• 한국구조물진단유지관리공학회 논문집
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• 제27권6호
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• pp.138-143
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• 2023

이 연구에서는 탄산칼슘 형성 박테리아의 내생포자를 접종한 알지네이트 겔과 포자현탁액 형태의 균열치유제를 모르타르에 첨가하여 균열치유성능을 비교, 분석함으로써 균열치유제 제조방법별 균열치유성능을 분석하였다. 또한 박스형 암거 형태의 실 구조물에 적용하여 실험실 환경뿐만 아니라 개발된 균열치유제가 실제 현장에 적용될 수 있는 환경을 조성하여 실구조물 스케일에서 균열치유성능을 검증하고자 하였다. 건조 방식을 달리한 두 가지 형태의 알지네이트 겔로 구성된 균열치유제를 분석한 결과, 건열건조 방식의 균열치유제는 균열치유 성능을 나타내었으나, 동결건조 방식의 경우 얼음 결정에 의해 다수의 포자가 사멸되어 균열치유성능을 잃는 것으로 나타났다. 실스케일 구조물의 균열부에서 추출된 균열치유 추정물질의 SEM 사진과 XRD 패턴 분석 결과 균열치유제에 적용된 균열치유 미생물이 생성한 탄산칼슘 결정 중 하나인 calcite인 것으로 나타났으며, 미생물에 의한 균열치유메커니즘이 실구조물에서 구현될 수 있음을 확인하였다.

• 한국광물학회지
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• 제13권2호
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• pp.84-95
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• 2000

Tremolite crystals from the Dongyang talc deposit were studied using high-resolution transmission electron microscopy (HRTEM) to characterize the tremolite-to-talc reaction. [001] HRTEM images of tremolite show intergrowths of wide-chain pyriboles and talc; talc is the primary alteration product of tremolite, and triple-chain structures occur sparsely. The boundaries between tremolite and talc are commonly well defined by (010) and (100) interfaces. (001) talc layers are parallel to (100) of tremolite, and the interfaces between tremolite and talc appear to be coherent in HRTEM images, indicating that most talc laters formed directly from tremolite by a gydration reaction. However, some talc formed along (110) of tremolite, and talc layers are not extended from (010) of tremolite, suggesting that part of talc in the deposit was produced through a dissolution-precipitation mechanism. Carbonate minerals are also associated with tremolite and talc. Common replacement of dolomite by calcite indicates that the tremolite-to-talc reaction results in remnant Ca, which was eventually consumed to replace dolomite to form clacite. Some Mg Produced by dolomite during reaction to calcite was apparently utilized to form talc, because talc formation from tremolite requires extra Mg. Although talc could be formend directly from dolomite, extensive alteration of tremolite to talc suggests that part of talc of the deposit was produced from tremolite that was formed by dolomite reaction during an early stage metamorphism.

• Journal of Microbiology and Biotechnology
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• 제20권4호
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• pp.782-788
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• 2010

Microbiological calcium carbonate precipitation (MCP) has been investigated for its ability to improve the compressive strength of mortar. However, very few studies have been conducted on the use of calcite-forming bacteria (CFB) to improve compressive strength. In this study, we discovered new bacterial genera that are capable of improving the compressive strength of mortar. We isolated 4 CFB from 7 environmental concrete structures. Using sequence analysis of the 16S rRNA genes, the CFB could be partially identified as Sporosarcina soli KNUC401, Bacillus massiliensis KNUC402, Arthrobacter crystallopoietes KNUC403, and Lysinibacillus fusiformis KNUC404. Crystal aggregates were apparent in the bacterial colonies grown on an agar medium. Stereomicroscopy, scanning electron microscopy, and X-ray diffraction analyses illustrated both the crystal growth and the crystalline structure of the $CaCO_3$ crystals. We used the isolates to improve the compressive strength of cement-sand mortar cubes and found that KNUC403 offered the best improvement in compressive strength.

• 한국재료학회지
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• 제8권12호
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• pp.1133-1137
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• 1998

MCFC(Molten Carbonate Fuel Cell) 작동온도인 $650^{\circ}C$에서 Ni 음극의 Creep 및 소결에 대한 저항성을 개선시키고자 Ni-W(WC) 복합재료를 기계적 합금법으로 제조하였다. 기계적 합금화한 분말의 XRD분석결과 밀링시간이 증가함에 따라 재료의 규칙적인 결정이 파괴되어 비정질화 되어가는 경향을 보였다. 소결은 $1280^{\circ}C$의 수소분위기에서 10시간 행하였다 소결된 시편의 dot-mapping 및 TEM 분석결과 Ni-W 계면에서의 2차상 관찰되지 않았으나 $0.1\mu\textrm{m}$ 이하의 W이 Ni 기지내에 미세하고 균일하게 분포되어 있는 것으로 나타났다. 이와같이 미세하고 균일하게 분포되어 있는 W은 고용강화 및 분산강화 효과를 통하여 Ni음극의 기계적 특성을 향상시킬 것으로 기대된다.

• Restorative Dentistry and Endodontics
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• 제20권2호
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• pp.818-826
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• 1995

The present study was undertaken to investigate the crystal growth onto enamel mineral and synthetic hydroxyapatite seeds in media resembling the enamel fluid composition. Effects of fluoride at low concentrations on the precipitation were also examined in a benchtop crystal growth model adopting a miniaturized reaction column. X-ray diffraction and Fourier transform infrared spectroscopy(FTIR), as well as chemical analyses, were employed for characterization of both seed materials before and after experimentation. Remarkable findings were that (1) both biological and synthetic seeds at the same total surface areas yielded rather similar precipitation rates at all levels of fluoride concentration in solution and (2) the precipitation rate was accelerated in a manner depending on fluoride concentrations in media. FTIR differential analysis disclosed that the precipitating phase was characterized as poorly crystallized apatite, which incorporated subtle carbonate. Most of the fluoride ions in soution were readily incorporated into crystals. The overall results support the view that the seeded crystal growth model is of value to gain insight into the mechanism of enamel crystal growth under fluoride regimens.

• 대한소아치과학회지
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• 제23권3호
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• pp.640-658
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• 1996

The purpose of this study was to examine the mechanism of improving acid resistance of Nd-YAG laser irradiated tooth enamel and determine the most effective energy density for improving acid resistance. The bovine tooth enamel were lased with a pulsed Nd-YAG laser. The energy densities of exposed laser beam were varied from 10 to $70\;J/cm^2$. To investigate the degree of improving acid resistance by irradiation, all the samples were submerged to demineralize in 0.5 N $HClO_4$ solution for 1 minute. After 1 minute, 0.05 % $LaCl_3$ was added to the solution for interrupting the demineralization reaction. The amounts of dissolved calcium and phosphate in the solution were measured by using an atomic absorption spectrophotometer and the UV/VIS spectrophotometer, respectively. To examine the mechanism of improving acid resistance, X-ray diffraction analysis, infrared spectroscopy, and scanning electron microscopy were taken. The X-ray diffraction pattern of the samples were obtained in the $10^{\circ}{\sim}80^{\circ}2{\theta}$ range with $Cu-K{\alpha}$ radiation using M18HF(Mac Science Co.) with X-ray diffractometer operating at 40 KV and 300 mA. The infra-red spectra of the ground samples in 300 mg KBr pellets 10 mm diameter were obtained in the $4000cm^{-1}\;to\;400cm^{-1}$ range using JASCO 300E spectrophotometer. The scanning electron microscopy was carried out using JSM6400(JEOL Co.) with $500{\sim}2000$ times magnification. The results were as follow 1. The concentration of calcium dissolved from laser irradiated enamel with $50J/cm^2$ was significantly lesser than that of unlased control group (p<0.05) 2. From the result of the X-ray diffraction analysis, $\beta$-TCP, which increases acid solubility, was identified in lased enamel but the diffraction peaks of (002) and (004) became sharp with increasing energy density of laser irradiation. This means that the crystals in lased samples were grown through the c-axis and subsequently, the acid solubility of enamel decreased. 3. The a-axis parameter was slightly increased by laser irradiation, whereas the c-axis parameter was almost constant except for a little decrease at $50J/cm^2$. 4. In the infra-red spectra of lased enamels, phosphate bands ($600{\sim}500cm^{-1}$), B-carbonate bands (870, $1415{\sim}1455cm^{-1}$), and A-carbonate band ($1545cm^{-1}$) were observed. The amounts of phosphate bands and the B-carbonate bands were reduced, on the other hand, the amount of the A-carbonate band was increased by increase the energy density. 5. The SEM experiments reveal that the surface melting and recrystallization were appeared at $30J/cm^2$ and the cracks were observed at $70J/cm^2$. From above results, It may be suggested that the most effective energy density for improving acid resistance of tooth enamel with the irradiation of Nd-YAG laser was $50J/cm^2$. The mechanism of improving acid resistance were reduction of permeability due to surface melting and recrystallization of lased enamel and reduction of acid solubility of enamel due to decrease of carbonate content and growth of crystal.

• 한국항해항만학회지
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• 제46권4호
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• pp.297-302
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• 2022

탄산칼슘과 염산 수용액에 폴리프로필렌 섬유를 침지시켜 표면에 염화칼슘 결정을 생성시킴으로써 발열 흡착포를 제작하였다. 발열 흡착포를 유출 기름으로 인해 유막이 형성된 해수면에 적용하면 염화칼슘 결정이 주변의 수분을 흡수하여 이온화되면서 용해열을 방출한다. 염화칼슘의 용해열을 유동점 이하의 저온에서 응고된 저유황 중질유를 액화시켜 흡유 가능한 상태로 전환시킨다. 발열 흡착포의 제작을 위해 폴리프로필렌 표면에 염화칼슘 결정을 생성시키기 위한 탄산칼슘과 염산의 최적 몰농도는 각각 0.25 M과 0.5 M이다. 저유황 중질유 발열 흡착포의 흡유능은 해수 온도에 따라 다르지만, 우리나라 인근 해역의 동절기 평균 수온인 10℃에서 4.5-7.08 g/g으로 매우 우수하였다. 염화칼슘 발열 흡착포를 사용하면 동절기 선박사고로 인하여 해양에 유출된 저유황 중질유를 효과적으로 흡유하여 제거할 수 있다.

• Korean Chemical Engineering Research
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• 제48권3호
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• pp.350-354
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• 2010

자연계에는 유/무기 복합막 형성시 크기와 배열이 정교하게 제어되면서 여러 무기물 결정들이 성장한다. 이와 같은 자연계의 유/무기 복합막을 인공적으로 재현하기 위한 시도가 다각적으로 이루어지고 있다. 유/무기 계면에서 생체모방 결정화의 대표적인 물질 중의 하나가 바로 탄산칼슘 결정이다. 탄산칼슘은 생체 내의 골격을 이루는 주성분이고 성장방법이 비교적 간단하여 많은 연구가 수행되어 왔다. 분자수준에서의 우수한 정돈 상태들을 지니고 있는 폴리다이아세틸렌(polydiacetylene: PDA)은 무기결정성장에 관하여 효과적인 template를 제공할 수 있다. 본 실험에서는 폴리다이아세틸렌의 패턴들을 고체기판에 동시에 증착시키기 위하여, 신규로 고안한 mini arrayer의 air/water의 계면을 이용하여 소수성 유리기판위에 PDA를 전이시켰다. 이 방법을 이용한 결정화 과정의 제어는 생체유도결정화의 매커니즘을 이해하는데 기여할 수 있을 것이다.

• 한국환경과학회지
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• 제17권9호
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• pp.981-992
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• 2008

This study examined how to produce new methods of copper (II) sulfate crystallization by using a small-scale chemistry tool such as small-scale reaction surface and petri dish. The making of copper(II) sulfate is included in the 5th grade elementary science textbooks. Various copper(II) compounds were reacted with a 2 M sulfuric acid solution. The result of this study is as follows: Seven small amounts of copper(II) compounds were reacted with a few drops of 2 M sulfuric acid solution at room temperature to make a copper(II) sulfate crystal of triclinic shape. Using the petri dish method, a copper(II) sulfate crystal could be identified within one hour of reacting copper(II) hydroxide, copper(II) carbonate, copper(II) nitrate, copper(II) perchlorate, cupric(II) formate from a few drops of 2 M sulfuric acid solution at room temperature. When using the lap top method for copper(II) perchlorate, cupric formate, a proper crystal could be identified within one hour as well. SSC methods were used for the first time to make a copper sulfate crystal via chemical reaction. We can make a copper(II) sulfate crystal using a simple method which is easier, safer and saves time in class. And since a small quantity of chemicals are being used in SSC chemical methods, waste is greatly reduced. This lessens the amount of environmental problems caused by the experiment. This can be helpful in preserving nature. In addition the cost of chemical and laboratory equipment is greatly reduced because it uses material that we find in our daily lives. There will be continued study of small-scale methods such as improvement of new programs, study and training of teachers, and securing SSC tools. I would like to suggest such as SSC methods are applicable in elementary School Science. I would like it to become a wide spread program.

• 대한한방내과학회지
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• 제21권1호
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• pp.181-184
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• 2000

Dizziness is one of common diseases clinically, it is defined as a hallucination or an illusion of motion that causes sensation disorder of circumstance, and described as circulatory. rotatory leaning. shaking sensation. In particular, benign paroximal positional vertigo(BPPV) is one of peripheral vertigo, it causes dizziness due to debris which has collected within a part of the inner ear. Chemically, debris are small crystals of calcium carbonate. They are derived from structures in the ear called 'otoliths' that have been damaged by head injury, infection, or other disorder of the inner ear, or degenerated because of advanced age. The symptoms of BPPV include dizziness or vertigo, lightheadedness, imbalance, and nausea, Activities which bring on symptoms will vary in each person, but symptom are almost always precipitated by a position change of the head or body. As for treatment of vertigo, it is differentiated as excess in the upper and deficiency in the lower(上實下虛) and treated in oriental medicine and are used to stability. antihistaminics . anticolinergics . vestibule control drug of GABA system in western medicine. Moreover, Dix-hallpike maneuver is applicated in diagnosis and treatment of BPPV patients. A case of dizziness patient suggested benign paroximal positional vertigo who is diagnosed as weakly dizziness(虛暈)showed prominent improvement by Jaeumkunbitang-gamibang(滋陰建脾湯) and Dix-hallpike maneuver.