• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2008년도 추계학술대회 논문집 Vol.21
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• pp.172-173
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• 2008

In this study, $0.95(K_{0.5}Na_{0.5})NbO_3$-0.05Li$(Sb_{0.8}Nb_{0.2})O_3$ + $Ag_2O$ + x wt% $MnO_2$ were investigated as a function of the amount of $MnO_2$ addition in order to improve dielectric and piezoelectric properties of Lead-free piezoelectric ceramics. With increasing the amount of $MnO_2$ addition, density and electromechanical coupling factor $(k_p)$ increased up to 0.3wt.% $MnO_2$ and decreased above 0.3wt.% $MnO_2$. At the sintering temperature of 1020 $^{\circ}C$, Electromechanical coupling factor $(k_p)$, density, dielectric constant $({\varepsilon}r)$ and mechanical quality factor $(Q_m)$ of composition ceramics with 0.4wt% $Ag_2O$ addition showed the optimal value of 0.431, 4.33 g/$cm^3$, 820 and 119, respectively.

• 한국의류학회지
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• 제20권1호
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• pp.98-112
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• 1996

Tho purpose of this study was to investigate hygienic and comfortable properties of socks. Materials are nine summer socks either frequently being worn or new products recently introduced to market. Three female and three male adults participated in this study. Through wearing experiment, the numbers of microbes on foot and sock were counted and subjective sensation was measured. The microbes were isolated and identified based on growth physiological characteristics. Nine different socks had smaller number of bacteria of sock than that of foot. The number of bacteria of sock was significantly related with that of foot in cotton socks, in piled cotton socks, in mesh cotton socks, in cotton+ nylon+ linen blended socks, in nylon socks. Total number of bacteria of tv cut finished socks was most small and total number of bacteria was increased in the order of ultra fresh finished socks, untreated cotton socks, nylon socks, cotton + nylon+ linen blended socks, mesh cotton socks, polyester+ nylcn+ linen blended socks, piled cotton socks, cotton socks. Total number of bacteria of cotton socks and piled cotton socks were significantly different from that of uv cut finished socks. Finished socks and .jocks has high air permeability had significantly small number of bacteria. Comfortable sensation in nylon socks and polyester+nylon+linen socks was significantly uncomfortable. The way socks finished and air permeability of .jocks affected theirs hygienic property, while fiber type of them affected comfortablene, is. Bacteria identified were Staphylo coccus aureus, S. au rice larir, S. cahn ii, S. ep ids midis, S. haemo Iyticus, S. h am in 2's. S.fapraphyticus, S. warnery, 1 cinetobater calcoaceticus bio. anitratus, p.reudomonas mendocina, p. paucimobilis, Flavimonas Q ryzihabitans (CDC Group VE-2), and Xanthomanas maltophina. Fungi isolated were Spicaria sp., Thrichoderma sp., Fusarium sp., Aspergillus sp., Epicoccum sp., Cladosporium sp., and Penicillium sp..

• 한국전기전자재료학회논문지
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• 제21권2호
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• pp.126-130
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• 2008

In this study, in order to develop low loss multilayer piezoelectric actuator, PZN-PZT ceramics were fabricated using $Li_2CO_3,\;Bi_2O_3$, CuO and ZnO as sintering aids, their structural, piezoelectric and dielectric characteristics were investigated according to the amount of ZnO addition, At the sintering temperature of $870^{\circ}C$, the density, electromechanical coupling factor(kp), mechanical quality factor(Qm), dielectric constant(${\epsilon}_r$) and piezoelectric constant($d_{33}$) of 0.4 wt% ZnO added specimen (sintered at $870^{\circ}C$) showed the optimum value of $7.812g/cm^3$, 0.535, 916, 1399, 335 pC/N respectively. Taking into consideration above piezoelectric properties of the specimen sintered at low temperature, it was concluded that PZN-PZT ceramics using 0.4 wt% ZnO as additive showed the optimum characteristics as the composition ceramics for low loss multilayer piezoelectric actuator application.

• 디지털융복합연구
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• 제15권2호
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• pp.251-262
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• 2017

본 연구는 Bronfenbrenner의 생태학적 체계이론을 바탕으로 대학생의 정신건강에 영향을 미치는 요인을 구분하고 통합적인 모형 구축과 정신건강 증진을 위한 간호중재 개발의 기틀을 마련하고자 한다. 연구방법은 횡단적 조사연구로 대학생을 대상으로 하였다. 일반적 특성 및 정신건강관련 특성은 SPSS 20.0 프로그램을, 모형의 적합도검증, 가설검증은 Amos 20.0 프로그램을 이용하였다. 연구결과에서 모형의 적합도 지수는 $x^2=614.90$(p=.000), Q값=3.5, GFI=.88, AGFI=.84, NFI=.92, NNFI=.94, CFI=.94, RMR=.02, RMSEA=.08 적합도를 나타내어 연구모형이 가정에 적합한 것으로 나타났다. 연구결과 정신건강에 스트레스가 가장 높은 영향을 미치고 있으며 스트레스 대처 방안과 자아 존중감, 부모의 양육태도가 정신건강에 영향을 미치는 것으로 확인되었다. 대학생의 정신건강을 증진시키기 위해서는 스트레스 관리, 자아존중감 증진, 스트레스 대처 능력 향상을 도모하는 간호중재를 개발하고, 학교현장 및 정신보건 실무에 활용하는 중재가 수행되어야 할 것으로 생각된다.

• Journal of Ecology and Environment
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• 제42권4호
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• pp.308-316
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• 2018

Background: Genus Sasa, dwarf bamboos, are considered to be species that lower biodiversity in the temperate forests of East Asia. Although they have a long interval, they, the monocarpic species, have a unique characteristic of large-scale synchronized flowering. Therefore, once they have flowered and then declined, it may be an opportunity for suppressed surrounding species. A previous study reported that Sasa borealis showed specialized flowering nationwide with a peak in 2015. However, this was based on data from a social network service and field survey at Mt. Jeombong. Therefore, we investigated S. borealis in the forests of five national parks in order to determine whether this rare synchronized flowering occurred nationwide, as well as its spatial distribution. Results: We found a total of 436 patches under the closed canopy of Quercus mongolica-dominated deciduous forests in the surveyed transects from the five national parks. Of these patches, 75% occupied a whole slope area, resulting in an enormous area. The patch area tended to be larger in the southern parks. Half (219 patches) of the patches flowered massively. Among them, 76% bloomed in 2015, which was consistent with the results of the previous report. The flowering rate varied from park to park with that of Mt. Seorak being the highest. The culms of the flowering patches were significantly taller (F = 93.640, p < 0.000) and thicker (F = 61.172, p < 0.000). Following the event, the culms of the flowering patches declined, providing a good opportunity for the suppressed plant species. The concurrent massive flowering of the mature patches was believed to be triggered by some stress such as a spring drought. Conclusion: We confirmed that the rare synchronized flowering of S. borealis occurred with a peak in 2015 nationwide. In addition, we explored that S. borealis not only monopolized an enormous area, but also dominated the floors of the late-successional Q. mongolica-dominated deciduous forests. This presents a major problem for Korean forests. As it declined simultaneously after flowering, there are both possibilities of forest regeneration or resettlement of S. borealis by massively produced seeds.

• 한국농공학회논문집
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• 제63권1호
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• pp.61-73
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• 2021

Recently, the deterioration of water quality in Wonju stream has been reported due to the increase in diverse pollution sources along with community development and urbanization. Various types of attempts with a huge budget were made for better water quality so far, but its effectiveness is still doubted. In order to establish site-oriented measures for water quality improvement, the topographic and hydrologic factors were evaluated based on site inspection and survey. As the major streams merged into the Wonju stream, the Hwa and Heungyang streams were found to have higher pollution loads and contributions compared to other streams due to the scattered livestock farms and industries, and vulnerable land use. Notably, the discharge water from the Wonju Public Sewage Treatment Plant had the highest level of pollution load, impacting on the water quality of Wonju Stream. According to the SWAT model as water quality measures, the improvement effect of water quality in this treatment plant can be reached to the reductions in BOD 11.06%, T-N 23.56%, T-P 10.60% when the proper managements applied, whereas the improvement of water quality would be 3.89%, 1.23%, and 3.32% for BOD, T-N, T-P, respectively, for the industries. The reduction of the livestock industry was generally very high as a pollution source, but it was not much higher at the end of Wonju Stream than other measures. These results recommended that the water q uality improvement measures should be designated for each upper-middle-lower section in Wonju stream.

• 대한치과보철학회지
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• 제44권6호
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• pp.690-698
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• 2006

Statement of problems. The heat produced during polymerization of polymer-based provisional materials may cause thermal damage to the vital pulp. Purpose. This study was performed to evaluate the exotherm reaction of the polymerbased provisional materials during polymerization by differential scanning calorimetry and to compare the temperature changes of different types of resins. Material and methods. Three dimethacrylate-based materials (Protemp 3 Garant, Luxatemp Plus, Luxatemp Fluorescence) and five monomethacrylate- based material (Snap, Alike, Unifast TRAD, Duralay, Jet) were selected. Temperature changes of polymer-based provisional materials during polymerization in this study were evaluated by D.S.C Q-1000 (TA Instrument, Wilmington, DE, USA). The following three measurements were determined from the temperature versus time plot: (1) peak temperature, (2) time to reach peak temperature, (3) heat capacity. The data were statistically analyzed using one-way ANOVA and multiple comparison Bonferroni test at the significance level of 0.05. Results. The mean peak temperature was $39.5^{\circ}C({\pm}\;1.0)$. The peak temperature of the polymer-based provisional materials decreased in the following order: Duralay > Unifast TRAD, Alike > Jet > Luxatemp Plus, Protemp 3 Garant, Snap, Luxatemp Fluorescence. The mean time to reach peak temperature was 95.95 sec $({\pm}\;64.0)$. The mean time to reach peak temperature of the polymer-based provisional materials decreased in the following order: Snap, Jet > Duralay > Alike > Unifast TRAD > Luxatemp Plus, Protemp 3 Garant, Luxatemp Fluorescence. The mean heat capacity was 287.2 J/g $({\pm}\;107.68)$. The heat capacity of the polymer-based provisional materials decreased in the following order: Duralay > TRAD, Jet, Alike > Snap, Luxatemp Fluorescence, Protemp 3 Garant, Luxatemp Plus. Conclusion. The heat capacity of materials, determined by D.S.C., is a factor in determining the thermal insulating properties of restorative materials. The peak temperature of PMMA was significantly higher than others (PEMA, dimethacrylate). No significant differences were found among PEMA (Snap) and dimethacrylate (P >0.05). The time to reach peak temperature was greatest with PEMA, followed by PMMA and dimethacrylate. The heat capacity of PMMA was significantly higher than others (PEMA, dimethacrylate). No significant differences were found among PEMA and dimethacrylate (P >0.05).

• KIEE International Transactions on Electrophysics and Applications
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• 제5C권3호
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• pp.102-110
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• 2005

Piezoelectric transformers(PT) are expected to be small, thin and highly efficient, and which are attractive as a transformer with high power density for step down voltage. For these reasons, we have attempted to develop a step-down PT for the miniaturized adaptor. We propose a PT, operating in thickness extensional vibration mode for step-down voltage. This PT consists of a multi-layered construction in the thickness direction. In order to develop the step-down PT of 10 W class and turn ratio of 0.1 with high efficiency and miniaturization, the piezoelectric ceramics and PT designs are estimated with a variety of characteristics. The basic composition of piezoelectric ceramics consists of ternary yPb(Zr$_{x}$Ti$_{1-x}$)O$_{3}$-(1-y)Pb(Mn$_{1/3}$Nb1$_{1/3}$Sb$_{1/3}$)O$_{3}$. In the piezoelectric characteristics evaluations, at y=0.95 and x=0.505, the electromechanical coupling factor(K$_{p}$) is 58$\%$, piezoelectric strain constant(d$_{33}$) is 270 pC/N, mechanical quality factor(Qr$_{m}$) is 1520, permittivity($\varepsilon$/ 0) is 1500, and Curie temperature is 350 $^{\circ}C$. At y = 0.90 and x = 0.500, kp is 56$\%$, d33 is 250 pC/N, Q$_{m}$ is 1820, $\varepsilon$$_{33}$$^{T}$/$\varepsilon$$_{0}$ is 1120, and Curie temperature is 290 $^{\circ}C$. It shows the excellent properties at morphotropic phase boundary regions. PZT-PMNS ceramic may be available for high power piezoelectric devices such as PTs. The design of step-down PTs for adaptor proposes a multi-layer structure to overcome some structural defects of conventional PTs. In order to design PTs and analyze their performances, the finite element analysis and equivalent circuit analysis method are applied. The maximum peak of gain G as a first mode for thickness extensional vibration occurs near 0.85 MHz at load resistance of 10 .The peak of second mode at 1.7 MHz is 0.12 and the efficiency is 92$\%$.

• 한국식품영양과학회지
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• 제41권9호
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• pp.1235-1241
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• 2012

시판중인 14종의 식용버섯을 전체(E), 갓(P), 대(S)의 부위별로 분류하여 DPPH와 ABTS 라디칼 소거능에 따른 항산화활성과 이들 활성의 근거물질인 총 페놀, 플라보노이드, 그리고 유비퀴논 함량을 측정하였다. 시판버섯의 갓 부위(P)에 함유된 총 페놀함량은 193.9~536.6 mg/100 g으로 대 부위(S)의 156.8~370.8 mg/100 g보다 23.4~44.7% 높게 나타났다. 총 플라보노이드 함량은 quercetin의 동량 값으로 표시했을 때 전체 부위(E)에서 14.8~31.2 mg/100 g으로 나타나 총 페놀함량에 비해 매우 낮은 함량으로 측정되었다. 유비퀴논 함량 역시 갓 부위(P)가 163.5~485.1 ${\mu}g$/100 g으로 나타나 대 부위(S)의 65.6~142.9 ${\mu}g$/100 g에 비해 2.5~3.4배 더 높은 것으로 측정되어 시판버섯에 함유된 유효활성 성분은 주로 자실체의 주름부위에 분포된 것을 알 수 있다. 시료(10mg/mL)의 80% 메탄올 추출물의 DPPH와 ABTS 자유 라디칼 소거능에 따른 전체 부위(E)의 항산화활성은 각각 51.2~90.1%와 62.5~95.8%로 비교적 높게 나타났다. 특히 상황버섯의 라디칼 소거능은 평균 92.7%로 나타나 전체 부위(E)의 시판버섯 중 가장 높았으며 목이버섯은 평균 56.9%로 나타나 항산화활성이 가장 낮게 나타났다(p<0.05). 이 같은 결과는 각 부위별 자체 내 함유된 평균 총 페놀함량($R^2=0.080$) 및 유비퀴논 함량($R^2=0.55$)과 유의적인 상관관계(p<0.05)를 나타내어 이들 성분이 항산화활성에 영향을 미친 것으로 추정된다.

• 한국환경생태학회지
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• 제31권2호
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• pp.202-219
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• 2017

본 연구는 금수산 일대의 군집구조를 파악하여 생태적 보전과 관리의 기초자료제공 목적으로 수행되었다. 2016년 6월부터 2016년 11월까지 식물사회학적으로 식생조사를 하였으며, 41개소의 방형구를 설정하여 식생유형분류, 중요치, 일치법을 적용하여 분석하였다. 산림식생 분석결과, 신갈나무군락군에서 군락단위로 층층나무군락, 밤나무군락(식생단위 3), 굴참나무군락(식생단위 4), 신갈나무전형군락(식생단위 5)으로 분류되었으며, 층층나무군락은 느릅나무군(식생단위 1)과 담쟁이덩굴군(식생단위 2)으로 세분되었다. 평균상대중요치는 식생단위 1에서 물푸레나무 14.9%, 산뽕나무 8.7%, 고로쇠나무 8.3% 순으로 나타났고, 식생단위 2는 일본잎갈나무 23.2%, 층층나무 20.1%, 담쟁이덩굴 6.5% 순으로 나타났다. 식생단위 3은 신갈나무 15.8%, 밤나무 13.4%, 물푸레나무 9.8% 순으로 나타났고, 식생단위 4는 신갈나무 26.6%, 굴참나무 20.8%, 소나무 16.6% 순으로 나타났으며, 식생단위 5는 신갈나무 48.3%, 쪽동백나무 7.5%, 물푸레나무 5.3% 순으로 나타났다. 일치법 분석의 결과로서 식생단위는 해발 700m, 경사 $20^{\circ}$, 지형은 사면중, 암석노출도 20%, 출현종수 30종, 교목층 식피율 80%, 교목층 수고 20m를 기준으로 분류되었다. 따라서 금수산 일대의 생태학적이고 지속가능한 산림식생관리를 위해서는 분류되어진 식생단위에 따라 차별화된 관리방법의 도출이 필요할 것으로 판단되었다.