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COLOR DIFFERENCES BETWEEN RESIN COMPOSITES BEFORE- AND AFTER-POLYMERIZATION, AND SHADE GUIDES (복합레진의 광중합 전·후와 shade guide의 색차 비교)

  • Chon, Yi-Ju;Cho, Sung-Shik;Um, Chung-Moon
    • Restorative Dentistry and Endodontics
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    • v.24 no.2
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    • pp.299-309
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    • 1999
  • The composite resin, due to its esthetic qualities, is considered the material of choice for restoration of anterior teeth. With respect to shade control, the direct-placement resin composites offer some distinct advantages over indirect restorative procedures. Visible-light-cured (VLC) composites allow dentists to match existing tooth shades or to create new shades and to evaluate them immediately at the time of restoration placement. Optimal intraoral color control can be achieved if optical changes occurring during application are minimized. An ideal VLC composite, then, would be one which is optically stable throughout the polymerization process. The shade guides of the resin composites are generally made of plastic, rather than the actual composite material, and do not accurately depict the true shade, translucency, or opacity of the resin composite after polymerization. So the numerous problems associated with these shade guides lead to varied and sometimes unpredictable results. The aim of this study was to assess the color changes of current resin composite restorative materials which occur as a result of the polymerization process and to compare the color differences between the shade guides provided with the products and the actual resin composites before- and after-polymerization. The results obtained from this investigation should provide the clinician with information which may aid in improved color match of esthetic restoration. Five light activated, resin-based materials (${\AE}$litefil, Amelogen Universal, Spectrum TPH VeridonFil-Photo, and Z100) and shade guides were used in this study. Three specimens of each material and shade combination were made. Each material was condensed inside a 1.5mm thick metal mold with 10mm diameter and pressed between glass plates. Each material was measured immediately before polymerization, and polymerized with Curing Light XL 3000 (3M Dental products, USA) visible light-activation unit for 60 seconds at each side. The specimens were then polished sequentially on wet sandpaper. Shade guides were ground with polishing stones and rubber points (Shofu) to a thickness of approximately 1.5mm. Color characteristics were performed with a spectrophotometer (CM-3500d, Minolta Co., LTD). A computer-controlled spectrophotometer was used to determine CIELAB coordinates ($L^*$, $a^*$ and $b^*$) of each specimen and shade guide. The CIELAB measurements made it possible to evaluate the amount of the color difference values (${\Delta}E{^*}ab$) of resin composites before the polymerization process and shade guides using the post-polishing color of the composite as a control, CIE standard D65 was used as the light source. The results were as follows. 1. Each of the resin composites evaluated showed significant color changes during light-curing process. All the resin composites evaluated except all the tested shades of 2100 showed unacceptable level of color changes (${\Delta}E{^*}ab$ greater than 3.3) between pre-polymerization and post-polishing state. 2. Color differences between most of the resin composites tested and their corresponding shade guides were acceptable but those between C2 shade of ${\AE}$litefil and IE shade of Amelogen Universal and their respective shade guides exceeded what is acceptable. 3. Comparison of the mean ${\Delta}E{^*}ab$ values of materials revealed that Z100 showed the least overall color change between pre-polymerization and post-polishing state followed by ${\AE}$litefil, VeridonFil-Photo, Spectrum TPH, and Amelogen Universal in the order of increasing change and Amelogen Universal. Spectrum TPH, 2100, VeridonFil-Photo and ${\AE}$litefil for the color differences between actual resin and shade guide. 4. In the clinical environment, the shade guide is the better choice than the shade of the actual resin before polymerization when matching colors. But, it is recommended that custom shade guides be made from resin material itself for better color matching.

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A Study on the Archival Basis of History by Simaqian and Herodotus (『사기』와 『역사』에 담긴 기록학의 기초 역사-인간[Homo Historicus], 사마천과 헤로도토스)

  • Oh, Hang Nyeong
    • The Korean Journal of Archival Studies
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    • no.65
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    • pp.365-396
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    • 2020
  • I examined the archival basis of two historians who wrote history books with the same title of 'History'; Simaqian of ancient China and Herodotus of Halikarnassos. I examined a prejudice to these two history books, a misunderstanding of them as an imagination rather than a history. How can an imagination become a history? First, I explained the common characteristics found in their compilation and writing of 'History.' Simaqian and Herodotus did their field-works in historical sites, gathered oral-histories, and arranged archives they collected. These two historians heavily engaged in archival works in terms of verifying authenticity and reliability of their sources on the basis of historical empiricism. There are some misunderstanding on their archival endeavor and on the very nature of archives and historical studies as empirical studies. Furthermore, this misunderstanding regarding them as literature came from a confusion over the concept of literature. The creativity of literature is not equal to the "fictitiousness" of history despite historical works sometimes may give us an impression by the way of describing and providing insight into a certain event(s) and a person(s). As Herodotus said, a recognition of the differences of each race and human is a departure of historical archiving of the valuable experiences of human-beings. By doing so, natural results of archival behaviors, preservation of the records, and consistent inquiry of historian-archivists become a humanistic passage overcoming the current wrong trends of historical studies confined to a narrow nation-history.

Analysis of Annual Variability of Landfast Sea Ice near Jangbogo Antarctic Station Using InSAR Coherence Images (InSAR 긴밀도 영상을 이용한 남극 장보고기지 인근 정착해빙의 연간 변화 분석)

  • Han, Hyangsun;Kim, Yeonchun;Jin, Hyorim;Lee, Hoonyol
    • Korean Journal of Remote Sensing
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    • v.31 no.6
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    • pp.501-512
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    • 2015
  • Landfast sea ice (LFI) in Terra Nova Bay, East Antarctica where the Jangbogo Antarctic Research Station is located, has significant influences on marine ecosystem and the sailing of an icebreaker. Therefore, it is essential to analyze the spatio-temporal variation of the LFI in Terra Nova Bay. In this study, we chose interferometric pairs with the temporal baseline from 1 to 9 days out of a total of 62 COSMO-SkyMed synthetic aperture radar (SAR) images over Terra Nova Bay obtained from December 2010 to January 2012, and then constructed the coherence image of each pair. The LFI showed coherence values higher than 0.3 even in the interferometric SAR (InSAR) pairs of up to 9-days of temporal baseline. This was because the LFI was fixed at coastline and thus showed low temporal phase decorrelation. Based on the characteristics of the coherence on LFI, We defined the areas of LFI that show spatially homogeneous coherence values higher than 0.5. Pack ice (PI) and open water showed low coherence values due to large temporal phase decorreation caused by current and wind. Distinguishing PI from open water in the coherence images was difficult due to their similarly low coherence values. PI was identified in SAR amplitude images by investigating cracks on the ice. The extents of the LFI and PI were estimated from the coherence and SAR amplitude images and their temporal variations were analyzed. The extent of the LFI increased from March to July (maximum extent of $170.7km^2$) and decreased from October. The extent of the PI increased from February to May and decreased from May to July when the LFI increases dramatically. The extent of the LFI and air temperature showed an inverse correlation with a time lag of about 2 months, i.e., the extent of the LFI decreases after 2 months of the increase in the air temperature. Meanwhile the correlation between wind speed and the extent of the LFI was very low. This represents that the extent of LFI in Terra Nova Bay are influenced more by the air temperature than wind speed.

Wind-and Rain-induced Variations of Water Column Structures and Dispersal Pattern of Suspended Particulate Matter (SPM) in Marian Cove, the South Shetland Islands, West Antarctica during the Austral Summer 2000 (서남극 남 쉐틀랜드 군도 마리안 소만에서 바람 및 강수에 의한 여름철 수층 구조의 변화와 부유물질 분산)

  • 유규철;윤호일;오재경;강천윤;김예동;배성호
    • The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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    • v.8 no.4
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    • pp.357-368
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    • 2003
  • Time-series CTDT (Conductivity/Temperature/Depth/Transmissivity) were obtained at one point near tidewater glacier of Marian Cove (King George Islands, Antarctica) to present water column properties and SPM (suspended particulate matter) dispersal pattern in relation with tide, current, meteorological data, and SPM concentration. Four layers were divided from the water column characteristics measured in the interval of an hour for about 2 days: 1) cold, fresh, and turbid surface mixed layer between 0-20 m in water depth, 2) warm, saline, and relatively clean Maxwell Bay inflow between 20-40 m in water depth, 3) turbid/cold tongue of subglacial discharges compared with the ambient waters between 40-70 m in water depth, and 4) cold, saline, and clean bottom water beneath 70 m in water depth. Surface plume, turbid freshwater at coastal/cliff area in late summer (early February), had the characteristic temperature and SPM concentration according to morphology, glacial condition, and composition of sediments. The restrict dispersion only over the input source of meltwater discharges was due to calm wether condition. Due to strong wind-induced surface turbulence, fresh and turbid surface plume, englacial upwelling cold water, glacier-contact meltwater, and Maxwell Bay inflow was mixing at ice-proximal zone and the consequent mixed layer deepened at the surface. Large amount of precipitation, the major controlling factor for increasing short-term glacial discharges, was accompanied by the apparent development of subglacial discharge that resulted in the rapid drop of salinity below the mid depth. Although amount of subglacial discharge and englacial upwelling may be large, however, their low SPM concentration would have small influence on bottom deposition of terrigenous sediments.

Analysis of Climate Change Adaptation Researches Related to Health in South Korea (한국의 건강 분야 기후변화적응 연구동향 분석)

  • Ha, Jongsik
    • Journal of Climate Change Research
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    • v.5 no.2
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    • pp.139-151
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    • 2014
  • It is increasingly supported by scientific evidence that greenhouse gas caused by human activities is changing the global climate. In particular, the changing climate has affected human health, directly or indirectly, and its adverse impacts are estimated to increase in the future. In response, many countries have established and implemented a variety of mitigation and adaptation measures. However, it is significant to note that climate change will continue over the next few centuries and its impacts on human health should be tackled urgently. The purpose of this paper is to examine domestic policies and research in health sector in adaptation to climate change. It further aims to recommend future research directions for enhanced response to climate change in public health sector, by reviewing a series of adaptation policies in the selected countries and taking into account the general features of health adaptation policies. In this regard, this study first evaluates the current adaptation policies in public health sector by examining the National Climate Change Adaptation Master Plan(2011~2015) and Comprehensive Plan for Environment and Health(2011~2020) and reviewing research to date of the government and relevant institutions. For the literature review, two information service systems are used: namely, the National Science and Technology Information Service(NTIS) and the Policy Research Information Service & Management(PRISM). Secondly, a series of foreign adaptation policies are selected based on the global research priorities set by WHO (2009) and reviewed in order to draw implications for domestic research. Finally, the barriers or constraints in establishing and implementing health adaptation policies are analyzed qualitatively, considering the general characteristics of adaptation in the health sector to climate change, which include uncertainty, finance, technology, institutions, and public awareness. This study provides four major recommendations: to mainstream health sector in the field of adaptation policy and research; to integrate cross-sectoral adaptation measures with an aim to the improvement of health and well-being of the society; to enhance the adaptation measures based on evidence and cost-effectiveness analysis; and to facilitate systemization in health adaptation through setting the key players and the agenda.

Spatial and Temporal Variation of Phytoplankton Community in the Coastal Waters of Jeju Island (제주연안 식물플랑크톤 군집의 시공간적 변화)

  • KIM, GYU-BEOM;KANG, SU-MIN;LEE, JOON-BAEK
    • The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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    • v.24 no.1
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    • pp.92-105
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    • 2019
  • Spatial and temporal characteristics of phytoplankton communities around the coastal waters of Jeju Island were investigated with environmental factors such as water temperature, salinity, and dissolved oxygen. Monthly samples were collected at 0 and 30 m depths of 10 stations from March 2015 to February 2016. During the survey period, water temperature ranged in 13.7~25.9 and $13.6{\sim}20.8^{\circ}C$ at 0 and 30 m, salinity in 31.51~34.47 and 33.03~34.47 psu at 0 and 30 m, and dissolved oxygen in 6.12~8.10 and $5.73{\sim}7.88mg\;L^{-1}$ at 0 and 30 m, respectively. Chlorophyll-a ranged in 0.28~2.48 and $0.44{\sim}1.01{\mu}g\;L^{-1}$ at 0 and 30 m, respectively. Phytoplankton abundance fluctuated in the range of $5,300{\sim}639,900cells\;L^{-1}$ during the year, showing the lowest in February at all stations, and the highest in July at the northern and western sea as well as in August at the southern and eastern sea of Jeju Island. A total of 362 species were occurred including 181 spp. of Bacillariophyta, 147 spp. of Dinophyta and 34 spp. of other phytoflagellates. Dominant species with occupancy rate over 20 percent of phytoplankton abundance showed apparent seasonal succession such as Paralia sulcata and Skeletonema costatum in spring and autumn, 6 spp. of genus Chaetoceros in summer, and 2 spp. of genus Chaetoceros and Thalassionema frauenfeldii in winter. Monthly abundance in the northern and western sea fluctuated with similar tendency, and the southern and eastern sea also showed similar pattern of monthly abundance variation. Species composition and dominant species succession mentioned above were quite different from previous studies, so some physical changes such as water temperature, salinity and current pattern might cause the changes of phytoplankton assemblages around Jeju Island.

Investigation on the Awareness and Preference for Wood Culture to Promote the Value of Wood: I. Awareness of Wood and Cultural Experience (목재의 가치증진을 위한 목재문화에 대한 인식 및 선호도 조사: I. 목재와 문화체험에 대한 인식)

  • HAN, Yeonjung;LEE, Sang-Min
    • Journal of the Korean Wood Science and Technology
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    • v.49 no.6
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    • pp.616-642
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    • 2021
  • Improving public awareness of wood is essential for achieving the goal of establishing wood culture by expanding the use of wood. This study presents a basic examination of the strategy of revitalizing wood culture and a survey of its current status and requirements. The survey was divided into seven categories: awareness of wood culture; use characteristics of wood culture; preference and demand for wood culture; awareness of sub-fields of wood culture; awareness of the cultural resources of wood; trends of wood utilization; and wood-related living environment. Based on the survey results, the study analyzed four items: awareness of wood and cultural experience; awareness of the cultural resources of wood; wood-related living environment and trends of wood utilization; and preference and demand for wood culture. In this study, the public awareness of wood and cultural experiences, the first of four items, was analyzed using the survey results. Generally, wood and wood culture are viewed as materials and a cultural heritage, respectively. Moreover, wood is ecofriendly. However, no substantial difference was observed between the two perceptions. Forty-five percent of the respondents reported that using wood exerts a positive effect on the body and mind. However, such use also destroys forests. Additionally, the recognition of wood-related workers, such as engineers or skilled workers, was relatively low compared with educators, such as wood education experts. Moreover, less than 50% of the respondents answered that major projects related to wood culture are well-known, whereas 30% participated in wood education, such as woodworking experience, where the majority required hand tools. Furniture, wooden accessories, and wooden buildings were among the objects that individuals intended to make through the wood culture program. Approximately 23% of the respondents were aware about the wood culture experience center, while approximately 50% had visited it. The response rate to woodworking technology was 73%, where the highest response was found for wood education experts. To improve public awareness about wood, the importance of entertainment factors over educational factors should be considered in the experience of individuals. To provide opportunities to experience wood culture for more individuals, developing and actively promoting various contents, including entertainment elements, are necessary.

Characteristics and Significance of the Huirang Daesa Sculpture at Haeinsa Temple in Hapcheon (합천(陜川) 해인사(海印寺) 희랑대사상(希朗大師像)의 특징과 제작 의미)

  • Jeong, Eunwoo
    • MISULJARYO - National Museum of Korea Art Journal
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    • v.98
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    • pp.54-77
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    • 2020
  • Produced during the Goryeo period (718-1392), the statue of the monk Huirang Daesa at Haeinsa Temple in Hapcheon is almost life-size, with a height of 82.4 cm, a width of 66.6 cm at the knees, and a maximum width of 44 cm at the torso (front and back). Notably, it is the only known example of an East Asian Buddhist sculpture made from wood and dry lacquer that was formed by joining the front and back halves. However, a similar technique was used on a dry lacquer statue of the Medicine Buddha at Cheongnyangsa Temple in Bonghwa, which is estimated to date from the late Goryeo or early Joseon period. As such, this technique is thought to represent this particular time period. In an eighteenth-century travelogue about a trip to Mt. Gayasan, the author describes a sculpture that is believed to be the statue of Huirang Daesa at Haeinsa Temple, based on various unique features that closely correspond to the sculpture's current appearance. For example, the sculpture is said to have a hole in the chest and rough, knobby tendons and bones, two features that can still be seen today. Another sculpture of a Buddhist monk who was active in the western regions during the third and fourth century also has a hole in the chest, which is said to be a symbol of spiritual strength. The travelogue also states that the statue was lacquered black at the time, which means that it must have been painted with its present colors some time in the nineteenth century. Over time, the sculpture has been enshrined in various halls of Haeinsa Temple, including Haehaengdang, Jinsangjeon, and later Josajeon (Hall of the Patriarchs), and Bojangjeon. Records show that images of Buddhist monks, or "seungsang," were produced in Korea as early as the Three Kingdoms period (18 BCE-660 CE), but few of these works have survived. At present, only four such sculptures are extant, including the images of Huirang Daesa from the Goryeo period, and those of Monk Naong and Uisang Daesa from the Joseon period. Of these, the sculpture of Huirang Daesa has special significance for its early production date (i.e., CE. tenth century), outstanding production techniques, and superb artistic quality, realistically capturing both the external appearance and internal character of the subject. The tradition of producing, sanctifying, and worshipping statues of monks was prevalent not only in Korea, but also in China and Japan. However, each country developed its own preferred materials and techniques for producing these unique images. For example, while China has a large number of mummified Buddhist images (yuksinbul), Japan produced diverse images with various materials (e.g., dry lacquer, wood, clay) according to period. But despite the differences in materials and techniques, the three nations shared the same fundamental purpose of expressing and honoring the inherent spirituality of the monks.

International Research Trends Related to Inquiry in Science Education: Perception and Perspective on Inquiry, Support and Strategy for Inquiry, and Teacher Professional Development for Inquiry (과학교육에서 탐구 관련 국외 연구 동향 -탐구의 인식과 관점, 전략과 지원, 교사 전문성의 관점에서-)

  • Yu, Eun-Jeong;Byun, Taejin;Baek, Jongho;Shim, Hyeon-Pyo;Ryu, Kumbok;Lee, Dongwon
    • Journal of The Korean Association For Science Education
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    • v.41 no.1
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    • pp.33-46
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    • 2021
  • Inquiry occupies an important place in science education, and research related to inquiry is widely conducted. However, due to the inclusiveness of the concept of "exploration," each researcher perceives its meaning differently, and approaches may vary. In addition, criticisms have been raised that the results of classes using inquiry in science education do not guarantee meaningful changes to students. Therefore, this study attempts to identify the trend of SSCI-level research papers dealing with inquiry in science education over the past three years to confirm the current status and effectiveness of the inquiry. Researches used in the analysis are International Journal of Science Education, Journal of Research in Science Teaching, Research in Science Education, and Science Education, and limited to those that directly suggest "inquiry (enquiry)" as a keyword. Based on extracted 75 papers, the classification process was conducted, and an analysis frame was derived inductively by reflecting the subject and characteristics. Specific cases for each category were presented by dividing into three aspects: perception and perspective on inquiry, support and strategy for inquiry, and teacher professional development for inquiry. The results of examining the implications for scientific inquiry are as follows: First, rather than defining inquiry as an implicit proposition or presenting it as a step-by-step procedure, it was induced to grasp the meaning of inquiry more comprehensively and holistically. Second, as to whether the inquiry-based instruction is effective in all aspects of the cognitive, functional, and affective domains of science, the limitations are clearly presented, and the context-dependent and subject-specific properties and limitations of inquiry are emphasized. Third, uncertainty in science inquiry-based instruction can help learners to begin their inquiry and develop interest, but in the process of recognizing data and restructuring knowledge, explicit and specific guidance and scaffolding should be provided at an appropriate timing.

A Study on the Development of Environment Color Checklists for Senior Center Based on Characteristics of the elders (재가노인의 특성을 고려한 경로당 환경색채 체크리스트 개발)

  • Choi, Yerim;Park, Heykyung
    • Korea Science and Art Forum
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    • v.34
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    • pp.327-337
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    • 2018
  • Korea is rapidly becoming an aging society as much as it takes the first place among OECD countries, and as the life expectancy of Korea gradually increases, the proportion of the elders in society increases. Accordingly, the happiness of the elders is contributed to the overall social atmosphere and happiness, however, the lower quality of life of the elders due to physical, psychological and social changes can be developed into social problems such as depression and rising suicide rate. As a result, there is a social interest in improving the quality of life and satisfaction of the elders, and the senior citizen center is receiving renewed attention as a form of welfare facility that can play a pivotal role in the social activities of the elders. In recent years, efforts to improve the environment of the senior citizen center have been made due to the growing role of it, however, there is a controversy over whether the quality of the indoor environment is user-friendly or not due to the limitations of material resources and human resources. It is considered that the quality of the color environment should be improved in the senior citizen center in the way that the color environment is not only an indoor environmental factor which gives high psychological and mental effects to users but also a way to improve the environmental satisfaction at the lowest cost. Previous studies on the facilities related to the elders have been actively carried out, but they were very sporadic and there was very little information about the color environment in the related laws or in the guideline presented by cities. It is necessary to integrate guidelines that are scattered within a comprehensive range without any specific target in order to grasp the current status of the color environment and to properly evaluate it. In addition, considering that the senior citizen center is an important leisure facility for the elders that functions in a residential area with a nationwide network, the results of this study are expected to contribute to the environmental improvement of existing senior citizen center which will be activated in the future by enabling the improvement of psychological satisfaction of the elders.