• Journal of the Mineralogical Society of Korea
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• v.22 no.2
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• pp.115-127
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• 2009

Mineral quantification was performed on sediments of the Ulleung basin by X-ray powder diffraction and the computer software based on Rietveld quantification method. The sediments are dominated by amorphous opal-A with quartz, feldspars, micas, clays, calcite, and pyrite. The opal-A shows iterative variation in abundance with increasing burial depth. In addition, the relative abundance of opal-A is coincident with abundance of organic carbon contents, indicating that the Ulleung sediment consists mostly of amorphous silica derived from organism in the pelagic environment. Upward increase in the abundance of opal-A is markedly shown in the cores located in the slope region. On the other hand, there is a distinct tendency that the abundance of calcite is inversely proportional to that of opal-A. This indicates that the abundance of opal-A increases during the rise of sea level. Also, the fall of sea level lowers the abundance of opal-A.

• The Journal of the Convergence on Culture Technology
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• v.8 no.6
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• pp.59-65
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• 2022

The baby boomers born between 1955 and 1974, recently called the new age, form a huge population group and show characteristics different from the previous traditional older generations. With the retirement of those who make up 33% of the nation's population in earnest, the emergence of a new generation of the elderly population and policy changes are required. The new middle age generation, also called the opal generation, want to spend their old age productively and autonomously, which has increased due to the increase in life expectancy, and have some economic ability, such as enjoying overseas travel in old age. As preparation for old age is insufficient, policy attention is required for the younger generation as a new generation. In this paper, focusing on the baby boom generation, the definition of the opal generation, their consumption lifestyle, attitudes, social activities, leisure activities, and lifestyle such as health efforts are investigated, and job creation, social re-education, and local It is intended to present practical measures for preparing for old age, such as the establishment of medical facilities and social consideration for a leisurely cultural life.

• Clean Technology
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• v.18 no.1
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• pp.38-42
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• 2012

Photonic crystals (PCs) are highly ordered porous materials which have been much attention because of its potential for controlling the light sauces. There are many methods for synthesizing this kind of materials among them we chose the supercritical deposition. With this method the reactants can easily infiltrate into the complex structure. In this paper, supercritical carbon dioxide ($scCO_2$) was used as a reaction medium, which is known as a sustainable solvent due to its nontoxic and noninflammable characteristics. We coated the colloidal template with metal alkoxide by using $scCO_2$ and then obtained macro-porous inverse opals. The reaction was carried out at $40^{\circ}C$ and 80 bar. We synthesized two different inverse opals which called silica and titania inverse opals by use of tetraethyl orthosilicate (TEOS) and titanium isopropoxide (TTIP) as a precursor, respectively.

• 한국신재생에너지학회:학술대회논문집
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• 2007.06a
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• pp.504-506
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• 2007

동해 울릉분지에서 채취된 피스톤 코어 시료의 퇴적상과 유기물 특성을 대비하였다. 코어 시료의 퇴적상은 크게 홀로세 생물교란된 뻘 퇴적상과 빙하기의 다양한(생물교란된, 엽리가 발달된) 뻘 퇴적상으로 구분되었다. 코어 시료의 유기물 특성은 총유기탄소함량과 퇴적물 밝기($L^{\ast}$), 석영 함량, 오팔A 함량을 대비하여 밝혔다. 총유기탄소함량은 퇴적물 밝기와 높은 상관계수를 가진다. 코어 시료의 석영 함량은 총유기탄소함량과 퇴적시기에 따른 상관관계의 차이를 보이는데, 이것은 퇴적기작 차이에 의한 것으로 해석된다. 그리고 오팔 A와 총유기탄소함량의 상관관계는 퇴적장소에 따라 차이를 갖는다. 동해 울릉분지 코어 시료는 총유기탄소함량과 퇴적물 밝기가 높은 상관계수를 갖는데, 이것은 초기속성작용의 영향이 크지 않았음을 지시하는 것이다. 후기 홀로세에서는 총유기탄소함량이 거의 일정한 구간에서도 오팔A 함량이 큰 차이가 나타나는데, 이것은 퇴적장소에 따라 고해양 생산력의 차이가 있었음을 지시하는 것이다.

• Korean Chemical Engineering Research
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• v.51 no.6
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• pp.727-732
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• 2013

In this report, we present an inverse opal scaffold that can enhance the chondrogenic differentiation of human adipose-derived stem cells (hADSCs) without drug, gene, or cytokine supplement. Inverse opal scaffolds based on poly(D,L-lactide-co-glycolide) were formed with uniform $200{\mu}m$ pores. Due to uniform pore sizes and well-controlled interconnectivity of inverse opal scaffold, hADSCs were allowed to distribute homogeneously throughout the scaffolds. As a result, high cell density culture with scaffold was possible. Since the hADSCs cultured in inverse opal scaffolds were subjected to limited supplies of oxygen and nutrients, these cells were naturally preconditioned to a hypoxic environment that stimulated the up-regulation of hypoxia-inducible factor-$1{\alpha}$ (HIF-$1{\alpha}$). As a result, apoptotic activity of hADSCs until 3 weeks after initial cell seeding was significantly reduced and chondrogenic differentiation related molecular signal cascades were up regulated (transforming growth factor-beta, phosphorylated AKT, and phosphorylated p38 expression). In contrast, hADSCs cultured with small and non-uniform porous scaffolds showed significantly increased apoptotic activity with decreased chondrogenic differentiation. Taken together, inverse opal scaffold could potentially be used as an effective tool for improving chondrogenesis using stem cells.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.14 no.3
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• pp.134-144
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• 2009

Paleoproductivity changes in the central part of the Bering Sea since the last glacial period were reconstructed by analyzing opal and total organic carbon (TOC) content and their mass accumulation rate (MAR) in sediment core PC23A. Ages of the sediment were determined by both AMS $^{14}C$ dates using planktonic foraminifera and Last Appearance Datum of radiolaria (L. nipponica sakaii). The core-bottom age was calculated to reach back to 61,000 yr BP. and some of core-top was missing. Opal and TOC contents during the last glacial period varied in a range of 1-10% and 0.2-1.0%, and their average values are 5% and 0.7%, respectively. In contrast, during the last deglaciation, opal and TOC contents varied from 5 to 22% and from 0.8 to 1.2%, respectively, with increasing average values of 8% and 1.0%. Opal and TOC MAR were low ($1gcm^{-2}kyr^{-1}$, $0.2gcm^{-2}kyr^{-1}$) during the last glacial period, but they increased (>5 and >$1gcm^{-2}kyr^{-1}$) during the last deglaciation. High diatom productivity during the last deglaciation was most likely attributed to the elevated nutrient supply to the sea surface resulting from increased melt water input from the nearby land and enhanced Alaskan Stream injection from the south under the restricted sea-ice and warm condition during the rising sea level. On the contrary, low productivity during the last glacial period was mainly due to decreased Alaskan Stream injection during the low sea-level condition as well as to extensive development of sea ice under low-temperature seawater and cold environment.

• Journal of the Mineralogical Society of Korea
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• v.28 no.1
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• pp.71-81
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• 2015

This study was carried out in order to investigate the mineralogical characteristics of the core sediments (03GHP-02 and HB13-2), obtained from the Ulleung Basin and Hupo Basin, Korea. The results on mineral compositions, clay mineral compositions, and the total contents and sequential extraction of different fractions of the phosphorus in core samples showed that those values are different in two cores and also at different depths. In both samples, mineral compositions were the same, composed mainly of quartz, microcline, albite, calcite, opal A, pyrite, and clay minerals (illite, chlorite, kaolinite, and smectite). However, the sample from Hupo Basin contains more opal A. Both samples, especially the ones from Hupo Basin contains more smectite than those reported from East Sea, indicating the influence of paleo-Hwangwei River and the Tertiary Formation of Korea Peninsula. For the samples from Uleung Basin, at 0.7-3.5 m range in depth, the low content of opal A and the low illite crystallinity index can be inferred to indicate the relatively cool climate, corresponding to the ice age. Also, the content of total phosphorus was low in those samples. It was reported that East Sea at that time was isolated from the neighboring seas due to the decrease of the sea level, and as a result, the influx of sediments was supposed to be little through the strait and rivers. For the samples from Hupo Basin, there is no significant changes in clay mineral composition and the distribution of phosphorus with increasing depth. This little change can be interpreted to indicate that the sediments comprising the core might be deposited in a relatively short period of time or deposited in sedimentary environment in which there's no significant changes in sediment supplies. The values of crystallinity index of clay minerals are high in those samples, indicating that it was relatively warm during that time. Although the increase of fluctuation pattern can be observed, showing that the climate of this period often changed, it is supposed that it was generally warm.

• Journal of the Korea Concrete Institute
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• v.19 no.5
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• pp.577-584
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• 2007

The effect of steel microfibers (SMF) on alkali-silica reaction (ASR) was investigated using two types of reactive aggregates, crushed opal and a pyrex rod of constant diameter. Cracks are less visible in the SMF mortars compared with the unreinforced mortars. Due to crack growth resistance behavior in SMF mortar specimens, the strength loss is eliminated and the ASR products remained well confined within the ASR site. The expansion and the ASR products were characterized by microprobe analysis and inductively coupled plasma (ICP) spectroscopy. The confinement due to SMF resulted in a higher Na and Si ion concentration of the ASR liquid extracted from the reaction site. The higher concentration reduced the ASR rate and resulted in a lower reactivity of the reactive pyrex rods in SMF mortars.

• Journal of Powder Materials
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• v.23 no.3
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• pp.189-194
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• 2016

We report a facile method for preparing KIT-1 mesoporous silicates with two different macroporous structures by dual templating. As a template for macropores, polystyrene (PS) beads are assembled into uniform three dimensional arrays by ice templating, i.e., by growing ice crystals during the freezing process of the particle suspension. Then, the polymeric templates are directly introduced into the precursor-gel solution with cationic surfactants for templating the mesopores, which is followed by hydrothermal crystallization and calcination. Later, by burning out the PS beads and the surfactants, KIT-1 mesoporous silicates with macropores are produced in a powder form. The macroporous structures of the silicates can be controlled by changing the amount of EDTANa4 salt under the same templating conditions using the PS beads and inverse-opal or hollow structures can be obtained. This strategy to prepare mesoporous powders with controllable macrostructures is potentially useful for various applications especially those dealing with bulky molecules such as, catalysis, separation, drug carriers and environmental adsorbents.

• Korean Journal of Materials Research
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• v.29 no.8
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• pp.491-496
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• 2019

In this study, we prepare pure $WO_3$ inverse opal(IO) film with a thickness of approximately $3{\mu}m$ by electrodeposition, and an ultra-thin $TiO_2$ layer having a thickness of 2 nm is deposited on $WO_3$ IO film by atomic layer deposition. Both sets of photoelectrochemical properties are evaluated after developing dye-sensitized solar cells(DSSCs). In addition, morphological, crystalline and optical properties of the developed films are evaluated through field-emission scanning electron microscopy(FE-SEM), High-resolution transmission electron microscopy(HR-TEM), X-ray diffraction(XRD) and UV/visible/infrared spectrophotometry. In particular, pure $WO_3$ IO based DSSCs show low $V_{OC}$, $J_{SC}$ and fill factor of 0.25 V, $0.89mA/cm^2$ and 18.9 %, achieving an efficiency of 0.04 %, whereas the $TiO_2/WO_3$ IO based DSSCs exhibit $V_{OC}$, $J_{SC}$ and fill factor of 0.57 V, $1.18mA/cm^2$ and 50.1 %, revealing an overall conversion efficiency of 0.34 %, probably attributable to the high dye adsorption and suppressed charge recombination reaction.