• 제목/요약/키워드: Transition Phase

검색결과 1,987건 처리시간 0.03초

Bridgeman 성장 [011] 분극 Mn:PIN-PMN-PT 압전단결정의 물성 분포 연구 (A Study on Property Distribution of [011] Poled Mn:PIN-PMN-PT Single Crystals Grown by Bridgeman Method)

  • 임수현;제엽;조요한;이상구;서희선
    • 한국전기전자재료학회논문지
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    • 제37권4호
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    • pp.412-419
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    • 2024
  • Mn-doped Pb(In1/2Nb1/2)O3-Pb(Mg2/3Nb1/3)O3-PbTiO3 (Mn:PIN-PMN-PT) single crystals, which exhibit improved phase transition temperatures and coercive field properties compared to Pb(In1/2Nb1/2)O3-Pb(Mg2/3Nb1/3)O3-PbTiO3 (PIN-PMN-PT) single crystals, are expected to be utilized in high-power acoustic transducers. Bridgeman method, growing single crystals along the axial direction from melt, is most widely used method for single crystal growth with large size and high quality. However, single crystal boules grown by the Bridgeman method demonstrate a PT compositional variation, giving rise a distribution of crystal structure and material properties along the growing axis. To employ piezoelectric single crystals grown by the Bridgeman method for acoustic transducers, it is essential to investigate their overall property distribution. In this study, the compositional distribution and property variation of Mn:PIN-PMN-PT single crystals grown by the Bridgeman method was investigated. Measured compositional distribution of PT was from 29% to 32.5% in the Rhombohedral crystal region of the boule. Two types of specimen, [011]-poled Mn:PIN-PMN-29PT and Mn:PIN-PMN-32PT single crystals, were fabricated and tested to obtain full property variation at both ends of the Rhombohedral crystal region. The properties related to the 32 directional vibration mode and the properties related to high-power driving were measured to confirm the overall distribution of properties by composition.

전기 열량 소자로의 응용을 위한 K(Ta0.70Nb0.30)O3/K(Ta0.55Nb0.45)O3 이종층 박막의 구조적, 전기적 특성 (Structural and Electrical Properties of K(Ta0.70Nb0.30)O3/K(Ta0.55Nb0.45)O3 Heterolayer Thin Films for Electrocaloric Devices)

  • 박병준;육지수;이삼행;이명규;박주석;이성갑
    • 한국전기전자재료학회논문지
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    • 제37권3호
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    • pp.297-303
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    • 2024
  • In this study, KTN heterolayer thin films were fabricated by alternately stacking films of K(Ta0.70Nb0.30)O3 and K(Ta0.55Nb0.45)O3 synthesized using the sol-gel method. The sintering temperature and time were 750℃ and 1 hour, respectively. All specimens exhibited a polycrystalline pseudo-cubic crystal structure, with a lattice constant of approximately 0.398 nm. The average grain size was around 130~150 nm, indicating relatively uniform sizes regardless of the number of coatings. The average thickness of a single-coated film was approximately 70 nm. The phase transition temperature of the KTN heterolayer films was found to be approximately 8~12℃. Moreover, the 6-coated KTN heterolayer film displayed an excellent dielectric constant of about 11,000. As the number of coatings increased, and consequently the film thickness, the remanent polarization increased, while the coercive field decreased. The 6-coated KTN heterolayer film exhibited a remanent polarization and coercive field of 11.4 μC/cm2 and 69.3 kV/cm at room temperature, respectively. ΔT showed the highest value at a temperature slightly above the Curie temperature, and for the 6-coated KTN heterolayer film, the ΔT and ΔT/ΔE were approximately 1.93 K and 0.128×10-6 K·m/V around 40℃, respectively.

노인 운동행위 변화단계별 중재프로그램의 개발 및 평가 - 범이론적 모형의 적용 - (Development and Evaluation of a Stage Matched Exercise Intervention Program for Elders - Application of the Tran Theoretical Model -)

  • 권윤정
    • 지역사회간호학회지
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    • 제13권2호
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    • pp.205-215
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    • 2002
  • Objectives: This study was designed to develop and evaluate a stage matched exercise intervention program to effectively increase exercise behaviors in urban elders. Methods: The study included three phases: preliminary descriptive data collection, program development, and program evaluation. The data for the preliminary descriptive phase were collected between May and June 2001. The study participants were 89 urban elders who responded a questionnaire that included general characteristics, exercise related experiences, stage, and process of change in exercise behaviors. Data were analyzed using descriptive statistics, $x^2$-test, and content analysis. Development of the program was based on the preliminary data. and a literature review, and was guided by the tran theoretical model. It consisted of strategies to facilitate the process of changes used in each stage. Evaluation of the program was achieved from October to December 2001, using a case study method, in which eight urban female elders participated. Interviews were conducted on a weekly basis in the form of either an individual interview, or group discussion. Each elder subject received education in accordance with the program strategies and education materials. In the case that a subject's stage of change moved into another one, the scores for the process of change were re-measured. The data were analyzed using the content analysis technique. Results: The results were as follows: 1. Elders who participated in the preliminary data collection phase were over 75 years of age, and the majority of them were women. They had a higher educational level, and fewer number of illnesses than the subjects in other studies. Their stage of change was divided into pre-contemplation and maintenance. The social liberation scores were the highest across all stages of change. There was no difference between men and women on scores for processes of change in each stage. 2. The stage matched exercise intervention program that was developed in this study consisted of one counseling type program and three distinguished educational booklet materials. 3. The results of the case studies are as follows: 1) The study participants were 8 women between 75 and 87 years of age. At the first interviews, all of them were in the pre-contemplation stage. All of them reached the action stage before the 7th week. The scores for processes of change that were the focus in each stage increased more than the scores for other processes of change. During the early stages of change, experimental processes increased more than behavioral processes. However. this pattern was reversed during later stages of change. 2) Characteristics of the subjects in each stage were identical as presented at the tran theoretical model. The intervention strategies were effective in the transition occurred in any stage. 3) Barriers for exercise included unwillingness to exercise, fatigue, shortness of breath, and pain. Ways to overcome these barriers were 'learning an alternative exercise method that can be done at home', 'self-promising/ exercise-promising', and 'use of cues to exercise'. 4) The factors that affected the application of the program were consideration of age and personal preference in selecting an exercise pattern, individualized intervention, and use of education materials appropriate to elders. Women over 80 years of age preferred muscle strengthening and stretching exercise, because they can be easily done at home. They also preferred individualized interventions, materials that were easy to read, and education contents appropriate for elders. Conclusion: In conclusion, the stage matched exercise intervention program that considered the characteristics of the elders was effective to facilitate exercise behaviors of the elders.

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Structural Behavior of Mixed $LiMn_2O_4-LiNi_{1/3}Co_{1/3}Mn_{1/3}O_2$ Cathode in Li-ion Cells during Electrochemical Cycling

  • 윤원섭;이상우
    • 한국재료학회:학술대회논문집
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    • 한국재료학회 2011년도 춘계학술발표대회
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    • pp.5-5
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    • 2011
  • The research and development of hybrid electric vehicle (HEV), plug-in hybrid electric vehicle (PHEV) and electric vehicle (EV) are intensified due to the energy crisis and environmental concerns. In order to meet the challenging requirements of powering HEV, PHEV and EV, the current lithium battery technology needs to be significantly improved in terms of the cost, safety, power and energy density, as well as the calendar and cycle life. One new technology being developed is the utilization of composite cathode by mixing two different types of insertion compounds [e.g., spinel $LiMn_2O_4$ and layered $LiMO_2$ (M=Ni, Co, and Mn)]. Recently, some studies on mixing two different types of cathode materials to make a composite cathode have been reported, which were aimed at reducing cost and improving self-discharge. Numata et al. reported that when stored in a sealed can together with electrolyte at $80^{\circ}C$ for 10 days, the concentrations of both HF and $Mn^{2+}$ were lower in the can containing $LiMn_2O_4$ blended with $LiNi_{0.8}Co_{0.2}O_2$ than that containing $LiMn_2O_4$ only. That reports clearly showed that this blending technique can prevent the decline in capacity caused by cycling or storage at elevated temperatures. However, not much work has been reported on the charge-discharge characteristics and related structural phase transitions for these composite cathodes. In this presentation, we will report our in situ x-ray diffraction studies on this mixed composite cathode material during charge-discharge cycling. The mixed cathodes were incorporated into in situ XRD cells with a Li foil anode, a Celgard separator, and a 1M $LiPF_6$ electrolyte in a 1 : 1 EC : DMC solvent (LP 30 from EM Industries, Inc.). For in situ XRD cell, Mylar windows were used as has been described in detail elsewhere. All of these in situ XRD spectra were collected on beam line X18A at National Synchrotron Light Source (NSLS) at Brookhaven National Laboratory using two different detectors. One is a conventional scintillation detector with data collection at 0.02 degree in two theta angle for each step. The other is a wide angle position sensitive detector (PSD). The wavelengths used were 1.1950 ${\AA}$ for the scintillation detector and 0.9999 A for the PSD. The newly installed PSD at beam line X18A of NSLS can collect XRD patterns as short as a few minutes covering $90^{\circ}$ of two theta angles simultaneously with good signal to noise ratio. It significantly reduced the data collection time for each scan, giving us a great advantage in studying the phase transition in real time. The two theta angles of all the XRD spectra presented in this paper have been recalculated and converted to corresponding angles for ${\lambda}=1.54\;{\AA}$, which is the wavelength of conventional x-ray tube source with Cu-$k{\alpha}$ radiation, for easy comparison with data in other literatures. The structural changes of the composite cathode made by mixing spinel $LiMn_2O_4$ and layered $Li-Ni_{1/3}Co_{1/3}Mn_{1/3}O_2$ in 1 : 1 wt% in both Li-half and Li-ion cells during charge/discharge are studied by in situ XRD. During the first charge up to ~5.2 V vs. $Li/Li^+$, the in situ XRD spectra for the composite cathode in the Li-half cell track the structural changes of each component. At the early stage of charge, the lithium extraction takes place in the $LiNi_{1/3}Co_{1/3}Mn_{1/3}O_2$ component only. When the cell voltage reaches at ~4.0 V vs. $Li/Li^+$, lithium extraction from the spinel $LiMn_2O_4$ component starts and becomes the major contributor for the cell capacity due to the higher rate capability of $LiMn_2O_4$. When the voltage passed 4.3 V, the major structural changes are from the $LiNi_{1/3}Co_{1/3}Mn_{1/3}O_2$ component, while the $LiMn_2O_4$ component is almost unchanged. In the Li-ion cell using a MCMB anode and a composite cathode cycled between 2.5 V and 4.2 V, the structural changes are dominated by the spinel $LiMn_2O_4$ component, with much less changes in the layered $LiNi_{1/3}Co_{1/3}Mn_{1/3}O_2$ component, comparing with the Li-half cell results. These results give us valuable information about the structural changes relating to the contributions of each individual component to the cell capacity at certain charge/discharge state, which are helpful in designing and optimizing the composite cathode using spinel- and layered-type materials for Li-ion battery research. More detailed discussion will be presented at the meeting.

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유근피로부터 분리한 hederagenin 3-O-b-D-glucopyranosyl(1→3)-a-L-rhamnopyranosyl(1→2)-a-L-arabinopyranoside (HDL)의 항산화 효과 (Antioxidant Effect of Hederagenin 3-O-b-D-Glucopyranosyl(1→3)-a-L-Rhamnopyranosyl(1→2)-a-L-Arabinopyranoside (HDL) Isolated from Root Bark of Ulmus davidiana)

  • 봉진구;박윤엽
    • 생명과학회지
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    • 제20권2호
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    • pp.281-291
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    • 2010
  • 본 연구는 유근피(root bark of Ulmus davidiana)에서 분리한 화합물인 hederagenin 3-O-b-D-glucopyranosyl($1{\rightarrow}3$)-a-L-rhamnopyranosyl($1{\rightarrow}2$)-a-L-arabinopyranoside (HDL)을 이용하여 $CoCl_2$에 의해 생성된 ROS에 대한 항산화 기전을 밝히기 위하여, ROS 생성과 관련된 산화 효소 및 항산화 효소에 대한 저해효과를 조사하였다. 또한 HDL이 $CoCl_2$에 의해 생성된 ROS의 조절을 통해 산화적 스트레스와 관련된 단백질 발현 및 세포주기에 미치는 영향을 조사하였다. 그 결과 HDL은 $CoCl_2$에 의해 유발된 xanthine oxidase와 $H_2O_2$ 생성 증가를 억제하였고, 산화와 관련된 SOD, CAT의 활성을 증가시켜 $H_2O_2$의 가수분해를 촉진하였다. 그리고 HDL은 $CoCl_2$에 의해 유발된 ferritin의 손상과 ferritin iron의 방출을 억제하 였으며, 지질과산화의 증가를 억제하였다. 뿐만 아니라 HDL은 $CoCl_2$에 의해 증가된 G1 phase의 세포를 감소시켰으며, 세포주기와 관련된 p53 및 $p21^{CIP1/WAF1}$의 발현을 감소시켰다. 이러한 연구결과들은 HDL이 천연물로부터 유래한 독성이 없는 항산화제로서의 가능성을 제시한다.

여뀌과 이형경식물의 Dinorphism과 Bisexuality의 변화 (STUDIES ON THE DIMORPHISM AND TRANSITION OF BISEXUALITY OF HETEROSTYLOUS POLYGONACEAE)

  • Harn, Chang-Yawl
    • Journal of Plant Biology
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    • 제3권2호
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    • pp.6-18
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    • 1960
  • The present experiments were designed in order to clarify the differences between the long and short styled plants and the transgressive gradition in the degree of dimorphism among the three heterostylous species of the Polygonus, P. japonica, F. esculentum, and P. senticosa, based on investigations regarding the floral structure, ecological and physiological traits, the results of which are summarized as follows: (1) P. japonica, although it exhibits typical dimorphism, has undergone so high a differentiation between long and short styled that its long styled individuals behave as if they were female; and short styled individuals as if male. In long-styled individuals, filament, anther, and pollen grains show signs of degeneration, most of the pollen being abortive. On the other hand, in short styled individuals, the filament, anther, and pollen grains have attained remarkable development; the pollen grians are large and fertile. In short-plant the fertilized flowers readily drop off in every stage of their embryo development. This species has completely lost the self-fertile property, which is characteristic of the non-dimorphic Polygonum genus. Although this specsei typically exhibits the physiological characteristics of the non-dimorphic Polygonum genus. Although this specisei typically exhibits the physiological characteristics of dimorphism in controlled pollination, the short-styled individuals bear no seed in nature, thus misleading taxonomists to idenfity the short-styled plant as male. 2) The morphological feature of the flower organ of P. senticosa obviously indicates definite dimorphism. Physiologically, however, no differentiation towards dimorphism was observed, the species still retaining, both in long and short-individuals, the self-fertile property common to the Polygonum genus. Elaborate examinations revealed that regardless of the modes of pollination, both fertiization and seed setting flourish, no differentiation betwen legitimate and illegitimate unions being recognizable. This sort of physiological property has not been observed in the investigations of other heterostylous plants. It is assumed that this species is differentiated structurally into dimorphism, but not yet physiologically. In nature, however, this plant would have more opportunities to be cross-pollinated, i.e., legitimately combined, than self-pollinated because of the development of two forms of flowers. 3) In terms of heterostylism, the F. esculentum just occupies the intermediate position between P. japonica and P. senticosa structurally, ecologically, and physiologically. Doescription of some of the physiological behavior of the plant will suffice to demonstrate the above facts. While P. japonica has completely lost its self-fertile property, P. senticosa still retains it wolly. In F. esculentum 2-6% of self-fertility is the result in illegitimate combination. There occur occasionally hereditary self fertile individuals among some of the F. or 20 min. irradiation plot, when they reach any stage of the same bacterial population. In addition to this increase of total population in the plots with the more dose of UV light irradiation, it seems that the more dose of UV light irradiation is the more shortened the generation time of Azotobacter. Therefore, it is clear that variation of reproductive rate must be, mere or less, due to the genetic effects induced by UV light irradiation. On the other hand, the lag phase or logarithmic growth phase in nonirradiated culture is shortened prominently, and this must be due to the difference in bacterial number of the original inoculm. The generation time of Azotobacter is shortened by exogeneous treatment of nuclei acid derivatives, and the degree is greater in case of DNA derivatives than RNA dervatives. W.H. Price reported that the rate of ribose nucleic acid to protein in Staphylococcus muscae is proportional to the generation time: that is the faster the cell can form ribose nucleic acid, the more rapid its growth. This explains the shortening of generation time by exogeneous RNA derivatives in this work reasonably. On the other hand, it is well known that the desoxyribose nuclic acid content per cell is constant and independent of the generation time. A.D. Laren and W.N. Takahashi reported that the infectious RNA from TMV is 6 times as sensitive to inactivation by UV as it is in the form of intact virus, and that inactivation of infectious TMV involves onlu a local change on RNA chain. But, the effect of exogeneous DNA in this work suggests that irradiated living cell which cotain DNA bring about some change on DNA moleculs as well as RNA molecules. And if the mutagenic effects of UV take into consideration, it is very reasonable. Therefore, it is clear that the variation of the generation time by UV irradiation is, more or less, due to the genetic effects. Therefore, it seems that the shortness of the average lifewpan of Azotobacter by UV irradiation is resulted not only from the influence of the environmental conditions, but also from the variation of genetic factor of the individual.

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인체 폐암 세포주 A549에서 Litsea populifolia 추출물의 항산화 및 항암활성 분석 (Anti-oxidative and Anti-cancer Activities of Ethanol Extract of Litsea populifolia)

  • 진수정;오유나;정현영;윤희정;박정하;권현주;김병우
    • 생명과학회지
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    • 제29권6호
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    • pp.679-687
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    • 2019
  • 본 연구에서는 인체 폐암 세포인 A549를 사용하여 Litsea populifolia 에탄올 추출물(EELP)의 항산화 및 항암활성과 그 분자적 기전에 관하여 연구하였다. 먼저 EELP의 DPPH 라디칼 소거활성을 측정한 결과, $IC_{50}$$11.71{\mu}g/ml$로 유의적인 항산화활성을 보였다. 또한 EELP가 인체폐암세포주인 A549와 정상 폐세포인 IMR90의 세포증식에 미치는 영향을 알아본 결과, 정상세포의 생존율에는 거의 영향을 끼치지 않은 반면, EELP 농도의존적으로 A549 세포의 성장이 저해되었으며, 세포 주기 변화를 분석한 결과 EELP에 의해 A549 세포의 강력한 G1 arrest가 유도되는 것을 확인하였다. EELP에 의해 유도되는 G1 arrest는 세포주기 조절 인자인 Cyclin D1, Cyclin E, Cyclin-dependent kinase인 CDK2와 CDK6의 mRNA 발현 감소와 더불어 단백질 발현 감소와 연관되어 있었다. 또한 EELP 처리에 의한 CDK/Cyclin complex의 발현 저해는 DNA 손상에 의해 활성화되는 CHK2의 활성화 형태인 p-CHK2의 발현 증가에 따른 p53 인산화에 따른 활성화와 CDK 활성화 효소인 CDC25A 탈인산화효소의 인산화에 따른 저해에 의해 나타나는 결과로 사료된다. 이러한 결과들로부터 EELP는 두가지 경로인 p53-의존성과 p53-비의존성(ATM/CHK2/CDC25A/CDK2) 경로를 통해 A549의 G1 arrest를 유도하여 세포 증식을 억제하는 것으로 사료된다. 본 연구결과는 EELP가 폐암에 대한 새로운 항암활성 소재로서 사용될 수 있는 가능성을 시사하며, 또한 EELP의 세포주기 조절에 의한 항암기전을 이해하고 향후 지속적 연구를 하는 데 있어서 귀중한 기초자료로 사용될 수 있을 것이다.

Steap4에 의한 지방세포분화 촉진 기전 (Steap4 Stimulates Adipocyte Differentiation through Activation of Mitotic Clonal Expansion and Regulation of Early Adipogenic Factors)

  • 심현아;신주연;김지현;정명호
    • 생명과학회지
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    • 제30권12호
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    • pp.1092-1100
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    • 2020
  • Six-transmembrane epithelial antigen of prostate 4 (Steap4)는 철과 구리를 환원하여 철과 구리의 세포내 유입에 관여하는 금속 환원효소로, 구리 철의 항상성 뿐만 아니라 염증, 포도당 대사, 지질 대사에도 중요한 역할을 한다. 최근에 Steap4가 지방세포의 분화를 촉진한다는 보고가 발표되었으나, 이에 관련된 분자적 기전에 대해서는 알려지지 않았다. 그래서, 본 연구에서는 Steap4에 의한 지방세포분화 촉진에 관련된 기전을 연구하였다. 이를 위해 3T3-L1 백색지방세포, 불멸화된 갈색지방세포(iBA) 및 생쥐의 배아 섬유아 세포인 C3H10T1/3 세포에서 Steap4을 감소시킨 후 지방세포분화 초기단계에 관련된 신호들을 분석하였다. Steap4을 shRNA로 감소시켰을 때 지방세포분화 초기 단계에서 3종류 지방세포의 세포 증식이 억제되었으며, 세포주기 관련 단백질인 cyclin A, cyclin D 그리고 cdk2의 발현은 감소하는 반면 세포주기 저해 단백질인 p21과 p27의 발현은 증가하였다. 또한 세포주기 관련 신호인 p38, ERK 그리고 Akt의 활성화는 억제되었다. 한편 지방세포분화 초기 단계에 관여하는 지방세포분화 전사인자들을 분석하였을 때, Steap4의 감소는 지방세포분화 활성 전사 인자인 C/EBPβ, KLF4의 발현을 저해하는 반면, 지방세포분화 억제 전사 인자인 KLF2, KLF3 그리고 GATA2의 발현은 증가시켰다. 또한 Steap4의 과발현은 C/EBPβ promoter에 존재하는 전사억제 히스톤 표지자인 H3K9me2과 H3K27me3을 감소시켰다. 따라서, 이상의 결과를 종합하면 Steap4는 지방세포분화 초기단계인 mitotic clonal expansion을 촉진하고 지방세포분화 전사인자들의 발현을 조절함으로써, 지방세포분화를 촉진시킴을 알 수 있었다.

일본군 '위안부'의 영화적 기억과 크로노폴리틱스 (Chronopolitics in the Cinematic Representations of "Comfort Women")

  • 박현선
    • 대중서사연구
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    • 제26권1호
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    • pp.175-209
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    • 2020
  • 본 논문은 일본군 '위안부'의 영화적 재현이 어떻게 일상의 영역에서, 그리고 대중의 기억 속에서 '상상력'을 촉발하고 공통의 감각과 정동을 불러일으키는가 살펴보자 한다. 일본군 '위안부' 역사는 오랫동안 망각되었다가 1990년대에 들어서야 공공 기억의 장으로 들어설 수 있었다. 이러한 전환에는 피해자들의 증언과 일본군 '위안부' 문제의 담론화를 가능하게 만든 국내외적 크로노폴리틱스(chronopolitics)가 존재한다. 이는 '시간의 정치학'으로서 일본군 '위안부' 역사의 독특한 위상을 보여주는데, 일본군 '위안부' 문제의 영화적 재현은 역사적 크로노폴리틱스와 연속적이면서도 단절적인 이중성을 보여주며 새로운 시각적 크로노폴리틱스를 드러낸다. 한국영화사의 맥락에서 일본군 '위안부' 재현의 크로노토프는 크게 4가지 국면으로 나누어 생각해 볼 수 있다. 첫째, 1990년대 이전 일본군 '위안부'의 극적 재현들, 둘째, 증언과 역사쓰기로서 1990년대 후반 다큐멘터리, 셋째, 2000년대 들어 멜로드라마적 감수성을 이끌어낸 극영화들, 넷째, 애니메이션 및 기타 장르를 포함하는 매체의 확산이다. 이들 중에서 '위안부' 문제를 대중적 극영화(fiction film)의 범주에서 표상하고 있는 첫 번째 국면과 세 번째 국면에 집중해 논의를 전개하는 것이 이 글의 목적이다. 1990년 이전의 '위안부' 극영화들이 철저히 상업영화와 대중장르의 틀을 고수하며 일본군 '위안부' 역사의 성애화를 추구했다면, 2000년대 이후의 영화들은 대중영화의 양식 속에서 다양한 시도들을 실험해보고 있다. 특히, <귀향>, <아이 캔 스피크>, <허스토리> 등과 같은 2000년대 '위안부' 극영화들의 등장은 우리가 그간 생존자들의 증언과 일본군 '위안부' 운동 등을 통해서 '많이' 알고 있다고 생각했던 이 이슈에 대하여 과연 우리가 '제대로' 알고 있는지, 이에 대한 '문화적 재현은 어떻게 가능한지' 등의 여러 문제를 제기해주고 있다. 일본군 '위안부'를 다룬 2000년대 영화적 재현의 전략들에 주목하면서, 이 글은 멜로드라마의 대중 정치학, 피해자성과 폭력의 재현, 메타기억으로서의 일본군 '위안부' 극영화 등을 논의하고자 한다. 역사적 트라우마에 대한 멜로드라마적 상상이자 메타기억으로서, '위안부' 극영화들은 일본군 '위안부' 문제가 통과해야 할 역사적, 정치적, 미학적 관문들을 보여준다. 보다 구체적으로 말하면, 최근의 극영화들에서 일본군 '위안부' 문제가 한-일 양국 간의 관계를 넘어서, 오래된 식민 구조를 해체하고자 하는 탈식민주의적 과제이자 여성운동과 인권운동이 국제적으로 연대하는 트랜스내셔널한 프로젝트로 거듭나는 방식에 이 글은 주목한다.

서울 석촌동 고분군 출토 기와의 소성온도와 열변형 특성 해석 (Interpretation of Firing Temperature and Thermal Deformation of Roof Tiles from Ancient Tombs of Seokchon-dong in Seoul, Korea)

  • 진홍주;장성윤;이명성
    • 자원환경지질
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    • 제54권6호
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    • pp.671-687
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    • 2021
  • 이 연구에서는 서울 석촌동 고분군 연접적석총에서 출토된 기와의 물리적 및 광물학적 특성을 바탕으로 소성온도를 추정하고, 열변형 과정을 해석하였다. 석촌동 고분군에서는 다량의 기와가 출토되었는데, 일부 기와는 열에 의해 형태가 변하고 불균일한 소성상태를 나타냈다. 원형기와의 표면과 속심의 색조는 비교적 균일한 황갈색 계열로서 약 12% 이상의 높은 흡수율을 나타내며, 미정질 기질에 세립질 석영, 장석류, 운모, 각섬석 등을 포함한다. 또한 미세조직 관찰 결과, 느슨한 기질과 운모의 층상구조가 확인되어 900℃ 이하의 산화환경에서 제작되었을 것으로 추정된다. 반면 열에 변형된 기와는 주로 적갈색과 청회색의 불균일한 표면 색조를 보이며, 단면은 치밀한 적갈색 표면과 다공성의 자회색 내부기질이 함께 나타나는 샌드위치 구조를 나타낸다. 흡수율은 0.8~11%이며, 멀라이트, 헤르시나이트가 동정되어 소성온도가 1,000℃ 이상으로 추정된다. 일부 시료에서는 과소성에 의한 블로우팅 포어(bloating pore)가 관찰되었고, 1,200℃ 이상의 고온을 경험한 것으로 판단된다. 한편, 원형기와를 800~1,200℃ 사이에서 온도별로 재소성하여 물리적 및 광물학적 특성을 확인한 결과, 1,000℃ 부근에서 흡수율이 급격히 낮아지고 고온 광물이 생성되기 시작했다. 또한 점차 온도가 올라갈수록 기질이 부분 용융되고 재결정화되어 변형기와의 열변형 특성과 유사한 결과를 나타냈다. 따라서 석촌동 고분군 기와는 불균일한 소성상태와 1,000~1,200℃에 달하는 2차 고온을 경험하여 형태 변형, 광물 상전이 등의 열변형 특성이 발생하였고, 이는 백제시대 화장의례와 관계가 있는 것으로 생각된다.