 수 없었다. 따라서, 본 연구에서는 하이힐이 허리에 미치는 영향에 대한 임상적 가설을 검증하고 영향 정도에 대한 구체적 수치를 제시하고자 한다. 이를 위해 5명의 신체 건강한 20대 초반의 여성들이 모집되었고, 하이힐의 굽높이를 독립변수로, 허리 근육 피로도를 종속 변수로 설정하여 하이힐의 굽높이가 허리 근육에 미치는 영향에 대해 조사하였다. 허리 근육 피로도는 Spectral EMG를 통해 분석하였고 정량화되었다. 측정된 자료를 통계 분석한 결과, 하이힐의 굽높이가 여성의 허리 근육에 유의하게 영향을 미침이 발견되었고, 우리 나라 여성에게 적합한 하이힐의 굽높이는 3-5cm 정도임이 밝혀졌다. 본 연구 결과는 하이힐의 디자인에 있어서 굽높이에 대한 추천치로 제안될 수 있으며 여성들의 하이힐로 인한 요통을 어느 정도 예방할 수 있어 여성 근로 손실을 줄이는 데 기여할 수 있다. 본 연구를 하이힐 굽형태나 충격흡수 등의 독립변수 요인을 추가하여 확대하면 하이힐 디자인에 응용하는데 더욱 유용하리라 생각된다. 없었다. 전신쾌적감은 약간 쾌적하게 나타났고 전신온냉감은 약간 따뜻하다라고 나타났으며 손가락끝의 동통감은 약간 아프다고쪽으로 나타났다.때문에 이를 디자인에 곧바로 적용시키기 어려운 점이 있다. 이에 본 연구는 기존의 바용성 평가를 위한 분석도구들이 갖는 문제 점들 해결하여 제품의 사용자 인터페이스 디자인 개발과정에서 활용할 수 있는 평가 분석도구를 개발하는 것을 목표로 한다. 이를 위해 첫째, 다양한 유형의 정보를 포함하는 비디오 정보를 선정하였따. 둘째, 데이터를 다양한 측면에서 추출할 수 있는 Data logger를 개발하였다. 셋째, 데이터를 시각적으로 정리하고 분석할 수 있는 도구를 제안한다. 마지막으로 인터페이스 디자인에서 여러 가지 디자인안을 도출해 내는 작업에 이용할 수 있는 종합화과정을 개발한다. 이러한 일련의 과정이 통합된 컴퓨터 시스템 안에서 이루어지도록 프로그램을 개발하여 정보의 유용성을 높일 수 있도록 한다.at the entropy index as a measurement of inter-business relatedness is not significant but technological relatedness index is significant. OLS estimates on pooled data were considerably different from FEM or REM estimates on panel data. By introducing interaction effect among the three variables for business portfolio properties, we obtai

• Journal of the Korean Magnetics Society
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• v.4 no.2
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• pp.122-125
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• 1994

The magnetic properties of Nd-Fe-B alloys of containing 4 at.% Nd have been studied for the development of new type rare-earth magnets. The amorphous phase of a melt-spun $Nd_{4}Fe_{85.5}B_{10.5}$ alloy is transformed into the phases which have a small amount of $Nd_{2}Fe_{14}B_{1}$ in ${\alpha}-Fe$ matrix by annealing above their crystallization temperature. The addition of Mo, Nb, V or Cu to $Nd_{4}Fe_{85.5}B_{10.5}$ alloy results in the reduction of grain size and the sub¬sequent improvement of the coercivity. The coercivity of $Nd_{4}Fe_{82}B_{10}M_{3}Cu_{1}$(M = Mo, Nb, V) alloys increases in the order of M = V < Nb < Mo and shows the highest value of 2.7 kOe when M = Mo. On the other hand, the rem¬anence of these alloys shows the opposite trend and the rn>st improved value of 1.35 T is observed when M = V.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.27 no.7
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• pp.599-611
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• 2016

This paper proposes a cognitive engine platform that enables dynamic spectrum access(DSA) based on a spectrum sharing system for the military tactical network environment. The current military tactical wireless communication system is increasing need to secure a supplementary wireless spectrum to ensure that multiple wireless networks for different weapon systems co-exist, so that tactical wireless communication between the same or different systems can be operated effectively. This paper examined policy development and research activities engaged by the U.S. and European countries on wireless spectrum sharing to secure more spectrum. It also introduces the current status of cognitive engine development, which is the core technology of tactical wireless communication for DSA. In addition, based on the investigation performed into the latest trends, we propose a platform structure for a cognitive engine based on a spectrum sharing method where more frequencies can be added for tactical radio communication, so that DSA can be realized, and wireless networks of different weapon systems can co-exist.

• Journal of Korean Society of Water and Wastewater
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• v.14 no.1
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• pp.62-75
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• 2000

Most of biological treatment to remove contaminants in municipal wastewater have been conducted by activated sludge process. But, the process have several probIems such as enormous site needed for construction of treatment facilities, unstable treatment due to limited ability to control load fluctuation, frequent sludge bulking and appearance of lots of surplus sludge. In this study, the experiments were performed through submerging biofilm of PEPP media in existing aeration tank with raw water from municipal wastewater treatment plant and then submerging PVDC and PEPP media, different from shape and chemical peculiarity in anoxic reactor. Throughout the experience, nutrient removal efficiency according to HRT, nitrogen phosphorous removal efficiency, behavior of nitrogen and dewatering efficiency have been compared and analysed with those of activated sludge process. As the results, BOD removal efficiency according to BOD volumetric load and F/M ratio was not found any differency in two processes, but was decreased below 90% as going along the condition of high load in activated sludge process. Kinetic coefficient was $K_{max}=1.162day^{-1}$, $K_s=53.77mg/L$, $Y=0.166mgVSS/mgBOD_{rem}$. and $K_d=0.019day^{-1}$. It was found that the removal efficiency, even though in aerobic condition, in biofilm process equipped anoxic reactor was higher than the one in activated sludge process within the range of 70~80%, and became better as HRT increased. Phosphorous removal efficiency was not found any differency in two processes. In biofilm process, treament efficiency even in conditions of high load was not decreased, because the biomass concentration could be maintained in high condition compared with activated sludge process. As HRT increased, suspended and attached biomass was increased and the other hand, F/M ratio was decreased as biomass' increasing. Biomass thickness was increased. from $10.43{\mu}m$ to $10.55{\mu}m$ as HRT increased and density of biomass within $40.79{\sim}41.16mg/cm^2$. The results also present that the dewatering efficiency of sludge generated in biofilm process was higher than in activated sludge process, and became better as HRT increased.

• Sleep Medicine and Psychophysiology
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• v.3 no.2
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• pp.65-76
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• 1996

Natural sleep pattern and its physiology in childhood are much different from those in adulthood. Several aspects of clinical evaluation for sleepiness in childhood are more difficult than in adulthood. These difficulties are due to several factors. First, excessive sleepiness in childhood do not always develop functional impairments. Second, objective test such as MSLT may not be reliable since it is hard to be certain that the child understand instructions. Third, sleepiness in children is often obscured by irritability. paradoxical hyperactivity, or behavioral disturbances. Anseguently, careful clinical evaluation is needed for the sleepy children. Usual causes of sleepiness in children are the disorders that induce insufficient sleep such as sleep apnea syndrome, schedule disorder, underlying medical and psychiatric disorder, and so forth. After excluding such factors, we can diagnose the hypersomnic disorders such as narcolepsy, Kleine-Levin syndrome, and idiopathic central nervous system hypersomnia. Among the variety of those causes of sleepiness, I reviewed the clinical difference of narcolepsy and obstructive sleep apnea syndrome in childhood compared with in adulthood. Recognition of the childhood narcolepsy is difficult because even severely sleepy children often do not develop pathognomic cataplexy and associated REM phenomena until much later. Since childhood narcolepsy give srise to many psychological, academical problem. Practicers should be concerned about these aspects. Childhood obstructive sleep apnea syndrome is different from adult obstructive sleep apnea syndrome too. Several aspects such as pathophysiology. clinical feature, diagnostic criteria, complication, management, and prognosis differ from those in the adult syndrome. An important feature of childhood obstructive sleep apnea syndrome is the variety of severe complications such as behavioral disorders, cognitive impairment, cardiovascular symptoms, developmental delay, and ever death. Fortunately, surgical interventions like adenotosillectomy or UPPP are more effective for Childhood OSA than adult form. CPAP is a "safe, effective, and well-tolerated" treatment modality too. So if early detection and proper management of childhood OSA were done, the severe complication would be prevented or ever cured.

• Sleep Medicine and Psychophysiology
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• v.1 no.2
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• pp.172-181
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• 1994

Obstructive sleep apnea syndrome(OSAS) is most frequently diagnosed in the sleep laboratories and its severity is objectively estimated. In terms of treatment, the most prevalent method is the continuous positive airway pressure(CPAP) application as of now. However, in Korea, CPAP is still not sufficiently known and it is attributable to the fact that sleep study facilities have not been popularized. In this article, the authors present their own experience with CPAP in nine subjects with OSAS. In this study, CPAP was found to decrease stage 1 sleep and to increase stage 2 sleep, with increasing mean oxygen saturation and decreasing lowest oxygen saturation during nocturnal sleep. Also, it tended to increase sleep continuity and generally to improve sleep architecture. Rebound slow wave and/or REM sleep stages during CPAP were also noted in 8 out of 9 cases. The authors suggest that CPAP should be considered as the primary mode of treatment for patients with obstructive sleep apnea syndrome and related educational programs for physicians should be developed and provided by sleep specialists.

• The Journal of Asian Finance, Economics and Business
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• v.7 no.9
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• pp.409-418
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• 2020

The human and capital resources from foreign investors are important sources of finance for developing countries. Foreign ownership can help the firm to raise funds for operations and the foreign management can help the firm expand the market and improve management. However, does this really happen to Vietnamese firm? To find the answer to that question, this paper examines the impact of foreign ownership and management on the financial performance of listed firms on Vietnam's stock market. The data collected include 427 listed firms in all fields over five years, from 2014 to 2018. The financial performance is measured by Tobin's Q, ROA and ROE. The study carried out testing of each model by the least squares method of Pool OLS, assessing random effects (REM) and evaluating fixed effects (FEM). The most effective model is the FEM model. The results show that the foreign ownership ratio and the size of the firm have a positive impact on the financial performance. The foreign management, the age of the firms, the liquidity and financial leverage have a negative impact on the financial performance. Based on the research results, the study proposes some recommendations to improve the financial performance of listed firms in Vietnam.

• Korean Journal of Materials Research
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• v.28 no.9
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• pp.489-494
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• 2018

Lead free $(1-x)(0.675BiFeO_3-0.325BaTiO_3)-xLiTaO_3$ (BFBTLT, x = 0, 0.01, 0.02, and 0.03, with 0.6 mol% $MnO_2$ and 0.4 mol% CuO) were prepared by a solid state reaction method, followed by air quenching and their crystalline phase, morphology, dielectric, ferroelectric and piezoelectric properties were explored. An X-ray diffraction study indicates that lithium (Li) and tantalum (Ta) were fully incorporated in the BFBT materials with the absence of any secondary phases. Dense ceramic samples (> 92 %) with a wide range of grain sizes from $3.70{\mu}m$ to $1.82{\mu}m$ were obtained in the selected compositions ($0{\leq}x{\leq}0.03$) of BFBTLT system. The maximum temperatures ($T_{max}$) were mostly higher than $420^{\circ}C$ in the studied composition range. The maximum values of maximum polarization ($P_{max}{\approx}31.01{\mu}C/cm^2$), remnant polarization ($P_{rem}{\approx}22.82{\mu}C/cm^2$) and static piezoelectric constant ($d_{33}{\approx}145pC/N$) were obtained at BFBT-0.01LT composition with 0.6 mol% $MnO_2$ and 0.4 mol% CuO. This study demonstrates that the high $T_{max}$ and $d_{33}$ for BFBTLT ceramics are favorable for industrial applications.

• The Proceeding of the Korean Institute of Electromagnetic Engineering and Science
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• v.6 no.3
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• pp.15-23
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• 1995

The antenna height of the mobile communications lower than its typical surroundings causes multipath fading usually resulting in fast fluctuations of both signal strength and wave length in mobile radio communications. Therefore, there have been developed and used various wave be- havior prediction models, in some other foreign countries, based on the measurement data rather than on theoretical derivation. The main purpose of this paper is to examine the wave propagation characteristics particularly in Korean terrain with the measurements made in four types of different areas - a large city area, a small city area, a flat terrain area, and a mountain area. Those areas have been classified according to the terrain characteristics with which the particular area contains, such as scale and number of buildings, highways, trees, and so on. With the measured data of the field strength in the frequency band of pager system obtained from those four different areas, we compared the calculated ones from both Hata's and TIREM prediction models which are often applied in Korea.

• Korean Journal of Pharmacognosy
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• v.45 no.3
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• pp.240-248
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• 2014

Gyejibokryeong-hwan (GJBRH) has been used for treatment of patients with climacteric syndrome. In this study, an ultra-performance liquid chromatography-electrospray ionization-mass spectrometer (UPLC-ESI-MS) method was established for the simultaneous quantification of seven marker compounds in GJBRH extract. In addition, we assessed the antioxidant effects of GJBRH. All analytes were separated by gradient elution using two mobile phases on a UPLC BEH $C_{18}$ column and maintained at $45^{\circ}C$. The antioxidant activities of GJBRH were evaluated by measuring free radical scavenging activities on 2,2'-azinobis-3-ethyl-benzothiazoline-6-sulfonic acid (ABTS) and 1-1-diphenyl-2-picrylhydrazyl (DPPH). The inhibitory effects on low-density lipoprotein (LDL) oxidation were evaluated by the formation of thiobarbituric acid relative substances (TBARS) and relative electrophoretic mobility (REM). Regression equations of the seven compounds were acquired with $r^2$ values ${\geq}0.9988$. The amounts of the seven compounds, amygdalin, albiflorin, paeoniflorin, coumarin, cinnamic acid, cinnamaldehyde, and paeonol in GJBRH water extract were 21.71, 2.16, 17.17, 1.97, 0.40, 0.78, and 3.42 mg/g, respectively. The GJBRH showed the radical scavenging activity in a dose-dependent manner. The concentration required for 50% reduction ($RC_{50}$) against ABTS and DPPH radicals were $54.18{\mu}g/mL$ and $79.53{\mu}g/mL$. Furthermore, GJBRH reduced the oxidation properties of LDL induced by $CuSO_4$.