• Bulletin of the Korean Chemical Society
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• 제25권12호
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• pp.1881-1888
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• 2004

A series of $NiO-TiO_2$/$WO_3$ catalysts was prepared by drying powdered $Ni(OH)_2-Ti(OH)_4$ with ammonium metatungstate aqueous solution, followed by calcining in air at high temperature. Characterization of prepared catalysts was performed by using FTIR, Raman, XPS, XRD, and DSC and by measuring surface area. Upon the addition of tungsten oxide to titania up to 25 wt%, the specific surface area and acidity of catalysts increased in proportion to the tungsten oxide content due to the interaction between tungsten oxide and titania. Since the -$TiO_2$/stabilizes the tungsten oxide species, for the samples equal to or less than 25 wt%, tungsten oxide was well dispersed on the surface of titania, but for the samples containing above 25 wt%, the triclinic phase of $WO_3$ was observed at calcination temperature above 400 $^{\circ}C$. The catalytic activities of 10-NiO-$TiO_2$/$WO_3$ for 2-propanol dehydration and cumene dealkylation were correlated with the acidity of catalysts measured by ammonia chemisorption method. NiO may attract reactants and enhance the local concentration of reactants near the acid sites, consequently showing the increased catalytic activities.

• Journal of the Optical Society of Korea
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• 제13권1호
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• pp.28-32
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• 2009

In order to obtain high quality images of thin objects, we performed an experiment of proton radiography by using low energy protons generated from the interaction of an ultrashort ultraintense laser with solid targets. The protons were produced from a thin polyimide target irradiated by the laser pulse, and their maximum energy was estimated at up to 1.8 MeV. A CR-39 nuclear track detector was used as a proton radiography screen. The proton images were obtained by using an optical microscope and the spatial resolution was evaluated by a Modulation Transfer Function (MTF). We have achieved about $10\;{\mu}m$ spatial resolution of images. The obtained spatial resolution shows about $4{\sim}5$ times better value than the conventional X-ray radiography for inspection or non-destructive test (NDT) purpose.

• The Journal of Advanced Prosthodontics
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• 제1권1호
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• pp.1-5
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• 2009

STATEMENT OF PROBLEM. Poor wettability of denture relining materials may lead to retention problems and patient discomfort. PURPOSE. Purpose of this study is to compare and evaluate wettability of nine denture relining materials using contact angle measurements under air and water storage over time. MATERIAL AND METHODS. Nine denture relining materials were investigated in this study. Two heat-curing polymethyl-methacrylate(PMMA) denture base materials: Vertex RS, Lang, one self-curing polyethyl-methacrylate(PEMA) chairside reline resin: Rebase II, six silicone relining materials: Mucopren soft, Mucosoft, $Mollosil^{{R}}$ plus, Sofreliner Touch, GC $Reline^{TM}$ Ultrasoft, Silagum automix comfort were used in this experiment. Contact angles were measured using high-resolution drop shape analysis system(DSA 10-MK2, KRUESS, Germany) under three conditions(in air after setting, 1 hour water storage, and 24 hours water storage). Nine materials were classified into three groups according to material composition(Group 1: PMMA, Group 2: PEMA, Group 3: Silicone). Mean values of contact angles were compared using independent samples t-test and one-way ANOVA, followed by a Scheffe's post hoc analysis($\alpha$=0.01). RESULTS. Contact angles of materials tested after air and water storage increased in the following order: Group 1(PMMA), Group 2(PEMA), Group 3(Silicone). Heat-cured acrylic denture base resins had more wettability than silicone relining materials. Lang had the highest wettability after 24 hours of water storage. Silicone relining materials had lower wettability due to their hydrophobicity. Wettability of all denture relining materials, except Rebase II and $Mollosil^{{R}}$ plus, increased after 24 hours of water storage. CONCLUSIONS. Conventional heat-cured resin showed the highest wettability, therefore, it can be suggested that heat-cured acrylic resin is material of choice for denture relining materials.

• 가정과삶의질연구
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• 제34권5호
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• pp.83-98
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• 2016

The purpose of this study was to investigate the relationship among toddler's symbolic play level, mother's responsiveness and verbal interaction. The subjects were 56 pairs of 24-29 months old toddlers and their mothers. The toddler's symbolic play level was classified using categories by Gowen(1995). The mother's verbal interaction was coded during a 10-minute-free play session with her toddler using Caldera, Huston, and O'Brien's(1989) categories. PICCOLO(The Parenting Interactions with Child Checklist of Observations Linked to Outcomes) by Roggman, Cook, Innocenti, Jump, Norman, & Christiansen(2009) was used to investigate the mother's responsiveness. While the mothers played with their toddlers during a 10-minute-free play session, their interaction were videotaped. The data were analyzed by means, t-test, and correlations. The results of the study were as follows: First, the mean levels of the toddler's symbolic play were in level 3, 'the pretending others'. Also girls spent more symbolic play time with mothers than boys. Second, mothers' responsiveness was generally high in free play with their toddlers. Mothers frequently used 'questions' 'comments' and 'fantasy statements'. Mothers with girls used more 'questions' than mothers with boys. Third, there was a significant relationship among toddler's symbolic play level, mother's responsiveness and verbal interaction. Maternal responsiveness and 'fantasy statements' were positively related with the mean level, and the frequency of play. The 'questions' and 'answers' were also related with symbolic play level and frequency. But 'praise' was negatively related with symbolic play frequency. In conclusion, this study suggested that toddler's symbolic play level was related with mother's responsiveness and verbal interaction during free play.

• 한국조경학회지
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• 제44권4호
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• pp.14-21
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• 2016

이 논문은 창경원을 근대적 도시 공원으로 보고, 창경원의 공간적 성격과 그곳에서 창출된 공원 문화의 특징을 파악하고자 했다. 먼저 창경원 성립의 배경을 파악했으며, 이를 바탕으로 세 가지 측면에서 근대 도시 공원으로서 창경원의 성격을 제시했다. 첫째, 대외적 선전과 과시의 장으로서 창경원의 성격, 특히 개원 초기 해외 사절과 고위 인사들의 방문에 주목했다. 특히 애초에 이곳을 근대적 공원으로 만들고자 계획했던 내용에 바탕을 두고, 근대 도시 공원으로서의 성격을 살펴보았다. 둘째, 계몽과 교화의 장으로서 1920년대 창경원 이용이 보다 대중화 경향을 띠기 시작했다는 점을 파악하고, 여성과 아동을 위한 행사와 새로운 시설의 등장에 주목했다. 셋째, 창경원을 공원으로 인식하고 이용했던 당대의 기록을 조사하여 그 문화적 특징을 파악했다.

• Archives of Plastic Surgery
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• 제32권5호
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• pp.619-624
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• 2005

Patency of the radial artery plays an important role in the survival of radial forearm fasciocutaneous free flap and artery conduit of coronary artery bypass graft procedure. Even though Allens' test has been used for evaluating the patency of radial artery, the studies on the correlations between risk factors for atherosclerosis and histopathologic findings of radial arteries are rare, until now. Therefore, the authors investigated the correlations between these two factors, and tried to estimate the feasibility of the radial artery in high-risk groups for artherosclerosis. The risk factors for atherosclerosis and lipid profiles were investigated in 38 patients by history taking, physical examinations and blood analysis. And 38 cases of segments of vessel were harvested during the elevation of the flap. The degrees of vessel medial sclerosis were estimated by R values(by Kobayashi and colleagues) that is the median value between the thickness of the intima and that of the media. The measured mean R value was $0.210{\pm}0.05$. Thirty one cases belonged to Grade I(R<0.25), 7 cases belong to Grade II(0.25

• 한국육종학회지
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• 제41권4호
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• pp.391-396
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• 2009

Perilla frutescens, which belonging to the Labiatae family, is widely cultivated oil crop and have been used traditional herbal medicine in East Asia such as Korea, China, and Japan. Especially, the leaves and the seeds of this species are important in Korean traditional cooking, as one of the popular garnish and food colorants. Numerous studies have revealed that the beneficial health effects of perilla are due to its several phytochemicals contents, such as rosmarinic acid, caffeic acid, luteolin, and apigenin. For this reason, increasing the content of phytochemicals in perilla hasbecome a major breeding objective. The genetic diversity of the rosmarinic acid, caffeic acid, luteolin, and apigenin content in perilla seed is poorly documented. We analyzed the rosmarinic acid, caffeic acid, luteolin, and apigenin content of 203 accessions of perilla germplasm by high performance liquid chromatography (HPLC). The rosmarinic acid and luteolin contents ofgermplasms were ranged from $15.7{\mu}g/g$ to $2717.1{\mu}g/g$ and from $1.6{\mu}g/g$ to $582.4{\mu}g/g$ respectively.

• 한국정보통신학회논문지
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• 제23권8호
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• pp.966-974
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• 2019

본 연구에서는 저전력 영역에서의 효율을 개선하기 위해 바이패스 구조를 갖춘 2.4GHz CMOS 전력 증폭기를 제안한다. 바이패스 구조를 설계하기 위해, 구동 증폭단의 공통 게이트 트랜지스터를 두 개로 분할하였다. 공통 게이트 트랜지스터 중 하나는 고출력 전력 모드를 위한 전력단을 구동하도록 설계된다. 다른 공통 게이트 트랜지스터는 저출력 전력 모드를 위해 전력단을 바이 패스하도록 설계하였다. 측정 된 최대 출력은 20.35 dBm이며 효율은 12.10 %이다. 11.52 dBm의 측정 된 출력에서 효율은 전력증폭단을 바이 패스함으로써 1.90 %에서 7.00 %로 향상됨을 확인하였다. 측정 결과를 바탕으로 제안 된 바이 패스 구조의 타당성을 성공적으로 검증 하였다.

• 대한지역사회영양학회지
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• 제26권1호
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• pp.23-36
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• 2021

Objectives: This study sought to assess the prevalence and duration of weight-control or health functional food use, associated weight-control behavior, perception, and knowledge among university students. Methods: The subjects were 442 university students in Cheonju, Korea, and data was collected by a self-administered questionnaire. Both χ2 and t-tests were conducted for categorical and mean comparisons. Results: An estimated 62.7% (female 69.0%, male 54.8%) had ever attempted weight-control. Among these, an estimated 59.2% of females and 38.9% of males had used weight-control or health functional foods with significant gender difference. The weight-control foods commonly used included chicken breast, protein powder, low-fat milk and soymilk, and meal replacement drinks, while garcinia cambogia extract and green tea extract were frequently used as health functional foods. One of 10 (10.3%) consumers of weight-control foods reported ≥ 7 months use, with less frequent long-term consumption of health functional foods (4.2%). The average degree of satisfaction was 3.24 ± 0.92 for weight-control foods and 2.72 ± 0.97 for health functional foods on a 5-point scale, meaning 'slightly satisfied' and 'slightly dissatisfied', respectively. Females or students with an experience of weight-control reported poorer perceptions of their health and body image as well as a higher need for weight control. Besides, both male and female subjects felt a high need for correct information regarding weight-control methods. Conclusions: Our results provide a better understanding of the characteristics associated with the use of weight-control or health functional foods among university students and will be useful in developing a nutrition education program by incorporating correct body image, knowledge, and practical yet desirable practices for weight control.

• 전기전자학회논문지
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• 제26권4호
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• pp.722-727
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• 2022

본 논문에서는 0.25 ㎛의 게이트를 갖는 AlGaN/GaN HEMT를 기반으로 개발된 X-대역 전력 증폭기 MMIC의 특성을 기술한다. 개발된 X-대역 전력 증폭기 MMIC는 9 GHz~10 GHz의 주파수 대역에서 21.6 dB 이상의 소신호 이득과 46.11dBm(40.83 W) 이상의 출력 전력을 가진다. 전력 부가 효율 특성은 43.09%~44.47%이며 칩의 크기는 3.6 mm×4.3 mm이다. 출력 전력 밀도는 2.69 W/mm²를 나타내었다. 개발된 AlGaN/GaN 전력 증폭기 MMIC는 다양한 X-대역 레이더 응용에 적용 가능하다.