• 자원환경지질
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• 제46권5호
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• pp.445-453
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• 2013

의성 탑리리 오층석탑(국보 제77호)은 통일신라시대의 대표적인 석조문화재이다. 현재 이 석탑은 지속적인 풍화로 인해 전체적으로 흑색, 황색, 백색변색이 발생되어 있으며 백색변색이 발생한 부분에서 미세균열, 박리박락, 입상분해가 집중적으로 분포해 있다. 표면오염물에 대한 분석결과, 흑색변색은 망간산화물, 황색변색은 철산화물, 백색변색은 석고와 타라나카이트로 인해 발생한 것으로 확인하였다. 또한, 석탑에 발생한 물리적 훼손은 암석내부에서 석고의 결정화 작용으로 인해 발생한 것으로 판단된다. 따라서 의성 탑리리 오층석탑을 장기적으로 보존하기 위해서는 보존처리 매뉴얼에 따라 석고를 중심으로 표면오염물을 제거하고 P-XRF를 활용한 정기적인 모니터링이 요구된다.

• 한국해양공학회지
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• 제24권5호
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• pp.60-66
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• 2010

Zinc has a number of characteristics that make it well suited for use as a coating to protecting iron and steel products from corrosion. Its excellent corrosion resistance in most environments accounts for its successful use as a protective coating on a variety of products and in many exposure conditions. The excellent field performance of zinc coatings results from their ability to form dense, adherent films that corrode at a rate that ranges from 1% to 10% of the corrosion rate of ferrous materials, depending on the environment. Recently, EU RoHS and EU ELV prohibited the use of materials that adversely affect the environment, such as Pb, Hg, Cd, and $Cr^{+6}$. In this study, environmentally-friendly, Cr-free solutions (epoxy solution, acrylic solution, and urethane solution S-700) and organic/inorganic solution with Si; LRO-317) were used to evaluate the corrosion resistance of zinc-coated steel subjected to a saltwater spray for 72 hours. The coating of urethane solution (S-700) was best among the three kinds of solution with heat treatment during five minutes at $190^{\circ}F$. Test specimens with S-700 and LRO-317 coating were heat treated in a drying oven at 170, 180, 190, 200, and $210^{\circ}C$ for five minutes. The results show that the optimum corrosion resistance was $190^{\circ}C$ in EGI and $170^{\circ}C$ in HDGI, respectively.

• Journal of Nutrition and Health
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• 제18권3호
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• pp.194-200
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• 1985

The purpose of this study was to investigate sodium intake and protein metabolism for pregnant women in Korea. The relationship between salt consumption and hypertension, electrolyte changes in pregnancy, and the tendency of weight gain of pregnant women were also examined. The dietary survey and twelve or twenty-four hour's urine collection was performed in this study. The subjects were pregnant women who came to gynecology clinic for prenatal care from July to August in 1984. The results were as follows: 1) Intakes of calorie and iron of Korean pregnant women were 2,036 Kcal and 16mg per day per person. The calorie composition consists of 65% carbohydrate, 16% protein, and 19% lipids. The average level of all nutrients was about 87% of Korean Recommended Dietary Allowances. 2) The sodium intakes in pregnant women estimated by dietary survey was 318.6 mEq Na (7,966 mg Na), which is equivalent to 20.2 g NaCl. 3) Daily sodium excretion was 112.5 mEq per liter, that is equal to 147.4 mEq. Potassium excretion was 24.95 mEq per liter and creatinine excretion was 594.0 mg per day. 4) There were statistically significant correlations between sodium intake and the excretions of sodium, potassium and creatinine. The blood pressure was positively correlated with sodium intakes. As sodium and potassium ratio was increased, systolic blood pressure and diastolic blood pressure were also significantly increased 5) Urinary nitrogen and creatinine ratio known to be reliable index for nutritional status of protein was 5.5 : 1. These values were comparable to the values in American pregnant women. 6) The weight gain during the pregnancy was examined. There was little weight gain during the first trimester, because of nausea, vomit and decrease of appetite. The weight gain during the second trimester was 4.9Kg, and 11.1Kg for third trimester.

• 한국주조공학회지
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• 제32권2호
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• pp.104-108
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• 2012

The effect of heat treatment on mechanical properties of 0.4C-2.3Si(wt%) steel with bainitic ferrite matrix were investigated. This steel has been synthesized intergrating concepts from TRIP(Transformation Induced Plasticity) steel & Austempered Ductile Cast Iron(ADI) technology. The low alloy medium carbon (0.4 %C) steel with high silicon (2.3 %Si) was initially annealed for 60 min at $800^{\circ}C$, $820^{\circ}C$ and $840^{\circ}C$ respectively in the intercritical region and then subsequently austempered at various temperatures at $260^{\circ}C$, $320^{\circ}C$ and $380^{\circ}C$ for 30 min in a salt bath. The mechanical properties were measured by using a tensile test. A detailed study of the microstructure of this steel after heat treatment was carried out by means of electron back scattering diffraction (EBSD) technic. In this study, a new low alloy steel with high strength (780~1,050MPa) and exceptionally high ductility (20~40%) was obtained.

• 한국산학기술학회논문지
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• 제14권11호
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• pp.5377-5384
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• 2013

본 논문은 심층수용 열교환기 재질로 티타늄, 알루미늄, 스테인리스, 구리와 알루미늄을 코팅하여 재질의 특성 및 부식이 미치는 영향을 조사하기 위하여 이중관 열교환 실험장치를 활용하였다. 열교환기 재질은 티타늄, 스테인레스, 구리, 알루미늄, 카본 코팅된 알루미늄 등 6종이 비부식관과 부식관에 대하여 해석과 실험이 수행되었다. 해석은 EES 프로그램을 사용하였다. 부식의 영향을 살펴보기 위하여 부식 제조장치를 제작하고, 3.5%의 염수를 $70^{\circ}C$의 온도로 약 6주간 담가서 가속부식을 실시하였다. 부식된 관으로 이중관 열교환기의 성능실험을 실시하여 비부식관과 비교하였다. 실험결과로부터 티타늄을 대체용으로 알루미늄 코팅관(카본 블랙 $150{\mu}m$)의 가능성을 확인하였다.

• 동아시아식생활학회지
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• 제23권2호
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• pp.203-210
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• 2013

In this study, cod bone were used as the main ingredient of a stock that can be eaten with Korean dried noodles. The stock was produced with heating for 30, 40, 50, 60, or 70 minutes using high-pressure extraction methods. Moisture content, chromaticity, pH, sugar content, salinity, mineral contents, quantitative analysis, and overall acceptance were studied to determine the optimal heating time. In our result, S1 the showed highest water contents 98.10%, while S5 showed the lowest moisture content (97.47%). There were no significant difference in pH between samples, while salinity and sugar content increased with increases in heating time. In terms of mineral contents, sodium and potassium showed proportional difference with increases in heating time, however, magnesium, calcium, and iron did not change. The results from a quantitative analysis test showed that transparency, fishy smell, delicate flavor, savory flavor, salt taste, and umami taste became stronger with increases in heating time increase. From the above results, the overall taste of the stock increases with increases in high-pressure heating time. Specifically, S4 high-pressure heating scored the highest on appearance, flavor, taste, after-taste, and overall acceptance. Thus, 60 minutes of high-pressure heating time is most desirable when producing stock with cod bones as a main ingredient.

• Korean Chemical Engineering Research
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• 제46권4호
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• pp.769-776
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• 2008

키랄성 말단기의 에폭사이드는 키랄중간체나 여러 출발물질로서 다양하게 이용되기 때문에 그 선택적인 합성법은 매우 유용하다. 본 연구에서는 염화코발트(II), 염화철(III) 및 질산아연(II)을 각각 함유한 키랄 코발트 살렌 촉매를 새로이 합성하고 그 특성을 평가하였다. 질량분석과 EXAF분석을 통하여 형성된 촉매 착체의 구조를 평가하였다. 합성한 촉매는 방향족 에폭사이드인 스타이렌 옥사이드와 페닐글리시딜 에테르의 속도차에 의한 비대칭 가수분해적 고리열림반응과 글리시틸부틸레이트의 합성반응에 적용하여 그 활성과 선택성을 조사하였다. 합성이 용이한 전이금속염함유 살렌착체 촉매는 물을 친핵체로 하는 라세믹 에폭사이드의 고리 열림을 통하여 99%ee 이상을 나타낼 정도의 매우 높은 광학선택성을 보였으며, 적은 양의 첨가로도 높은 활성을 보였다. 본 연구에서 적용한 촉매씨스템은 키랄 에폭사이드 및 1,2-디올 중간체의 제조에 매우 효과적이었다.

• Nuclear Engineering and Technology
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• 제48권1호
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• pp.16-25
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• 2016

In severe loss of coolant accidents (LOCA), similar to those experienced at Fukushima Daiichi and Three Mile Island Unit 1, the zirconiumalloy fuel claddingmaterials are rapidlyheateddue to nuclear decay heating and rapid exothermic oxidation of zirconium with steam. This heating causes the cladding to rapidly react with steam, lose strength, burst or collapse, and generate large quantities of hydrogen gas. Although maintaining core cooling remains the highest priority in accident management, an accident tolerant fuel (ATF) design may extend coping and recovery time for operators to restore emergency power, and cooling, and achieve safe shutdown. An ATF is required to possess high resistance to steam oxidation to reduce hydrogen generation and sufficient mechanical strength to maintain fuel rod integrity and core coolability. The initiative undertaken by Electric Power Research Institute (EPRI) is to demonstrate the feasibility of developing an ATF cladding with capability to maintain its integrity in $1,200-1,500^{\circ}C$ steam for at least 24 hours. This ATF cladding utilizes thin-walled Mo-alloys coated with oxidation-resistant surface layers. The basic design consists of a thin-walled Mo alloy structural tube with a metallurgically bonded, oxidation-resistant outer layer. Two options are being investigated: a commercially available iron, chromium, and aluminum alloy with excellent high temperature oxidation resistance, and a Zr alloy with demonstratedcorrosionresistance.Asthese composite claddings will incorporate either no Zr, or thin Zr outer layers, hydrogen generation under severe LOCA conditions will be greatly reduced. Key technical challenges and uncertainties specific to Moalloy fuel cladding include: economic core design, industrial scale fabricability, radiation embrittlement, and corrosion and oxidation resistance during normal operation, transients, and severe accidents. Progress in each aspect has been made and key results are discussed in this document. In addition to assisting plants in meeting Light Water Reactor (LWR) challenges, accident-tolerant Mo-based cladding technologies are expected to be applicable for use in high-temperature helium and molten salt reactor designs, as well as nonnuclear high temperature applications.

• 한국지형학회지
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• 제20권3호
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• pp.79-94
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• 2013

삼한시대 영남지방의 소국 가운데 하나였던 경주는 한반도의 남동쪽에 치우쳐 있음에도 불구하고 천년 동안 고대국가의 수도로 유지되고 성장하였다. 전 세계에서 유래가 드문 이와 같은 사례는 경주 지역에 살았던 사람들의 정치적 능력과 지혜 등 다양한 요인에 기인하지만, 이들이 살았던 지역의 자연환경도 크게 영향을 미쳤을 것이다. 경주에서 고대국가의 성립과 발전을 소백산맥과 태백산맥, 단층선과 선상지의 분포, 해안 분포 특성과 관계지워 논의하였다. 지형 특성은 경주 지역에 경작지 확보를 통한 풍부한 곡물의 공급, 높은 인구부양력과 거대 도시의 입지를 가능하게 하였다. 경주는 동해안에서 결절율이 가장 높은 위치를 점하여 소금과 철제품의 생산과 유통을 통해 부를 축적하고, 우월한 군사적 입지로 주변국과의 경쟁에 유리한 위치를 차지했다. 경주는 지형특성으로 인한 입지적 장점으로 고대국가의 중심지가 되었다.

• Journal of Magnetics
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• 제5권1호
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• pp.16-18
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• 2000

The garnets $Nd_{1-x}Bi_xY_2Fe_5O_{12}$ ($\chi$=0.0, 0.25, 0.5, 0.75 and 1.0) have been studied by x-rays, electron microscopy, ferromagnetic resonance, vibrating sample magnetometer and Mossbauer spectroscopy, Ultra-fine polycrystalline cubic samples have been prepared by a melt-salt routed sol-gel method. The Mossbauer spectra consist of two sets of six-line patterns corresponding to $Fe^{3+}$ at the tetrahedral 24(d) and octahedral 16(a) sites. Magnetic hyperfine fields of $Nd_{0.5}Bi_{0.5}Y_2Fe_5O_{12}$ at 12 K are found to be 548 kOe (octahedral site) and 475 kOe (tetrahedral site), respectively, It is found that Debye temperatures for the tetrahedral and octahedral sites of $Nd_{0.75}Bi_{0.25}Y_2Fe_5O_{12}$ are $\theta_{tet}=436$ K and $\theta_{oct}=285$ K, respectively, The iron ions at both sites are highly covalent ferric. The Nel temperature decreases linearly with Bi concentration, from 630 K fur $\chi$=0.0 to 600 K for $\chi$=1.0, suggesting that the superexchange interaction for the Nd-O-Fe link is stronger than that for the Bi-O-Fe link. As a consequence, the coercivity of $Nd_{1-x}Bi_xY_2Fe_5O_{12}$ drastically decreases and the magnetization remains almost constant as x increases.