• 한국수산과학회지
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• 제50권1호
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• pp.55-64
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• 2017

Seasonal variability in algal community structure was examined at the intertidal zones of five study sites on the Taean Peninsula, on the western coast of Korea, from February 2014 to November 2015. A total of 118 species of marine algae, comprising 17 green, 24 brown and 77 red algae, were identified. The maximum number of species was observed at the Mohang site (75 species), and the minimum at the Yeonpo site (46 species). The seaweed biomass was $160.24g\;dry\;wt./m^2$ on average, and was maximal at Uihang ($519.04g\;dry\;wt./m^2$) and minimal at Yeonpo ($19.03g\;dry\;wt./m^2$). Based on biomass, the dominant seaweeds at Taean peninsula were Sargassum thunbergii and Corallina pilulifera. Community indices were as follows: richness index (R), 3.21-5.01; evenness index (J'), 0.33-0.38; and diversity index (H'), 0.90-1.12. Based on evaluation of the environmental states by the community indices, the ecological evaluation index (EEI) of Taean peninsula was "moderate". The overall species and biomass of seaweeds decreased after the oil spill. However, Hakampo previously showed a similar algal community structure. In conclusion, the algal community was temporarily affected by the oil spill, but rapidly recovered.

• The Journal of Advanced Prosthodontics
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• 제7권1호
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• pp.56-61
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• 2015

PURPOSE. The purpose of this study was to evaluate the effects of the surface treatment and shape of the dental alloy on the composition of the prosthetic work and its metallic ion release in a corrosive medium after casting. MATERIALS AND METHODS. Orion Argos (Pd-Ag) and Orion Vesta (Pd-Cu) were used to cast two crowns and two disks. One of each was polished while the other was not. Two as-received alloys were also studied making a total of 5 specimens per alloy type. The specimens were submersed for 7 days in a lactic acid/sodium chloride solution (ISO standard 10271) and evaluated for surface structure characterization using SEM/EDAX. The solutions were quantitatively analysed for the presence of metal ions using ICP-MS and the results were statistically analysed with one-way ANOVA and a Tukey post-hoc test. RESULTS. Palladium is released from all specimens studied (range $0.06-7.08{\mu}g{\cdot}cm^{-2}{\cdot}week^{-1}$), with the Pd-Cu alloy releasing the highest amounts. For both types of alloys, ion release of both disk and crown pairs were statistically different from the as-received alloy except for the Pd-Ag polished crown (P>.05). For both alloy type, disk-shaped pairs and unpolished specimens released the highest amounts of Pd ions (range $0.34-7.08{\mu}g{\cdot}cm^{-2}{\cdot}week^{-1}$). Interestingly, in solutions submerged with cast alloys trace amounts of unexpected elements were measured. CONCLUSION. Shape and surface treatment influence ion release from dental alloys; polishing is a determinant factor. The release rate of cast and polished Pd alloys is between $0.06-0.69{\mu}g{\cdot}cm^{-2}{\cdot}week^{-1}$, which is close to or exceeding the EU Nickel Directive 94/27/EC compensated for the molecular mass of Pd ($0.4{\mu}g{\cdot}cm^{-2}{\cdot}week^{-1}$). The composition of the alloy does not represent the element release, therefore we recommend manufacturers to report element release after ISO standard corrosion tests beside the original composition.

• 한국전기전자재료학회논문지
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• 제25권11호
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• pp.867-872
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• 2012

In this study, in order to develop excellent lead free piezoelectric ceramics for piezoelectric actuators application, $Li_{0.04}(Na_{0.50}K_{0.50})_{0.96}[(Nb_{0.86}Ta_{0.10}Sb_{0.04})_{0.994}Co_{0.015}]O_3+0.0025SrO+0.15\;wt%K_2CO_3+x\;wt%Nb_2O_5$ (x = 0 - 0.5 wt%) (abbreviated as LNKNTSCS-xN) ceramics were fabricated by a conventional sintering technique. the phase structure, microstructure and electrical properties were investigated with a emphasis on the influence of the $Nb_2O_5$ content. High electrical properties of $d_{33}$=234 pC/N, kp=0.392, ${\varepsilon}_r$=1,395, ${\rho}=4.70g/cm^3$ were obtained from the specimen with x=0.4 wt%, which suggests that the composition ceramics is a promising lead-free piezoelectric material.

• 자원환경지질
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• 제40권6호
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• pp.761-769
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• 2007

경기도, 강원도, 충청도 일대에서 화성암, 변성암, 퇴적암의 총 712개의 암석을 채취하여 열물성을 측정하였다. 측정 결과로 화성암의 평균 열전도도는 3.58W/m-K, 변성암은 4.16W/m-K, 퇴적암은 4.53W/m-K이다. 우리나라의 경우 화강암과 편마암이 주를 이루고 있는데 이에 대한 열물성 값을 보면 화강암의 열전도도는 2.13-5.87W/m-K의 범위를 가지며, 평균 열전도도는 3.57W/m-K, 편마암은 2.26-6.67W/m-K의 범위를 가지며, 평균 열전도도는 3.945W/m-K이다. 화강암의 평균 열확산율은 $1.43mm^2/sec$, 비열은 0.914J/gK, 편마암의 평균 열확산율은 $1.55mm^2/sec$, 비열은 0.912J/gK로 나타났다. 일반적으로 같은 암석의 열전도도 값의 범위가 큰 이유는 암석의 구성광물, 이방성 등에 영향을 받기 때문이다.

• 한국세라믹학회지
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• 제48권1호
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• pp.63-68
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• 2011

The investigation is directed to lead free (Pb-free) frits that can be used for organic light emitting diode, plasma display screen devices and other sealing materials. $P_2O_5$-SnO system glasses have been prepared for Pb-free low temperature glass frit. Structure and properties of the glasses with the composition SnO-$xB_2O_3-(60-x)P_2O_5$ (x=0, 5, 10, 15, 20, 25, 30, 35, 40 mol%) were characterized by infrared spectra (IR), X-ray diffraction(XRD), Density, Molar volume, Thermo mechanical analysis(TMA) and weight loss after immersion test. Glass transition temperature($T_g$), dilatometric softening temperature($T_d$) and chemical durability increased, and coefficient of thermal expansion($\alpha$) decrease with the substitution of $B_2O_3$ for $P_2O_5$ in the range of 0~25 mol%.

• 폴리머
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• 제31권6호
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• pp.461-468
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• 2007

폴리에스터와 trisilanolisobutyl polyhedral oligomeric silsesquioxane(TBPOSS)으로 제조된 나노복합재료에 존재하는 응집체의 구조를 이해하기 위하여 SEM-EDS 분석과 1,1,1,3,3,3-hexafluoro-2-propanol(HFIP) 용매에 녹인 뒤 레이저 광산란법이 실시되었다. SEM에서 평균 직경 120 nm로 나타난 구형 응집체는 가교화된 마이크로겔이 아니라, 320개의 TBPOSS 분자들과 폴리에스터 분절들이 교대로 연결된 선형 중합체 사슬(무게평균 분자량=$2.3{\times}10^6\;g/mol$)이며, 이들은 매트릭스의 폴리에스터와의 화학조성 차이 때문에 상분리된 것으로 여겨진다. 반면에 무게평균 분자량이 $4.0{\times}10^4\;g/mol$인 매트릭스의 폴리에스터는 분자당 2.5개의 TBPOSS 분자를 포함하고 있는 것으로 나타났다. 또한 넣어준 TBPOSS의 약 93%가 매트릭스에 존재하며 나머지 7%는 구형 응집체에 분포하고 있다는 것도 밝혀졌다.

• Journal of Plant Biology
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• 제26권4호
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• pp.181-190
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• 1983

Seasonal occurrence of benthic algae and changes of subtidal vegetation were studied for their species composition, diversity and biomass during 1982 and 1983 at several selected sites at Juckdo Island (38$^{\circ}$12'N, 128$^{\circ}$32'E), eastern coast of Korea. Three large brown algae which played a role in change of algal vegetation through their great biomass were investigated with regard to their seasonal growth. Large brown algae such as Undaria pinnatifida, Costaria costata, Laminaria japonica, Agarum cribrosum, Sargassum confusum and S. hornerii constitute the major portion of vegetation in this area throughout the year. Algal vegetation in spring time is characterized by dominance of species U. pinnatifida and C. costata, whereas the summer vegetation by S. confusum and S. hornerii. In autumn large brown algae are shedded and only small algae, such as Chondrus ocellatus and Grateloupia filicina, remain. The vegetation in winter is dominated by the growth of U. pinnatifida and C. costata. Monthly changes in mean length and weight of randomly collected U. pinnatifida, C. costata and S. confusum are as follows; U. pinnatifida occurs from December to June and shows their maximum growth during March (120 cm in length, 201 g/individual in wet weight), its maximum growth rate is 1.4 cm/day, 3.3 g/day in this month. The growth season of C. costata is very similar to U.pinnatifida, but their average maximum length(110 cm) and weight (106 g/ind.) are lower than U. pinnatifida. The greatest growth rate is during March (1.8 cm/day, 2.0g/day). S. confusum is present throughout the year and reaches the maximum growth (102 cm, 63g/ind.) in July. Maximum growth rate (1.5 cm/day, 1.2 g/day) occurs also during this month. U. pinnatifida and C. costata show different months of maximum growth evidently during the two year. This seems to be caused by a considerable damage to the local vegetation followed by heavy storm in February 1983.

• 한국환경과학회지
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• 제31권11호
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• pp.993-997
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• 2022

This study was conducted to evaluate the structure and composition (i.e., pH, moisture, total-N, pathogens, and volatile fatty acids) of broiler and duck manure treated with larvae of three insect larvae, namely, Tenebrio molitor, Protaetia brevitarsis seulensis, and Ptecticus tenebrifer. Hatched Tenebrio molitor (n=300), Protaetia brevitarsis seulensis (n=60), and Ptecticus tenebrifer (n=300) were used in this study; specially, the larvae were divided into six treatments with three replicates. The treatments were as follows: T1: 110 g broiler manure + Tenebrio molitor larvae (n=50), T2: 110 g duck manure + Tenebrio molitor larvae (n=50), T3: 125 g broiler manure + Protaetia brevitarsis seulensis larvae (n=10), T4: 125 g duck manure + Protaetia brevitarsis seulensis larvae (n=10), T5: 105 g broiler manure + Ptecticus tenebrifer larvae (n=50), and T6: 105 g duck manure + Ptecticus tenebrifer larvae (n=50). For all the larval treatments, the following results were observed: The moisture content of the duck manure treat with three insect larvae was higher than that of the broiler manure (p<0.05), whereas broiler manure had a higher pH (p<0.05). In addition, the total nitrogen content of broiler manure was higher than that of duck manure (p<0.05). However, the insect larvae did not significantly affect pathogens (E.coli and Salmonella) and the volatile fatty acids (p>0.05). In conclusion, the use of the three insect larvae to create organic nitrogen compost using poultry manure is feasible.

• Journal of Magnetics
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• 제4권4호
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• pp.119-122
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• 1999

Magnetic properties and crystal structures of (Fe1-XCoX) Pt (X = 0, 0.2, 0.4, 0.5, 0.6, 0.8 and 1.0) ternary thin films were investigated. The order-disorder phase transformation of FePt thin films during annealing was also studied by x-ray diffraction and M ssbauer spectroscopy. The magnetic thin films were deposited on glass substrates using a dc sputtering method and were subsequently annealed at 400~$700^{\circ}C$ in a high vacuum. The as-deposited films exhibited a high degree of the <111> preferred orientation and the preferred orientation was not destroyed even after the subsequent post annealing. The coercivity of the ($Fe_xCo_{1-x}$) Pt thin films annealed at $700^{\circ}C$ showed a minimum value at the equiatomic composition of the Fe and Co atoms. The ordered structure of the FePt alloy was thought to have formed from the disordered structure by an inhomogeneous process, which was confirmed by the asymmetric peak shapes and M ssbauer spectra.

• 한국초지조사료학회지
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• 제22권3호
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• pp.187-194
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• 2002

다양한 관리하의 방목초지 식물군낙에 대한 생태적 특성과 군락간의 유사성을 검정하고자, 1998년 8월부터 10월까지 독일의 중부지역인 Witzenhausen 근교에서 조사한 초지 식물군락을 Kassel 대학교 초지생태ㆍ사료작물연구소에서 컴퓨터 프로그램을 이용하여 분석하였던 바, 그 결과를 요약하면 다음과 같다. 1. 10개 지역의 초지에서 조사한 식생을 군강(class)으로 분류한 식물군낙은 Molinio-Arrhenatheretea 초지 이었으며, 초지 식물군락의 사료가는 4.35∼6.60으로 군락에 따라 다소 차이가 있었으나 대부분 중상급 이었다. 2. 모든 군락의 주요 생활형은 Hemikryptophye 이었으며, 해할구조는 Mesomorphic이었다. 3. 식물군낙간 정의 상관은 3과 4번 군락이 가장 높았고, 8면과 10번 군락간에는 상관이 없었으며, 8면과 9번 군락간에는 아주 작은 부의 상관이 있었다. 4. 단분석의 유사성 범위는 유클러드 거리계수 0.0∼54.0이며, 평균 유사성은 38.7로서 이때 유사성이 큰 식생그룹은 (8, 7, 6), (10, 9, 5), (4, 3), (2, 1) 등 4개 군단으로 분류할 수 있으며, 9면과 10면 군낙의 유사성이 유클리드 거리계수 16.0으로 가장 높았다.