• 자원환경지질
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• 제56권3호
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• pp.217-227
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• 2023

결정질 탄산칼슘(CaCO₃)은 방해석(calcite), 아라고나이트(aragonite), 바테라이트(vaterite) 세 동질이상체로 다양한 지질 및 수중 환경에서 흔하게 발생한다. 또한, 탄산칼슘 광물은 기능성 재료로 사용될 수 있어 공학적인 용도로 많은 관심을 받고 있다. 자연계와 공학적인 세팅에서 생성되는 탄산칼슘의 형성 및 그 반응을 이해하고 다양한 생약 및 생의학 물질로 활용하기 위한 탄산칼슘 광물 형성에 대한 실험적 모사 방법(즉, 합성법)에 관한 연구가 활발히 진행되어왔다. 합성법에서 물을 용매로 탄산칼슘 결정 형성을 유도하는 방식(수용액-기반 합성법)은 자연계에서 발생하는 탄산염광물 형성 조건과 유사하므로 지질학 연구에서도 그 의미성이 매우 크다. 본 리뷰 논문에서는 문헌에서 보고되는 수용액-기반 탄산칼슘 합성법을 탄산칼슘 동질이상체 별로 분류한다. 또한, 여러 합성법에서 나타나는 결정의 형상 및 구조적 특성을 동질이상체 별로 분류하고 결정화 메커니즘을 통해 그 특성들을 토론하고자 한다.

• 보존과학연구
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• 통권15호
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• pp.52-58
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• 1994

To protect corrosion of bronze roofing tile for Choson Royal Historic Museum, lead coating on tile was performed by electroplating method with thickness of $35\mum$. Lead coated tile samples were inverstigated what corrosion products were formed with color changes on them by testing Accelerated Weathering. No sulfides were formed on samples contacting with 300ppm sulfur dioxide and any color changes were not found. In Accelerated Weathering test, White hydrocerussite, basic lead carbonate($2PbCO_3Pb(OH)_2$) having protective structure made of compact adhering crystals.

• Korean Chemical Engineering Research
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• 제51권1호
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• pp.151-156
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• 2013

Polydimethylsiloxane (PDMS) 기반의 미세유체 시스템을 이용해 탄산칼슘의 결정화 실험을 수행하였다. 탄산칼슘의 결정화를 위한 다양한 반응방법 중 액체-액체 반응을 위해 염화칼슘 수용액과 탄산나트륨 수용액을 사용하였고 아스파르트산을 첨가하여 탄산칼슘 결정 중 베터라이트와 칼사이트의 생성에 어떤 차이를 보이는지 조사하였다. 그리고 탄산칼슘의 결정화 진행상황에서 결정핵 생성에 유리한 염화칼슘과 탄산나트륨의 비율을 조사하였다. 이를 위해 크리스마스트리 모양의 미세유체 반응기를 사용하여 채널 내부에 염화칼슘과 탄산나트륨의 농도구배를 형성하도록 하였다. 미세유체 결정화기 내부를 광학현미경으로 촬영한 결과, 탄산나트륨과 염화칼슘의 농도비가 2:1일 때 결정핵이 생성됨을 확인하였고 핵 생성 이후의 결정 성장 과정을 촬영하여 결정형태의 변화를 관찰하였다. 아스파르트산의 첨가 시에 결정핵 생성과 성장을 저해하며 전체 결정형태 중 베터라이트의 비율이 높아짐을 보였다.

• 한국수산과학회지
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• 제48권2호
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• pp.168-177
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• 2015

Shell waste from the butter clam Saxidomus purpuratus and littleneck clam Ruditapes philippinarum is a large by-product of shellfish aquaculture, and it is desirable to convert it into value-added products for industrial applications. In this study, calcium carbonate (CaC) polymorphs from butter clam (BCSP) and littleneck clam (LCSP) shell powders and commercial CaC were characterized using Fourier transmission infrared spectroscopy (FT-IR), X-ray diffraction (XRD), and scanning electron microscopy (SEM). The results revealed that the optimal calcination conditions to eliminate organic substances and improve solubility for both BCSP and LCSP were $800^{\circ}C$ for 8 h in an electrical furnace. Calcination improved the white index of the butter clam (BCCP) and littleneck clam (LCCP) calcined powder compared with shell powders. The calcium content in BCCP (51.1%) was higher than that of LCCP (44.9%) or commercial calcium oxide (CaO, 44.7%). The XRD patterns of BCCP and LCCP were similar to that of CaO. Cubic-like crystals of CaC and irregular crystals of BCCP and LCCP were observed by SEM. The FT-IR and XRD analyses revealed the presence of calcite and aragonite in the BCSP and aragonite in the LCSP, whereas the CaC contained calcite. These results indicate that butter and littleneck clam shells are potential biomass resources for calcium carbonate and calcium oxide.

• Korean Chemical Engineering Research
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• 제46권6호
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• pp.1052-1056
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• 2008

소다 공정에서 탄산칼슘 결정의 평균입경과 형상 변화를 온도변화와 PAA 용액의 첨가에 대하여 연구하였다. 낮은온도($30^{\circ}C$, $60^{\circ}C$)에서는 Calcite 결정을, 높은 온도($80^{\circ}C$)에서는 Aragonite 결정을 얻었다. $30^{\circ}C$와 $80^{\circ}C$에서 용액에 PAA 용액을 첨가하여도 결정의 형상변화는 없었다. 중간온도($60^{\circ}C$)에서 PAA 용액을 첨가하여 Aragonite 결정을 얻었다. 결정의 형상변화가 PAA 분자 첨가로 인하여 일어났다. PAA 용액의 농도가 높을수록, 더 많은 Aragonite 결정을 얻었다. PAA 수용액의 농도가 높고 분자량이 클수록 탄산칼슘 결정의 평균입경은 증대하였으며, 형상변화가 일어나는 영역에서는 PAA의 분자량이 평균입경변화에 중요한 변수가 된다.

• 자원환경지질
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• 제18권2호
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• pp.177-184
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• 1985

The carbonate flat pebble conglomerates (CFPC) are interbedded as lenticular bed in the greenish rhythmite of the upper part of $Hwaj{\check{o}}l$ Formation, $Jos{\check{o}}n$ Supergroup. Pebbles are composed mainly of lime-mudstone with small amounts of bioclasts and silt-sized subangular quartz grains. The matrix among pebbles is composed mainly of sparry calcite with relatively much amounts of bioclasts, silt-sized subangular quartz grains and authigenic pyrite crystals or grains. The sparry calcite of the matrix seems to be the results of neomorphism of skeletal sands and bioclasts. The pebbles are well rounded and no plastic deformations are found. Some pebbles show the outer rim of glauconite. CFPC are not associated with any other intertidal features such as stromatolites, flaser bedding and channel structures. Also any features indicative of subaerial exposure such as dessication cracks, fenestrae and so on are not found in the bed. The sedimentological features of CFPC suggest that the following conditions appear to have been necessary for the formation of CFPC : 1) episodic deposition of thin, permeable calcareous beds separated argillaceous beds; 2) preservation of these beds near the sediment-water interface where they could become rapidly cemented; 3) erosion and redeposition of the partially lithified beds by storms or other exceptional erosional events. Eventually storm erosion and redeposition together represent only one of several critical conditions in the genesis of CFPC. The CFPC are very common in Cambrian and lower Ordovician formations, and become very rare in the younger carbonate formations. The expansion of infauna after Ordovician Period eliminated the widespread potential for rapid submarine cementation which is one of the critical factors to form CFPC.

• Journal of Microbiology and Biotechnology
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• 제31권9호
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• pp.1311-1322
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• 2021

Microbially induced calcium carbonate precipitation (MICP) has recently become an intelligent and environmentally friendly method for repairing cracks in concrete. To improve on this ability of microbial materials concrete repair, we applied random mutagenesis and optimization of mineralization conditions to improve the quantity and crystal form of microbially precipitated calcium carbonate. Sporosarcina pasteurii ATCC 11859 was used as the starting strain to obtain the mutant with high urease activity by atmospheric and room temperature plasma (ARTP) mutagenesis. Next, we investigated the optimal biomineralization conditions and precipitation crystal form using Plackett-Burman experimental design and response surface methodology (RSM). Biomineralization with 0.73 mol/l calcium chloride, 45 g/l urea, reaction temperature of 45℃, and reaction time of 22 h, significantly increased the amount of precipitated calcium carbonate, which was deposited in the form of calcite crystals. Finally, the repair of concrete using the optimized biomineralization process was evaluated. A comparison of water absorption and adhesion of concrete specimens before and after repairs showed that concrete cracks and surface defects could be efficiently repaired. This study provides a new method to engineer biocementing material for concrete repair.

• 한국광물학회지
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• 제17권1호
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• pp.11-21
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• 2004

자발적 침전법에 의하여 다양한 과포화 용액에서 탄산염광물을 합성하였다. 합성용액의 온도는 $25^{\circ}C$에서 유지 시켰고 pH범위는 6.9에서 8.8 이였다. 용액의 과포화도 조절 시 2가지 변수를 두어 농도를 변화 시켰다. (1) total carbonate의 농도와 total calcium의 농도비가 다음 세 가지 조건을 만족시키도록 변화시켰다: [C $O_3$]$_{Τ}$/[Ca]$_{Τ}$ >1. [C $O_3$]$_{Τ}$/[Ca]$_{Τ}$=1, and [C $O_3$]$_{Τ}$/[Ca]$_{Τ}$<1. (2) 앞서 언급한 조건에 total calcium의 농도를 0.02 mol/d $m^3$, 0.2 mol/d $m^3$, 그리고 0.4 mo1/d $m^3$이 되도록 변화 시켰다. [C $O_3$]$_{Τ}$/[Ca]$_{Τ}$$\geq$ 1의 조건 하에서 형성된 미립의 탄산염 광물은 대부분 거의 순수한 방해석으로 바테라이트가 1% 이하로 존재하였으며 이와는 달리 [C $O_3$]$_{Τ}$/[Ca]$_{Τ}$ < 1 조건하에서는 거의 순수한 바테라이트가 합성되었다. 본 연구 결과 탄산염광물의 상은 합성 용액상의 [C $O_3$]$_{Τ}$ 농도보다는 [C $O_3$]$_{Τ}$의 농도에 의하여 좌우되는 것으로 나타났다. 또한 바테라이트의 합성 결과는 [C $O_3$]$_{Τ}$/[Ca]$_{Τ}$의 비가 0.8 에서 0.5로 낮아짐에 따라 roughness가 증가하고 결과적으로 광물표면적이 5.64∼7.34 $\mu\textrm{m}$에서 8.39∼10.3 $\mu\textrm{m}$로 증가한다.

• 대한화학회지
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• 제13권2호
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• pp.131-136
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• 1969

The crystal structure of rubidium hydrogen carbonate has been determined by single crystal X-ray diffraction method. the crystals are monoclinic with a = 15.05 $\AA$, b = 5.83 $\AA$, c = 4.02 $\AA$, and $\beta$ = $107^{\circ}.$ There are four chemical units per unit cell and the space-group was fixed as $C2-C^3_2$. Patterson and trial-and-error methods gave the approximate structure and its refinements were made by two-dimentional Fourier summation. The Co3 group is planar with tshhe C-O distances of 1.32 $\AA$, 1.32 $\AA$, and 1.33 $\AA$ within experimental error and the two $CO_3$ groups are linked together to form a complex anion [$H_2C_2O_6$] with the O-H${\cdot}{\cdot}{\cdot}$O distance, 2.53 $\AA.$ Two molecules of $RbHCO_3$ make the dimer structure with two hydrogen bonds. The values of reliability factor for $F_{(hol)}$, $F_{(hko)}$and $F_{(okl)}$are 0.15, 0.15 and 0.17 respectively. Each rubidium ion has eight oxygen neighbours with the Rb-O distances of 2.84~3.11 $\AA.$.

• 한국인쇄학회지
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• 제13권1호
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• pp.13-24
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• 1995

The color filter os made in four methods ; dyeing, printing electrodisposition and pigment dispersed method. Among technologies for color filter manufacture, pigment-dispersed and hybrid method are dominant over all others in commercial manufacture of large scale, fine resolution color filter for liquid crystal display. In this paper to investigate the possibility of the color filter manufacture for LCD by screen printing method, we synthesyzed PVA/sbQ screen emulation for high resolution, estimated image of printed fine pattern and manufactured color filter by screen printing. Results of the study are as follow and found the screen printing method os useful and valid from it. 1. Fine pattern is formed due to photocyclodomerization of -C=C- bond at 342nm, on the other hand unexposured parts are removed in water. 2. sharpness and resolution of fine pattern is improved at mesh streching angle 22.5 and 45 than 0 degree. It is expected due to resistance between inks and mesh streching angles. 3. Spectral characteristics of sample inks were R(640nm), G(535nm), B(470nm), transmittance were R(92%), G(79%), B(70%) and chromaticity coordinate values were R(0.62,0.33), G(0.32,0.59), B(0.14,0.17)