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        검색결과 509

        141.
        2009.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        To understand molecular and cellular mechanisms of many gene products in the female reproductive organs including the ovary and uterine endometrium as well as during embryo development, researchers have developed and utilized many effective methodologies to analyze gene expression in cells, tissues and animals over the last several decades. For example, blotting techniques have helped to understand molecular functions at DNA, RNA and protein levels, and the reverse transcription-polymerase chain reaction (RT-PCR) method has been widely used in gene expression analysis. However, some conventional methods are not sufficient to understand regulation and function of genes expressed in very complex patterns in many organs. Thus, it is required to adopt more high-throughput and reliable techniques. Here, we describe several techniques used widely recently to analyze gene expression, including annealing control based-PCR, differential display-PCR, expressed sequence tag, suppression subtractive hybridization and microarray techniques. Use of these techniques will help to analyze expression pattern of many genes from small scale to large scale and to compare expression patterns of genes in one sample to another. In this review, we described principles of these methodologies and summarized examples of comparative analysis of gene expression in female reproductive organs with help of those methodologies.
        4,200원
        142.
        2009.05 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        Lotus-type porous nickel with cylindrical pores was fabricated by unidirectional solidification under an Ar gas atmosphere using the thermal decomposition method of the compounds such as sodium hydroxide, calcium hydroxide, calcium carbonate, and titanium hydride. The decomposed gas does form the pores in liquid nickel, and then, the pores become the cylindrical pores during unidirectional solidification. The decomposed particles from the compounds do play a rule on nucleation sites of the pores. The behavior of pore growth was controlled by atmosphere pressure, which can be explained by Boyle's law. The porosity and pore size decreased with increasing Ar gas pressure when the pores contain hydrogen gas decomposed from calcium and sodium hydroxide and titanium hydride, ; however it they did not change when the pores contain containing carbon dioxide decomposed from calcium carbonate. These results indicate that nickel does not have the solubility of carbon dioxide. Lotus-type porous metals can be easily fabricated by the thermal decomposition method, which is superior to the conventional fabrication method used to pressurized gas atmospheres.
        4,000원
        143.
        2009.05 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        Simple and high efficiency green phosphorescent devices using an intermixed double host of 4, 4', 4"-tris(N-carbazolyl) triphenylamine [TCTA], 1, 3, 5-tris (N-phenylbenzimiazole-2-yl) benzene [TPBI], phosphorescent dye of tris(2-phenylpyridine)iridium(III) [Ir(ppy)3], and selective doping in the TPBI region were fabricated, and their electro luminescent characteristics were evaluated. In the device fabrication, layers of 70Å-TCTA/90Å-TCTA[0.5TPBI0.5/90Å-TPBI doped with Ir(ppy)3 of 8% and an undoped layer of 50Å-TPBI were successively deposited to form an emission region, and SFC137 [proprietary electron transporting material] with three different thicknesses of 300Å, 500Å, and 700Å were used as an electron transport layer. The device with 500Å-SFC137 showed the luminance of 48,300 cd/m2 at an applied voltage of 10 V, and a maximum current efficiency of 57 cd/A under a luminance of 230 cd/m2. The peak wavelength in the electroluminescent spectral and color coordinates on the Commission Internationale de I'Eclairage [CIE] chart were 512 nm and (0.31, 0.62), respectively.
        4,000원
        144.
        2009.04 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        SnxSe100-X (15|X|30) alloys have been studied to explore their suitability as phase change materials for nonvolatile memory applications. The phase change characteristics of thin films prepared by a Radio Frequency (RF) magnetron co-sputtering system were analyzed by an X-ray diffractometer and 4-point probe measurement. A phase change static tester was also used to determine their crystallization under the pulsed laser irradiation. X-ray diffraction measurements show that the transition in sheet resistance is accompanied by crystallization. The amorphous state showed sheet resistances five orders of magnitude higher than that of the crystalline state in SnxSe100-X (x = 15, 20, 25, 30) films. In the optimum composition, the minimum time of SnxSe100-X alloys for crystallization was 160, 140, 150, and 30ns at 15mW, respectively. The crystallization temperature and the minimum time for crystallization of thin films were increased by increasing the amount of Sn, which is correlated with the activation energy for crystallization.
        3,000원
        145.
        2009.03 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        In this report, the structural and optical properties of sol-gel derived MgxZn1-xO thin films upon changes in the composition and annealing temperature were investigated. The Mg2+ content and the annealing temperature were varied in the range of 0≤x≤0.35 and 400˚C≤T≤600˚C, respectively. The films exhibited a hexagonal wurtzite structure of a polycrystalline nature. The optical transmittance exceeded 85% and the optical band gap of the film was tuned as high as 3.84 eV at a value of x = 0.35 (annealed at 400˚C), which was evidently the maximum Mg2+ content for the single-phase polycrystalline MgxZn1-xO thin films prepared in this experiment. The optical band gap and photoluminescence emission were tailored to the higher energy side while maintaining crystallinity without a significant change of the lattice constant.
        4,000원
        146.
        2009.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Ovarian cancer is a significant cause of cancer-related death in women, but the main biological causes remain open questions. Hormonal factors have been considered to be an important determinant causing ovarian cancer. Recent studies have shown that gonadotropin-releasing hormone (GnRH)-I and its analogs have clinically therapeutic value in the treatment of ovarian cancer. In addition, numerous studies have shown that the potential of GnRH-II in normal reproductive system or reproductive disorder. GnRH-I receptors have been detected in approximately 80% of ovarian cancer biopsy specimens as well as normal ovarian epithelial cells and immortalized ovarian surface epithelium cells. GnRH-II receptors have also been found to be more widely expressed than GnRH-I receptors in mammals, suggesting that GnRH receptors may have additional functions in reproductive system including ovarian cancer. The signal transduction pathway following the binding of GnRH to GnRH receptor has been extensively studied. The activation of protein kinase A/C (PKA/PKC) pathway is involved in the GnRH-I induced anti-proliferative effect in ovarian cancer cells. In addition, GnRH-I induced mitogen-activated protein kinase (MAPK) activation plays a role in anti-proliferative effect and apoptosis in ovarian cancer cells and the activation of transcriptional factors related to cellular responses. However, the role of GnRH-I and II receptors, there are discrepancies between previous reports. In this review, the role of GnRH in ovarian cancer and the mechanisms to induce anti-proliferation were evaluated.
        4,600원
        147.
        2009.02 KCI 등재 구독 인증기관 무료, 개인회원 유료
        탐구는 학교과학에서 지속적으로 강조되어 왔다. 하지만 학교에서 주어지는 문제는 학생들이 일상생활에서 경험하고 부딪치는 문제들과는 여러 면에서 다르다. 본 연구의 목적은 학생들이 문제에 대한 인지도식을 거의 갖고 있지 않을 때, 과제에 대한 태도와 사고력이 문제해결과정, 특히, 문제공간의 형성과 정교화에 어떻게 영향을 미치는지를 알아보는 것이다. 이를 위하여 연구자는 미국의 한 영재센터 여름방학 프로그램 중 4-6학년 영재학생 대상 '레고 로봇 수업'에 참여한 학생들의 문제해결전략을 추적하였다. 결과는 다음과 같다. (1) 과제의 선택과 파악방법, 작동자에 대한 인식의 차이 등 과제에 대한 태도는 서로 다른 문제공간을 형성하게 하였다. (2) 분석적 사고, 융통성, 효율적인 정교화 기술, 기존 인지도식의 적용 등의 사고력의 수준 차이는 문제공간의 정교화 차이와 문제해결의 성공여부로 이어졌다. (3) 초기의 문제공간의 차이는 문제해결전략의 형성 차이를 가져왔지만, 사고력 없이는 효과적인 문제해결전략의 정교화가 이루어지지 못하였다. 마지막으로, 위의 결과를 바탕으로 과학탐구를 증진시킬 몇 가지 사항이 제안되었다.
        4,200원
        148.
        2009.02 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        The effect of annealing under argon atmosphere on hydrogenated amorphous silicon (a-Si:H) thin films deposited at room temperature and 300˚C using Radio Frequency (RF) magnetron sputtering has been investigated. For the films deposited at room temperature, there was not any increase in hydrogen content and optical band gap of the films, and as a result, quality of the films was not improved under any annealing conditions. For the films deposited at 300˚C, on the other hand, significant increases in hydrogen content and optical band gap were observed, whereas values of microstructure parameter and dark conductivity were decreased upon annealing below 300˚C. In this study, it was proposed that the Si-HX bonding strength is closely related to deposition temperature. Also, the improvement in optical, electrical and structural properties of the films deposited at 300˚C was originated from thermally activated hydrogen bubbles, which were initially trapped at microvoids in the films.
        4,000원
        149.
        2009.02 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        Nano-crystalline hydroxyapatite (HAp) films were formed at the Ti surface by a single-step microarc oxidation (MAO), and HAp-zirconia composite (HZC) films were obtained by subsequent chemical vapor deposition (CVD) of zirconia onto the HAp. Through the CVD process, zero- and one-dimensional zirconia nanostructures having tetragonal crystallinity (t-ZrO2) were uniformly distributed and well incorporated into the HAp crystal matrix to form nanoscale composites. In particular, (t-ZrO2) was synthesized at a very low temperature. The HZC films did not show secondary phases such as tricalcium phosphate (TCP) and tetracalcium phosphate (TTCP) at relatively high temperatures. The most likely mechanism for the formation of the t-ZrO2 and the pure HAp at the low processing temperature was proposed to be the diffusion of Ca2+ ions. The HZC films showed increasing micro-Vickers hardness values with increases in the t-ZrO2 content. The morphological features and phase compositions of the HZC films showed strong dependence on the time and temperature of the CVD process. Furthermore, they showed enhanced cell proliferation compared to the TiO2 and HAp films most likely due to the surface structure change.
        4,000원
        150.
        2009.01 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        Conjugated nanocrystals using CdSe/ZnS core/shell nanocrystal quantum dots modified by organic linkers and glucose oxidase (GOx) were prepared for use as biosensors. The trioctylphophine oxide (TOPO)-capped QDs were first modified to give them water-solubility by terminal carboxyl groups that were bonded to the amino groups of GOx through an EDC/NHS coupling reaction. As the glucose concentration increased, the photoluminescence intensity was enhanced linearly due to the electron transfer during the enzymatic reaction. The UV-visible spectra of the as-prepared QDs are identical to that of QDs-MAA. This shows that these QDs do not become agglomerated during ligand exchanges. A photoluminescence (PL) spectroscopic study showed that the PL intensity of the QDs-GOx bioconjugates was increased in the presence of glucose. These glucose sensors showed linearity up to approximately 15 mM and became gradually saturated above 15 mM because the excess glucose did not affect the enzymatic oxidation reaction past that amount. These biosensors show highly sensitive variation in terms of their photoluminescence depending on the glucose concentration.
        4,000원
        151.
        2008.12 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        ZnO/ZnS core/shell nanocrystals (~5-7 nm in diameter) with a size close to the quantum confinement regime were successfully synthesized using polyol and thermolysis. X-ray diffraction (XRD) and high-resolution transmission electron microscopy (HRTEM) analyses reveal that they exist in a highly crystalline wurtzite structure. The ZnO/ZnS nanocrystals show significantly enhanced UV-light emission (~384 nm) due to effective surface passivation of the ZnO core, whereas the emission of green light (~550 nm) was almost negligible. They also showed slight photoluminescence (PL) red-shift, which is possibly due to further growth of the ZnO core and/or the extension of the electron wave function to the shell. The ZnO/ZnS core/shell nanocrystals demonstrate strong potential for use as low-cost UV-light emitting devices.
        4,000원
        152.
        2008.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        열적으로 불안정한 강착원반의 비선형 유체역학적 모형에 기초하여 블랙홀 마이크로케이사의 광폭발 한계 순환주기에 대한 원반 질량의 시간적 진화 모형을 계산하였다. 블랙홀의 질량, 원반 크기 및 질량 유입률과 같은 물리적인 매개변수들은 블랙홀 X선 신성의 원형인 A0620-00에서 관측된 역사적인 1975 광폭발을 재현하도록 선택되었다. 중심부에서 원반으로 쪼여지는 조사(照射)의 시간에 따른 효과는 직접 조사와 원반위의 뜨거운 강착 흐름으로부터 굴절되어 원반에 쪼여지는 간접조사의 두 가지 방법이 고려되었다. 우리의 강착원반 열적 불안정성 모형은 광폭발의 순환과정 전반에 걸쳐 X-선 변광체들에서 관측된 광도의 전형적인 복사 광도를 설명할 수 있다. 강착원반의 최대질량 ∼4.03×1024g은 광폭발의 점화 때에 얻어지며, 최소질량 ∼8.54×1023g은 차가운 쇠퇴기와 정지기(靜止期) 때에 이루어진다. 원반의 질량은 광폭발 한계 순환주기에 걸쳐 약 5배 정도 변한다.
        4,000원
        153.
        2008.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        2007년 1월 20일 규모 4.8의 오대산 지진 관측기록을 사용하여 강진동 발생에 있어서 지각구조의 영향을 조사하였다. 이를 위하여 강진동을 발생시키는 위상을 규명하였으며, 지진위험성 평가에 있어서의 의미를 고찰하였다. 관측자료와 파형모사 분석 결과, 지각-맨틀 경계에서 반사된 파가 예상보다 큰 지진동을 발생시킴을 확인하였다. 본 연구는 우리나라와 같은 지진활동이 많지 않은 지역에서도 지진위험저감 연구에서 지각구조를 고려하여야 함을 보여주고 있다.
        4,000원
        154.
        2008.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        We separately cultured follicular oocytes collected from individual ovaries of slaughtered Korean native cows and examined both the embryonic development rate and pregnancy rate after embryo transplantation according to the meat yield and quality grades of the source beef carcass. Oocytes from meat yield grade B cows exhibited a higher fertilization rate and embryonic developmental rate to the eight-cell stage than oocytes from grade A or C animals (p<0.05), but there was no significant difference in rate of development to the blastocyst stage among meat yield grades A, Band C. The oocyte cleavage rate and development rate to the eight-cell stage from meat quality grade 3 cattle was higher than grades 1++, 1+, 1 and 2 (p<0.05). Embryos derived from grade animals displayed a development rate to the blastocyst stage of 19.4%, which was also higher than all other meat quality grades (p<0.05). Transplantation of in vitro-cultured oocytes from meat yield grade A ovaries led to a higher pregnancy rate (64.2%) than in vitro-cultured oocytes from meat yield grade B ovaries (56.5%), but there was no significant difference between the two groups in pregnancy or abortion rates. In conclusion, embryonic development rate and pregnancy rate has a close relation to meat quality grades of the source beef carcass, this results is to give information for the Korean native cows improvement of breed.
        4,000원
        155.
        2008.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The ability to preselect the sex of piglets is advantageous in the pig industry. The objective of this study was to examine the feasibility of using intracytoplasmic sperm injection (ICSI) with sorted spermatozoa to produce piglets with a preselected sex. Pig embryos were produced by ICSI of frozen X- and Y-sperm that had been separated by flow cytometry. The developmental competence of the embryos was investigated in vitro and in vivo. The populations of X- and Y-spermatozoa were 52.7% and 47.3%, respectively in our samples. The in vitro development of ICSI embryos was enhanced by longer of in vitro maturation of oocytes ( vs. ). Their cleavage () and blastocyst formation () rates were not significantly different between male and female ICSI embryos, or between sorted and unsorted sperm-derived embryos. One pregnancy was established in a recipient that was transferred with 110 female ICSI embryos, but the pregnancy was terminated on Day 89 of gestation. Our results suggest that the separation X- and Y-spermatozoa by flow cytometric sorting can be a useful tool in combination with ICSI for the production of pig embryos and piglets of preselected sex.
        4,000원
        156.
        2008.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        In A Vision Yeats combines Christianity with elements as disparate as theosophy, astrology, neoPlatonism, spiritualism, the magic and Cabbalistic traditions, the work of writers such as Swedenborg, Boehme and Blake. The end result, such as “Ego Dominus Tuus” and “The Second Coming”, is a unitary system in which Yeats defines his ideas on history, religion and art. “The Second Coming” depicts an apocalyptic scene, and the advent of a “rough beast” oxymoronically slouching towards Bethlehem “to be born.” In accordance with Yeats’s view on cosmic and historical cycles, which will be touched upon in this essay, it is generally regarded as prophesizing the end of the “twenty centuries” of the Christian Era. It embodies or foreshadows the revelation of the character of the age to come, completely antithetical to that of the Christian Era, which, in Yeats’s mind, was nearing its conclusion. The poem’s title, its biblically allusive infrastructure, and its Latin evocation of a “Spiritus mundi” (namely, “soul of the world”) disclose its intention to cast an appeal on the “collective unconscious” of the entire Christian world Such a coexistence of opposite forces would also conform perfectly with Yeats’s view of Unity of Being, which entails a detached and simultaneous outlook on both Good and Evil. Yeats seems to have accessed this “antithetical” state of consciousness in “The Second Coming”, where the triumphal Christian connotations evoked by the title are offset by the terrifying scenario in the poem, which describes what is in fact a reverse apocalypse and the coming of the Antichrist. On its most evident plane, Yeats’s “The Second Coming” is, obviously, the description of an apocalyptic (or anti-apocalyptic) scene.
        5,800원
        157.
        2008.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        In A Vision, Yeats provides multiple trans-temporal (crossing different periods in history) and trans-national(crossing different nations) collage of “the glance characteristic of a civilization in its final phase,” and provides different images of eyes for each period. Each of these images is related to a certain point between concernful dealing with the world and the vision of the infinite world. Each image of the gaze characteristic of sculpture represents a civilization, and constitutes a “discontinuous image” which connotes “the symbolic message.” In fact, Yeats reveals each image of the eye as a fragment or stasis of a moment of the spiritual eye, and at the same time as the representation of Yeats's intention to quest for the Unity of Culture, the “vast design” of his transnational poetics. The objective of this paper is to trace the trajectory of Yeats's poetics and rhetoric. My contention is that Yeats reveals his major shift from the poetics to the rhetoric in the midst of the multi-level “twists and turns” which mark an important manifestation of the process of transmigration toward the Unity of Culture, and I argue that Yeats’s quest for the Unity of Culture manifest a transnational poetics. Yeats’s poetic development manifests the on-going process of contestation and fragmentation on the bridge between the poetics and the rhetoric. The bridge is a site of turbulent aporia site in which duplication of contestation creates a simultaneous centripetal and centrifugal movement, comingled with multiplication of fragmentation. Between “Magic” essay and A Vision, there is a missing link to establish the so-called “linguistic turn” in the career of Yeats the transnational poet/theorist. Yeats in his Per Amica Silentia Lunae already conceived the doubling intertext of intentionality as an anchoring center of the breakthrough out of the dilemma of the theory of magic. In fact, what Yeats has done in Per Amica Silentia is to create conflict, tension, and equilibrium between the theory of magic and the theory of the linguistic turn, thereby rupturing the inauthentic theory of correspondence and establishing the foreground of the authentic concept of correspondence in terms of Othering. The Only Jealousy of Emer is the dramatic manifestion of Yeats’s linguistic turn in the speech of the characters in relation to the desire of the Other. My focus here in this play is rather the role of the multiple masks which represent the nature of the Other as well as the process of Othering. The Other has been represented by the multiple characters’ masks such as those of Bricriu (The Figure of Cuchulain), Fand (Woman of the Sidhe), The Ghost of Cuchulain, Emer, Eithne Inguba. As a unified vision of Yeats’s own diachronic and synchronic transnational poetics, A Vision can be seen in terms of Deleuze and Guattari’s “desiring- production.” Opposed to the (negative) Lacanian dialectic of lack and desire, Deleuze and Guattari propose a theory of “desiring-production,” which they define as a “pure multiplicity, that is to say, an affirmation that is irreducible to any sort of unity.” If we re-consider A Vision as a desiring-machine that is connected to other desiring-machines, we deterritorialize the perspective which constructs lack as the centre of subjectivity, thereby reterritorializing subjectivity as a network of multiplicities. The gaze of the writing subjects in A Vision become autonomous, creating automatic writing and automatic speech. Then, A Vision which is given for the metaphors for poetry and poetry achieves its being in language. In short, Yeats has established a transnational poetics which traces its poetics of the Other and Othering back to the poetics and the rhetoric of the linguistic turn, a turn in which poetry exists in language and turned toward an inner reality.
        5,400원
        158.
        2008.09 KCI 등재 구독 인증기관 무료, 개인회원 유료
        This study observed the upper tropospheric ozone enhancement in the northern Atlantic for the Aerosols99 campaign in January-February 1999. To find the origin of this air, we have analyzed the horizontal and vertical fields of Isentropic Potential Vorticity (IPV) and Relative Humidity (RH). The arch-shaped IPV is greater than 1.5 pvus indicating stratospheric air stretches equatorward. These arch-shaped regions are connected with regions of RH less than 20%. The vertical fields of IPV and RH show the folding layer penetrating into the upper troposphere. These features support the idea that the upper tropospheric ozone enhancement originated from the stratosphere. Additionally, we have investigated the climatological frequency of stratospheric intrusion over the tropical north Atlantic using IPV and RH. The total frequency between the equator and 30˚N over the tropical north Atlantic exhibits a maximum in northern winter. It suggests that the stratospheric intrusion plays an important role in enhancing ozone in the upper troposphere over the tropical north Atlantic in winter and early spring. Although the tropospheric ozone residual method assumed zonally invariant stratospheric ozone, stratospheric zonal ozone variance could be caused by stratospheric intrusions. This implies that stratospheric intrusion influences ozone variance over the Atlantic in boreal winter and spring, and the intrusion is a possible source for the tropical north Atlantic paradox.
        4,000원
        159.
        2008.09 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The absolute age of lapilli tuff in sedimentary formation that contains dinosaur fossils in the Boseong area, Korea was determined radiometrically against volcanic rocks below and above the fossil-bearing horizons. The sanidine in the lapilli tuff below the fossil-bearing horizon (Seonso formation) has an 40Ar-39Ar age of 81.l±1.4Ma. The Pilbong tuff above Seonso formation has an 40Ar-39Ar age of 81.0±2.4Ma. An andesite dyke intruding all sedimentary units yields an 40Ar-39Ar age of 42.4±2.5Ma. Thus 81 Ma age can be regarded as the best estimate for the age of the Seonso Formation and the associated the dinosaur eggs. This age correlates well with dinosaur fossil finds in the Haenam and Koseong regions of Korea. The occurrence of dinosaur eggs and clutches attests to the existence of dinosaurs in southern Korea at least inCampanian times.
        4,000원
        160.
        2008.06 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        A preparation of NixMn1-xFe2O4 nanoparticles produced via the reduction of Nickel nitrate hexahydrate, Manganese (II) nitrate hexahydrate and Iron nitrate nonahydrate with hydrazine in Igepal CO-520/cyclohexane reverse micelle solutions was investigated. Transmission Electron Microscope (TEM), X-ray Diffraction (XRD) and Vibration Sample Magnetometer (VSM) analyses showed that the resultant nanoparticles increased the molar ration of water to Igepal CO-520 as the concentrations of Nickel nitrate hexahyrate, Manganese (II) nitrate hexahydrate and Iron nitrate nonahydrate increased. The average size of the synthesized particles calcined at 600˚C for 2hrs was in the range of 20 nm to 30 nm, and the particle distribution was broadened. The phase of the synthesized particles was crystalline, and the magnetic behavior of the synthesized particles was superparamagnetism. The effect of the synthesis parameters of the molar ratio of water to surfactant and the calcination temperature was discussed.
        3,000원