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Slant Shear Test for Determining the Interfacial Shear Strength of Concrete Strengthened with Ultra-High Performance Fiber Reinforced Concrete (초고성능 섬유보강 콘크리트로 보강된 콘크리트의 계면 전단강도 결정을 위한 경사전단 실험)

  • Lim, Woo-Young;Hong, Sung-Gul
    • Journal of the Korea Concrete Institute
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    • v.28 no.6
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    • pp.637-646
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    • 2016
  • In this study, slant shear tests for the prism specimens strengthened with ultra-high performance fiber reinforced concrete (UHPFRC), normal- and high-strength concrete were performed to evaluate the interfacial shear strength between old and new concrete substrate. Test parameters are the roughness of surface, concrete strength, and fiber volume fraction of UHPFRC. The surface of the concrete was roughened by shot blasting. Test results showed that the adhesion bond resistance of the specimen with a roughened surface was very large compared to that of the specimen with a smooth surface. In addition, the interfacial shear strength appeared to be affected by the concrete strength rather than the fiber volume fraction. For the roughened surface by shot-blasting method, interfacial shear resistance exceeded the upper limit which is presented in current design codes even if the shear-friction reinforcements are not provided. Based on the test results, it is applicable to use the current concrete design codes to achieve the shear-friction design for the interface between conventional concrete and UHPFRC. However, for the surface which is not processed, it would be appropriate to provide additional shear-friction reinforcement.

A Study on the History of Geography in China: 1909~1978 (학회.학과.연구소를 중심으로 본 중국지리학사: 1909~1978)

  • Lee, Kang-Won
    • Journal of the Korean Geographical Society
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    • v.48 no.3
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    • pp.417-432
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    • 2013
  • The purpose of this paper is to investigate the history of geography in China from 1909 when the Chinese Geographical Society(zhonguo dixuehui) was established to 1978 when the reform and open policy was initiated. The investigation was done with an emphasis on the history of institutions like academic societies, university departments and institutes. Before the PRC's establishment, the Chinese Geographical Society, the Chinese Historical Geography Society(yugong xuehui) and the Geographical Society of China(zhongguo dili xuehui) were established. After the PRC's establishment, however, the academic societies were merged together. The first university department of geography was that of Dongnan university(Nanjing university) established by Zu Kezhen in 1921. Since that Zhongshan university, Zhejiang university, Qinghua university, Beijing normal university and Beijing university established the geography departments. In 1950s the academic societies and university departments experienced the restructuring of organization and the Institute of Geography in Chinese Academy of Science was established. At that time the task of geography imposed by PRC was to serve to agricultural production and to introduce advanced Soviet science. From the beginning of the Cultural Revolution in 1966 to the eve of reform and open policy in 1978, the geography in China has experienced some deep recession. The reform and open policy was a new opportunity and crisis to geographers in China.

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Effects of Long-Term High-Fat Diet Feeding on Gene Expression of Inflammatory Cytokines in Mouse Adipose Tissue

  • Oh, Nu-Ri;Hwang, Ae-Rang;Jeong, Ja-In;Park, Sung-Hyun;Yang, Jin-Seok;Lee, Yong-Ho
    • Biomedical Science Letters
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    • v.18 no.1
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    • pp.56-62
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    • 2012
  • This study was to investigate the effects of high-fat diet feeding for a very long period of time on gene expression of inflammatory cytokines in mouse adipose tissue and to determine whether caloric restriction (CR) or insulin sensitizer treatment changes the cytokine gene expressions even in obese mice fed a high-fat diet for a very long term-period. Gene expression levels of tumor necrosis factor-${\alpha}$ (TNF-${\alpha}$), interleukin-6 (IL-6), and monocyte chemoattractant protein-1 (MCP-1) were examined by real-time PCR in subcutaneous abdominal adipose tissue (SubQ) from obese and non-obese male C57BL/6 mice at 16, 26, 36, 47, and 77 weeks of age on either normal diet (ND) or high-fat diet (HFD) after starting at 6 weeks of age. In addition, gene expression levels of TNF-${\alpha}$, IL-6 and MCP-1 were determined in SubQ before and after rosiglitazone treatment or CR on 47-week-old obese mice. The results demonstrated that gene expression levels of TNF-${\alpha}$, IL-6 and MCP-1 were significantly increased with aging in SubQ of mice in both groups of diet. MCP-1 gene expression of SubQ in all ages tested was significantly or marginally increased in mice on HFD compared with ND. While TNF-${\alpha}$ expression was significantly reduced by rosiglitazone, IL-6 and MCP-1 were significantly decreased by CR. The basic data in this study will be useful for characterizing the C57BL/6 mouse as an animal model of obesity induced by high-fat diet feeding for a very long period of time, and a better understanding of inflammatory cytokine regulation in diet induced obesity which may facilitate the development of new therapeutic strategies to prevent the complications of obesity.

Diversity and origin of bottle gourd, Lagenaria

  • Yuasa, Hiroshi
    • Proceedings of the Plant Resources Society of Korea Conference
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    • 2002.11a
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    • pp.96-97
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    • 2002
  • Bottle gourd, Lagenaria siceraria, is one of the oldest cultivated plants. To bigin with, its fruit was used as a complete liquid bottle or container. It was a very widespread cultivated plant in prehistoric times, for example (there) is a report from Peru as early as between 13,000 B.C and 11,000 B.C. The dug-out finds in Japan proved to be about 95,000 years old according to the /sup 14/C analysis. The bottle grourd was the most important plant before the invention of pottery in many areas of Asia, New Guinea, Polynesia, America, and Africa. I would like to suggest that there should be "The Bottle Gourd Age" prior to the Pottery Age. Bottle gourds are also used for various purposes such as food, masks, pipes, musical instruments, medicine, symbols, artistic products and also as penis-sheaths of men's attire. Their purposes number more than 220 including 70 varienties of containers or bottles. I consider that its utilization should be called a culture, as it were, "The gourd culture." The shape and the size of the fruit of bottle gourd have a larger variety than those of any other plant. As for the size, it is reported that they range from those that are shorter than 3cm to those that are ovoid and longer than 60cm in diameter. With regard to the shape of its fruit, the bottle gourd can be classified into 7 groups and even more than 30 races, considering the difference of the size. The seeds are so variable without two horn-like projections, with smooth surface or longitudinalines, white or brown, with smooth corky margin. Generally, it seems that there is no correlation between seem shape and fruit shape. My study shows that the seeds of gourd. My study shows that the seeds of gourd in Asia are so simple in shape and in color except for the size. But the seeds of those in Africa are various and seem to be beyond the confines. Explaining the great diversity of the seeds of those in Africa therefore, they appear to have no correlation among the types of fruit of the bottle gourd with African origin. It might be supposed that another 4 wild Lagenaria spp. distribute only in Africa. The intraspecies hybrid is confirmed between the bottle gourd, Lagenaria siceraria, and wild L. spehaerica. And Fl hybrid is sterile: it has no fertility. However, even though the shapes of the fruit and the seeds are different, they can cross with each other. Moreover, their hybrids grow up to be extremely vigorous and have normal fertility. Fruit shapes of Fl plants are similar to those of their parents, if they have the same character. Whereas, the fruit shape often became different from each other when the cross occurs between those with different fruit shapes. It is shown that dumbbell shapes, HYOTAN in Japanese, is recessive while its bitterness is dominant. Thus the character of F2 hybrids Is segregative. I'll give further particulars of the heredity of the groud in my lecture.

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AN EXPERIMENTAL STUDY OF $GUIDOR^{(R)}$ BARRIER MEMBRANE ABOUT BONE PROMOTION AROUND DENTAL IMPLANTS PLACED INTO EXTRACTION SOCKET IN DOGS (성견의 Implant 주위에 $GUIDOR^{(R)}$ BARRIER MEMBRANE 사용후 골신생에 관한 실험적 연구)

  • Yang, Myeong-Cheol;Jin, Woo-Jeong;Shin, Hyo-Keun;Kim, Oh-Hwan
    • Maxillofacial Plastic and Reconstructive Surgery
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    • v.18 no.1
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    • pp.135-143
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    • 1996
  • The aim of this study was to evaluate bone promotion of bioreabsorbable guided tissue regeneration for generating new bone adjacent to osseointegrated implants in dogs. Third premolars were extracted in dgo mandibles. Cylindrical HA-coated implants were placed into extracted sockets in dogs. And test sites were protected by $GUIDOR^{(R)}$ matrix barrier. But control sites were not protected by membrances. The sites were examined clinically, radiologically, and histologically after 1, 2, and 4 months to assess bone regeneration. The results obtained were as foolows : 1. There were the good healing and the stability of $GUIDOR^{(R)}$ matrix barrier in experimental site during the healing period. 2. Complete resorption of $GUIDOR^{(R)}$ matrix barrier was clinically observed about 4 months postoperatively. 3. The woven bone changed to mature bone with a normal cortical plate and mature, resting periosteum after 4 months. 4. In experimental site, there was a significantly greater bone promtion than observed in control site. 5. $GUIDOR^{(R)}$ matrix barrier was useful for the preparation of immediate dental implants.

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Regenerative effect of recombinant human bone morphogenetic protein-2/absorbable collagen sponge (rhBMP-2/ACS) after sequestrectomy of medication-related osteonecrosis of the jaw (MRONJ)

  • Min, Song-Hee;Kang, No-Eul;Song, Seung-Il;Lee, Jeong-Keun
    • Journal of the Korean Association of Oral and Maxillofacial Surgeons
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    • v.46 no.3
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    • pp.191-196
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    • 2020
  • Objectives: Beyond the original application approved by the U.S. Food and Drug Administration, recombinant human bone morphogenetic protein-2 (rhBMP-2) is used for medication-related osteonecrosis of the jaw (MRONJ) treatment because of its bone remodeling enhancement properties. The purpose of the study was to investigate the bone formation effect of rhBMP-2/absorbable collagen sponge (ACS) in patients with MRONJ. Materials and Methods: In this retrospective cohort study, 26 female patients diagnosed with MRONJ and who underwent mandibular sequestrectomy at Ajou University Dental Hospital from 2010 to 2018 were included. The experimental group was composed of 18 patients who received rhBMP-2/ACS after sequestrectomy, while the control group was composed of 8 patients who did not receive rhBMP-2/ACS after sequestrectomy. A total dose of 0.5 mg of rhBMP-2 was used in the experimental group at a concentration of 0.5 mg/mL. Follow-up panoramic X-rays were taken immediately after the surgery and more than 6 months after the surgery. Using those X-rays, a radiographic index of bone defect area was calculated using the modified Ihan Hren method, which measures radiographic density of the normal bone and the defect site. Results: This study suggests that rhBMP-2 contributes to new bone formation. The mean radiographic index immediately after surgery and more than 6 months after the surgery for the experimental group was 68.4% and 79.8%, respectively. The mean radiographic index immediately after surgery and more than 6 months after the surgery for the control group was 73.4% and 76.7%, respectively (Wilcoxon signed rank test, P>0.05). The mean radiographic index increased 11.4% in the experimental group and 3.27% in the control group (Mann-Whitney U-test, P<0.05). Conclusion: Based on the results, use of rhBMP-2/ACS on bone defect sites after sequestrectomy could be a successful strategy for treatment of MRONJ patients.

A Study of Effective Power Management for Infrafree Variable Message Sign (인프라 독립형 가변안내표지판의 효율적 전력 운영 방안 연구)

  • Lim, Se-Mi;Lee, Ji-Hoon;Park, Jun-Seok;Kim, Byung-Jong;Kim, Won-Kyu;Son, Seung-Neo
    • The Journal of The Korea Institute of Intelligent Transport Systems
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    • v.10 no.6
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    • pp.53-62
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    • 2011
  • Although the demand of Variable Message Sign(VMS) has become pervasive in fulfilling the ITS policy, there are still several unsolved problematic issues. The most critical ones of them are inequality and inefficiency of providing traffic information. This paper proposes the Infra-free Variable Message Sign in order to provide useful informations such as road condition, weather, and traffic of the area, where constructing the infrastructure of communication and power supply is relatively very hard. First of all, the characteristics of infra-free Variable Message Sign are studied and analyzed in deep because of differences between normal Variable Message Sign and Infra-free Variable Message Sign in the configuration and the operating method due to the nature of the Infra-free Variable Message Sign. Futhermore, for effective power management of operating Infra-free Variable Message Sign with limited power acquired through stand-alone PV system, new battery connection structure and dynamically variable power managements for the differently shown messages on Variable Message Sign are proposed. The proposed structure in this paper can be applied to not only power management for Infra-free Variable Message Sign but also power management for the various applications using parallel connection battery system.

Physical and Mechanical Properties of Synthetic Lightweight Aggregate Concrete (인공경량골재(人工輕量骨材) 콘크리트 물리(物理)·역학적(力學的) 특성(特性))

  • Kim, Seong Wan;Min, Jeong Ki;Sung, Chan Yong
    • Korean Journal of Agricultural Science
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    • v.24 no.2
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    • pp.182-193
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    • 1997
  • The normal cement concrete is widely used material to build the construction recently, but it has a fault to increase the dead load on account of its unit weight is large compared with strength. Therefore, many engineers are continuously searching for new materials of construction to provide greater performance at lower density. The main purpose of the work described in this paper were to establish the physical and mechanical properties of synthetic lightweight aggregate concrete using perlite on fine aggregate and expanded clay, pumice stone on coarse aggregate. The test results of this study are summarized that the water-cement ratio was shown 47% using expanded clay, 56% using pumice stone on coarse aggregate, unit weight was shown $l,622kgf/m^3$ using expanded clay, $l,596kgf/m^3$ using pumice stone on coarse aggregate, and the absorption ratio was shown same as 17%. The compressive strength was shown more than $228kgf/cm^2$, tensile and bending strength was more than $27kgf/cm^2$, $58kgf/cm^2$ at all types, and rebound number with schmidt hammer was increased with increase of compressive strength. The static modulus was $1.12{\times}10^5kgf/cm^2$ using expanded clay, $1.09{\times}10^5kgf/cm^2$ using pumice stone on coarse aggregate, and stress-strain curves were shown that increased with increase of stress, and the strain on the maximum stress was shown identical with $2.0{\times}10^{-3}$, approximately.

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Investigation of 'First-Night Effect' in Normal Young Adult Male Subjects on Polysomnography (젊은 정상인 남자에서 수면다원기록상의 '첫날밤 효과' 분석)

  • Kim, Eui-Joong;Jeong, Do-Un
    • Sleep Medicine and Psychophysiology
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    • v.5 no.1
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    • pp.111-117
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    • 1998
  • Objectives : 'First-night effect' has been a well-known concept since 1960's. It is important because it is one of the major factors to be considered in assessing the reliability of polysomnographic data. However, 'reverse first-night effect' has also been described, resulting in the inconsistency of conceptualization. We attempted to investigate on the first-night effect in adults by having each of them take two nights of polysomnography in a controlled environment. Young healthy adult volunteers were chosen as subjects in order to rule out age- or health-related confounders. Methods : Polysomnography was performed on eight male medical students (mean $age=23.5\;{\pm}\;0.9$) for two nights with Grass model 78 polysomnograph. We scored manually under the standard protocol each epoch of the sleep records. Sleep variables were obtained and compared between the two nights. Results : Sleep period time(SPT) and total sleep time(TST) of the third fraction of night were significantly longer on the first night than on the second night (p<0.05). However, other sleep variables such as percentage of each sleep stage, sleep latency, REM sleep latency, number of waking, and sleep efficiency were not different between the two nights. Conclusion : We could not confirm the existence of first-night effect in this study. In healthy young male adults, it may not happen at all or may happen to a very negligible degree. Young healthy adults may have more adaptability to a new sleep environment. Also, the provision of a reasonably comfortable sleep environment could have helped them with abolition of first-night effect.

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LATEST RESULTS OF THE MAXI MISSION

  • MIHARA, TATEHIRO
    • Publications of The Korean Astronomical Society
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    • v.30 no.2
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    • pp.559-563
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    • 2015
  • Monitor of All-sky X-ray Image (MAXI) is a Japanese X-ray all-sky surveyer mounted on the International Space Station (ISS). It has been scanning the whole sky since 2009 during every 92-minute ISS rotation. X-ray transients are quickly found by the real-time nova-search program. As a result, MAXI has issued 133 Astronomer's Telegrams and 44 Gamma-ray burst Coordinated Networks so far. MAXI has discovered six new black holes (BH) in 4.5 years. Long-term behaviors of the MAXI BHs can be classified into two types by their outbursts; a fast-rise exponential-decay type and a fast-rise flat-top one. The slit camera is suitable for accumulating data over a long time. MAXI issued a 37-month catalog containing 500 sources above a ~0.6 mCrab detection limit at 4-10 keV in the region ${\mid}{b}{\mid}$ > $10^{\circ}$. The SSC instrument utilizing an X-ray CCD has detected diffuse soft X-rays extending over a large solid angle, such as the Cygnus super bubble. MAXI/SSC has also detcted a Ne emission line from the rapid soft X-ray nova MAXI J0158-744. The overall shapes of outbursts in Be X-ray binaries (BeXRB) are precisely observed with MAXI/GSC. BeXRB have two kinds of outbursts, a normal outburst and a giant one. The peak dates of the subsequent giant outbursts of A0535+26 repeated with a different period than the orbital one. The Be stellar disk is considered to either have a precession motion or a distorted shape. The long-term behaviors of low-mass X-ray binaries (LMXB) containing weakly magnetized neutron stars are investigated. Transient LMXBs (Aql X-1 and 4U 1608-52) repeated outbursts every 200-1000 days, which is understood by the limit-cycle of hydrogen ionization states in the outer accretion disk. A third state (very dim state) in Aql X-1 and 4U 1608-52 was interpreted as the propeller effect in the unified picture of LMXB. Cir X-1 is a peculiar source in the sense that its long-term behavior is not like typical LMXBs. The luminosity sometimes decreases suddenly at periastron. It might be explained by the stripping of the outer accretion disk by a clumpy stellar wind. MAXI observed 64 large flares from 22 active stars (RS CVns, dMe stars, Argol types, young stellar objects) over 4 years. The total energies are $10^{34}-10^{36}$ erg $s^{-1}$. Since MAXI can measure the spectrum (temperature and emission measure), we can estimate the size of the plasma and the magnetic fields. The size sometimes exceeds the size of the star. The magnetic field is in the range of 10-100 gauss, which is a typical value for solar flares.