• Journal of the Korean Chemical Society
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• v.43 no.5
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• pp.578-588
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• 1999

The purpose of this study is to develope the more effective chemistry teaching strategy through analyzing the demanded cognitive levels of contents in high school chemistry I textbooks and the cognitive levels of students who learn these textbooks. For this purpose, the levets of cognitive development stages of 821 second grade students of high schools in Seoul City were anaIyzed using the GALT short version test. The demanded cognitive levels of understanding the contents of chemistry I textbooks in high school were analyzed using the curriculum analysis taxonomy developed by CSMS (Concept in Secondaly Mathematics and Science) program of the Great Britain. The resuIts showed that the proportion of students in the concrete operational stage, the transition stage, and the formal operational stage was l0.7%, 43.0% and 46.3%, respectively. The demanded levels of textbook contents were mostly the early formal operational stages. The concepts demanded the level of the late formal operational stage were 'atomic and molecular weight', 'stoichiometry of chemical reaction', and 'periodic properties of elements'. The results will be helpful for teachers in knowing what concepts are difficult for students to understand and in planning strategies for teaching those concepts. To demonstrate the application of the results obtained in this study, an example of developing teaching strategy which includes the adjustment of cognitive level of contents was shown.

• 한국석유지질학회:학술대회논문집
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• 2005.09a
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• pp.94-100
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• 2005

동해 울릉분지 북서부해역에서 채취한 코어퇴적물을 이용하여 울릉분지의 제4기 후기 층서와 퇴적환경을 연구하였다. 이를 위하여 테프라층서, 탄소연대측정, 퇴적상, 퇴적물의 암질, 퇴적물과 공극수의 원소성분 등을 분석하였다. 퇴적상을 기준으로 코어퇴적물은 Unit 1, Unit II 및 Unit III으로 나누어지며, Unit의 경계부근에서는 주로 화산력으로 구성된 2매의 향암질 또는 조면암질 테프라층과 주로 화산재로 구성된 1매의 유문암질 테프라층이 협재되어 나타난다. 이들 테프라층에는 울릉도에서 기원한 울릉-오키층(Unit I/II 경계, 약 8.1 cal. kyr BC)과 울릉-야마토층(약 30.7 cal. kyr BC), 일본에서 기원한 아이라-탄자와층(Unit I/II경계, 약 22.8 cal. kyr BC)이 있다. Unit II의 중간부근에서 발견되는 DLM(Dark Laminated Mud) 층에는 망간보다는 철이 상대적으로 풍부하고, 철은 주로 구상집적체의 황화철로 발견되는데, 이들 광물은 정체환경 동안 물의 순환이 약화된 시기에 무산소환경에서 형성되었다. 퇴적물 내 유기물은 해양성 기원으로, 열적 성숙단계가 대부분 미성숙단계에 놓여 있다. Termination I 전에 급격하게 총유기탄소 (TOC)의 함량이 증가함을 보여주는데, 이는 빙기에서 간빙기로 변하는 시기에 해수면 변동과 관련이 있는 것으로 보인다. 공극수와 공기층 가스의 분석에 의하면, 황산염($SO_4^{2-}$) 농도는 매몰심도와 함께 증가하고, 반대로 공기층 가스의 주성분인 메탄($CH_4$)의 농도는 감소한다. 이는 미생물학적인 활동과 관련된 황산염 환원작용이 코어 상부에서 일어났으며, 점차 메탄생성단계 (methanogenesis)로 전이가 일어났음을 의미한다.측해본 결과 침몰선체의 강도는 초기강도에 비해 약 2/5정도 감소하였음을 알 수 있었다.할 수 있었다. 이 연구 사례를 통하여 3차원 GPR 탐사 또한 국부적인 이상대의 규명뿐만 아니라 광역적인 고고학 조사에도 다른 물리탐사와 마찬가지로 쉽게 활용될 수 있다는 결론을 얻을 수 있었다. 3차원 GPR 탐사가 향후 국내의 문화재 조사에 표준화된 탐사과정 중의 하나로써 적극 활용되길 기대한다.larity가 높은 oil에서는 약 $70 {\~} 90\%$의 phenoxyethanol이 유상에 존재하였다. 또한, 미생물에 대한 항균력도 phenoxyethanol이 수상에 많이 존재할수록 증가하는 경향을 나타내었다. 따라서, 제형 내 oil tomposition을 변화시킴으로써 phenoxyethanol의 사용량을 줄일 수 있을 뿐만 아니라, 피부 투과를 감소시켜 보다 피부 자극이 적은 저자극 방부시스템 개발이 가능하리라 보여 진다. 첨가하여 제조한 curd yoghurt는 저장성과 관능적인 면에서 우수한 상품적 가치가 인정되는 새로운 기능성 신제품의 개발에 기여할 수 있을 것으로 사료되었다. 여자의 경우 0.8이상이 되어서 심혈관계 질환의 위험 범위에 속하는 수준이었다. 삼두근의 두겹 두께는 남녀 각각 $20.2\pm8.58cm,\;22.2\pm4.40mm$으로 남녀간에 유의한 차이는 없었다. 조사대상자의 식습관 상태는 전체 대상자의 $84.4\%$가 대부분이 하루 세끼 식사를 규칙적으로 하고 있었으며 식사속도는 허겁지겁 빨리 섭취하는 경우가 남자는 $31.0\%$, 여자는 $21.4\%$로 나타났고 이들을 제외한 나머지 사람들은 보통 속도 혹은 충분한 시간을 가지고 식사를 하였다. 평소 식사량은 조금 적게

• Korean Journal of Materials Research
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• v.11 no.5
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• pp.405-412
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• 2001

Corrosion tests were carried out in $360^{\circ}C$ water and $360^{\circ}C$ 70ppm LiOH solution to investigate the corrosion behavior of new zirconium alloys (Zr-0.4Nb-0.8Sn-xFeCrMn, Zr-0.2Nb-1.1Sn-xFeCrMn, Zr-1.0Nb-xFeCu). Microstructures of tested alloys were analyzed by optical microscope and TEM. The cross-sectional surface and crystalline structure of the oxide layer were analyzed by SEM and XRD. From the results of corrosion test, all the alloys showed higher corrosion rates in $360^{\circ}C$ 70ppm LiOH aqueous solution thats in $360^{\circ}C$ water. Especially, high Nb-containing alloy exhibited the acceleration of corrosion rate in LiOH solution. The low Nb- and Sn-added alloys showed better corrosion resistance than the Sn- free high Nb alloy. from the effect of final annealing on the corrosion, it was observed that the partially recrystallized alloys showed better corrosion resistance than fully recrystallized alloys. This would be related to the size and distribution of the second phase particles.

• The Journal of the Petrological Society of Korea
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• v.7 no.1
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• pp.27-36
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• 1998

The volcanic piles in the northern Yucheon Minor Basin area are the Hagbong basaltic rocks, the Chaeyaksan basaltic rocks, the Jusasan andesitic rocks, the Unmunsa rhyolitic rocks, and the Tertiary voicanics. Stratigraphically, from the lowermost, (1) the Hagbong basaltic rocks are composed mainly of basaltic tuff with two olivine basalt flows intercalated, (2) the Chaeyagsan basaltic rocks are predominantly in tuffs and agglomerate with 3 basaltic flow interlayers, (3) the Jusasan andesitic rocks consist of thick piles of alternated sequences of 4 andesite flows and 5 andesitic tuffs and tuffaceous sediments and (4) the Unmunsa rhyolitic rocks which embed some rhyolite and obsidian are dominant in tuffs such as ash flow and crystal welded tuff. These volcanics reveal distinguishable characteristics in petrochemistry. In discriminating by major elements, the Hagbong and the Chaeyagsan basaltic rocks are alkaline, whereas the latter is also spilitic. In comparison, the volcanic rocks of the Jusasan andesitic rocks and the Tertiary sequences are characteristically calc-alkaline although their distribution is spatially separated. On the other hand, the variations in immobile trace elements indicate that the Hagbong basaltic rocks range from alkaline to calc-alkaline and from WPB/VAB transition to VAB, whereas the Chaeyagsan basaltic rocks are calc-alkaline WPB/VAB transition type and the two others calc-alkaline VAB. In order to show such a variety in their rock series of the volcanic rocks, the environment during their magma generation, magma rising, and post-eruption alteration could be positively considered.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 1998.05a
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• pp.21-21
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• 1998

새로운 에너지원으로 각광받고 있는 연료전지는 우주선 동력윈으로서의 이용이래, 보다 실용적인 발전 시스템을 목적으로 많은 연구개발이 시도되고 있다. 이러한 연료전지는 사용하는 전해질의 특성으로 인하여 저온형($<300^{\circ}C$) 과 고온형($500^{\circ}C<$)으로 구분된 수 있는데, 저온형 연료전지의 경우는 전극반응 특성상 귀금속 촉매가 필요한 데 비해, 고온형 연료전지는 이러한 귀금속 촉매가 필요없다는 점등에서 다양한 장점을 가지게 된다. 즉, 저온형에 비해 다양한 연료가 가능하고, 대형화에 유리함며, 고온 페열을 이용할 수 있는 점 등을 들 수 있다. 용융탄산염형 연료전지(MFCFC)는 이러한 고온형 연료진지의 장점을 배경으로 현재 대규모의 개발이 진행되고 있다. 그러나 여기에 주로 사용되는 Li-K, Li-Na와 같은 용융탄신엽은 고부식성 전해질로서 대부분의 금속이 산화물을 형성하는 것으로 알려져 있다. MCFC의 분리판은 셀간을 전기적으로 이어주는 역할, 가스의 유로제공 및 가스 Sealing의 역할을 담당하는 부분으로서, 분리판의 부식은 이러한 특성의 저하 및 전해질의 소모를 유발시켜 MCFC의 내구성에 커다란 영향 을 미치는 요인으로 생각되고 있다. 이러한 배경으로부터 Uchida 그룹은 MCFC의 분라판 재료 의 부식거동을 계동적으로 검토하였다. 먼저 Fe에 Ni 과 Cr을 첨가한 재료를 산화성가스 분위기하에서 $(Li+K)CO_3$에 대하여 검토한 결과, Ni과 Cr 둘다 20wt%이상 첨가시, 내식성융 가지는 결 과를 보고하였다2) 이 경우 보호피막으로서 NiO 와 $LiCrO_2$가 작용하는데, $LiCrO_2$가 용융탄산염 중에서 보다 안정한 것으로 부터, Cr의 첨가가 내식성에 기여하는 것으로 판단하였다. 다음 단계 로서 Fe/Cr재료에 용-융탄산염 중에서 안정한 산화물을 형성하는 Al의 첨가효과를 검토하였다. Al의 첨가는 더욱 내식성을 향상시키는 것이 발견되었고, 약 4wt%의 첨가로 충분한 내식성을 가지 는 것을 보고 하였다. 그러나 이러한 안정한 산화물에 의한 내식성 향상은 전기진도도의 희생을 바탕으로 한 것으로서, 다읍 단계로서 Ti산화물의 반도체적인 특성을 이용하고자 제 4의 원소로서 Ti첨가를 시도하였다. 그러나 Fe/Cr/AVTi재료가 뛰어난 내식성을 가지는 것은 관찰되었으나, 전도도 향상에는 기여하지 못하는 것이 보고되었다. 현재 MCFC는 실용화를 위한 고성능화의 하나로서 가압하에서의 운전을 시도하고 있다. 이 러한 가압하에서의 운전은 기전력의 향상 및 전극반응의 촉진 등으로 출력의 향상을 가져오나. 현재 문제로 되고 있는 Cathode극인 NiO의 용해/석출 현상을 가속화하는 결과를 초래해, 이에대 한 대책으로서 Li-K보다 NiO의 용해가 적은 Li-Na탄산염으로의 전환이 진행되고 있다. 이러한 배경으로부터 Uchida그룹에서 개발한 FeiCr/AVTi재료와 현재 분리판 재료로 사용증인 SUS 310, S SUS 316재료에 대해. 산화성 분위기의 5기압까지의 가압하에서, Li-K, Li-Na탄산염에 대하여 부 식거동을 검토한 결과, 가압하에서 내식성이 향상되는 것이 발견되었다. 이유로서는 가압하에서 용융탄산엽의 증가된 산화력으로 보다 치밀한 내식성 산화물 피막이 형성되기 때문으로 생각되고 있다. 또한 Li-K, Li-Na탄산염에서의 부식의 정도에는 차이가 거의 없었으나, SUS 316의 경우 탄산염에 젖은 부분에서 내식성 피막이 형성되지 않는 이상부식현상이 관찰되었다. 재료간의 내식성 정도에서는 Fe/Cr/Al/Ti이 가장 내식성이 뛰어났으며, SUS 310 또한 뛰어난 내식성을 보였다.

• Applied Biological Chemistry
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• v.16 no.1
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• pp.41-48
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• 1973

1. Through out the entire stage of growth, the amount of nutrients, number of tillers and of spikes increased in the Simagcalin treated plot as compared with the control. The treated plot showed healthul growth at the later growing stage. On the other hand, management of irrigation water resulted in raised the grain straw ratio and retarded the culm height about 10%. 2. Application of Simagcalin greatly increased the content of phosphorus and magnesium at the harvesting time. The culm and sheath analyses are recommendable for the determination of magnesium deficiency. 3. The controled irrigation would effect root activity as the main factor, and Simagcalin might act as a secondary factor. 4. While the application of phosphorus may not affect the yield components, The basic elements in Simagcalin may enhance the uptake of nutrients under heavy application of nitrogn.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.5 no.4
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• pp.339-350
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• 2007

Status on the spent nuclear fuel management policy and R&D plan of the major countries is surveyed. Also the prospect of the future R&D plan is suggested. Recently so-called fuel cycle nations, which have the reprocess policy of the spent fuel, announced new spent fuel management policy based on the advanced fuel cycle technology. The policy is focused to transmute highly radioactive material and material having a very long half-life, and to recycle the Pu and U contained in the spent fuel. In this way the radio-foxily of the spent fuel as well as the amount of the high level waste to be eventually disposed can greatly be reduced. Most of countries selected the wet process as a primary option for the treatment of the spent fuel since the advanced wet process, which is based on the existing PUREX process, looks more feasible as compared with the dry process. The wet process, however, is much more sensitive in terms of proliferation-resistance compared with the dry process. The pure Pu can easily be obtained by simply modifying the process. On the other hand the pure Pu can not be extracted in the dry process based on the high temperature molten salt process such as a pyroprocess. Even though the pyroprocess technology is very premature, it has a great merit. Thus it is necessary for Korea to have a long term strategy for pursuing a spent fuel treatment technology with a proliferation resistance and a great merit for the GEN-IV fuel cycles. Pyroprocess is one of the best candidates to satisfy these purposes.

• Korean Journal of Soil Science and Fertilizer
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• v.38 no.5
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• pp.274-280
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• 2005

Enormous amount of oyster-shell waste has been illegally disposed at oyster farm sites along the southern coast of Korea and then made a serious problem in environmental side. To increase the consumption of oyster shell meal as a soil amendment, the effects of oyster shell meal on soil properties and spring Chinese cabbage productivity were evaluated in silt loam soil to which 0, 4, 8, 12 and $16Mg\;ha^{-1}$ of oyster-shell meal fertilizer were added. Hydrated lime treatment ($2Mg\;ha^{-1}$) was selected as a control. Oyster-shell meal fertilizer, which made by a simple crushing and has high alkalinity as a calcium materials, had significant effects on neutralizing acid soil and on supplying calcium element. Spring Chinese cabbage yields increased with shell meal application. Plant uptakes of macro-nutrients such as P and C, and micro-nutrient such as B were significantly increased by oyster-shell meal application and then contributed to promote Chinese cabbage growth. The highest yield was achieved following the addition of $8Mg\;ha^{-1}$ shell meal application, and the same yield with that in lime treatment was at the $4Mg\;ha^{-1}$. Oyster-shell meal had more substantial effect on suppling calcium and on improving soil pH than that of lime. In conclusion, oyster shell meal fertilizer could be a good supplement to other inorganic soil amendments to improve nutrient balances in upland soils.

• KSBB Journal
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• v.22 no.5
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• pp.288-296
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• 2007

Monascus pilosus (KCCM 60160) in submerged culture was optimized based on culture medium and fermentation conditions. Monacolin-K (Iovastatin), one of the cholesterol lowing-agent which was produced by Monascus pilosus may maintain a healthy lipid level by inhibiting the biosynthesis of cholesterol. Plackett-Burman design and response surface method were employed to study the culture medium for the desirable monacolin-K production. As a result of experimental designs, optimized production medium components and concentrations (g/L) were determined on soluble starch 96, malt extract 44.5, beef extract 30.23, yeast extract 15, $(NH_4)_2SO_4$ 4.03, $Na_2HPO_4{\cdot}12H_2O$ 0.5, L-Histidine 3.0, $KHSO_4$ 1.0, respectively. Monacolin-K production was improved about 3 times in comparison with shake flask fermentation of the basic production medium. The effect of agitation speed (300, 350, 400 and 450 rpm) on the monacolin-K production were also observed in a batch fermenter. Maximum monacolin-K production with the basic production medium was 68 mg/L when agitation speed was 500 rpm. And it was found that all spherical pellets (average diameter of $1.0{\sim}1.5mm$) were dominant during fermentation. Based on the results, the maximum production of 185 mg/L of monacolin-K with the optimized production medium was obtained at pH (controlled) 6.5, agitation rate 400 rpm, aeration rate 1 vvm, and inoculum size 3%.

• Applied Biological Chemistry
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• v.22 no.4
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• pp.198-209
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• 1979

L-Tyrosine, 2-chloro-L-tyrosine, 2-bromo-L-tyrosine, and 2-iodo-L-tyrosine were synthesized by ${\beta}-tyrosinase$ obtained from cells of Escherichia intermedia A-21, through the reversal of the ${\alpha},{\beta}-elimination$ reaction, and their molecular structures were analyzed by element analysis, NMR spectroscopy, mass spectrometry and IR spectroscopy. Rates of synthesis and hydrolysis of halogenated tyrosines by ${\beta}-tyrosinase$, inhibition of the enzyme activity by halogenated phenols, and effects of addition of m-bromophenol on the synthesis of 2-bromotyrosine were determined. The results obtained were as follows: 1) In the synthesis of halogenated tyrosines, the yield of 2-chlorotyrosine from m-chlorophenol were approximately 15 per cent, that of 2-bromotyrosine from m-bromophenol 13.8 per cent, and that of 2-iodotyrosine from m-iodophenol 9.8 per cent. 2) Rate of synthesis of halogenated tyrosines by ${\beta}-tyrosinase$ was slower than that of tyrosine and the rates were decreased in the order of chlorine, bromine and iodine, that is, by increasing the atomic radius. Relative rate of 2-chlorotyrosine synthesis was determined to be 28.2, that of 2-bromotyrosine to be 8.13, and that of 2-iodotyrosine to be 0.98, respectively, against 100 of tyrosine. However 3-iodotyrosine was not synthesized by the enzyme. 3) The relative rate of 2-chlorotyrosine hydrolysis by ${\beta}-tyrosinase$ was 70.7, that of 2-bromotyrosine was 39.0, and that of 2-iodotyrosine was 12.6 against 100 of tyrosine, respectively. The rate of hydrolysis appeared to be decreased in the order of chlorine, bromine and iodine, that is, by increasing the atomic radius or by decreasing the electronegativity. But 3-iodotyrosine was not hydrolyzed by the enzyme. 4) The activity of ${\beta}-tyrosinase$ was inhibited by phenol markedly. Of the halogenated phenols, o-, or m-chlorophenol and o-bromophenol gave marked inhibition on the enzyme action, however inhibition by iodophenol was not strong. Plotting by Lineweaver-Burk method, a mixed-type inhibition by m-chlorophenol was observed and its Ki value was found to be $5.46{\times}10^{-4}M$. 5) During the synthesizing reaction of 2-bromotyrosine by the enzyme, sequential addition of substrate which was m-bromophenol with time intervals and in a small amount resulted in better yield of the product. 6) The halogenated tyrosines which were produced by ${\beta}-tyrosinase$ from pyruvate, ammonia and m-halogenated phenols were analysed to determine their molecular structures by element analysis, NMR spectroscopy, mass spectrometry, and IR spectroscopy. The result indicated that they were 2-chloro-L-tyrosine, 2-bromo-L-tyrosine, and 2-iodo-L-tyrosine, respectively.