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        검색결과 343

        261.
        2015.02 서비스 종료(열람 제한)
        Images created by stack imaging spectral amplitudes based on the impact-echo (SIBIE) method are largely one-dimensional because a single frequency domain spectrum for waves reflected below a single point of impact is used to create them. The method has limitations for representing defects in a cross section of a concrete structural element using two-dimensional coordinates. This study focused on defect detection and visualization in a concrete structural element using multiple impacts and accumulated SIBIE. An impactor was used to induce energy at multiple points positioned at prescribed intervals along the structural element. A modified SIBIE method was applied to the collected data for each point and the modified SIBIE images were accumulated to generate one image (an accumulated SIBIE image). As a result, the defect positions could be represented in the cross section of the structural element using a two-dimensional coordinate system. And the method appears to improve upon existing methods to detect voids or other defects in concrete.
        262.
        2015.02 서비스 종료(열람 제한)
        Historical villages are a highly valuable historical and cultural resource to directly/indirectly recognize and experience unique traditional culture in our daily lives. There are eight historical villages worldwide designated by UNESCO's ICOMOS. Preserving and passing these historical villages down to future generations is one of the key imperatives. Such natural disasters as earthquake, heavy snow and damage from storm and flood are potential risk factors of historical villages. Manmade disasters like theft also pose a risk to historical villages. But, it is fire that poses highest risk to historical villages particularly when folk structures in the villages are built by accessible wood, silver grass and straw. Hahoe Village and Yangdong Village in Korea have straw-roofed houses and Shirakawa-go in Japan has silver grass-roofed houses. Combustion characteristics of these roof materials need to be identified in order to enhance fire safety in historical villages. This study used cone calorimeter (ISO 5660-1) to measure combustion characteristics of straw in Korea and silver grass in Japan. It also analyzed Time to Ignition (TTI), Effective Heat of Combustion(EHC), Heat Release Rate(HRR), Total Heat Release(THR), Mass Loss Rate(MLR) and temperature and time of natural ignition. Database on combustion characteristics of straw and silver grass will be used to predict fire property of buildings and structures in historical villages.
        263.
        2014.12 KCI 등재 서비스 종료(열람 제한)
        코르티코트로핀분비인자(Corticotropin-releasing factor)는 스트레스 반응에 관여하는 호르몬으로, 최근 스트레스가 탈모와 같은 피부질환에 영향을 미친다는 보고들이 많아지고 있다. 보고에 따르면, 사람 모낭 배양에서 코르티코트로핀분비인자는 길이생장을 억제하며, 모낭의 조기퇴행을 유도하고 모기질각질형성세포(hair matrix keratinocyte)의 세포사멸을 촉진시킨다. 본 연구에서는 코르티코트로핀분비인자가 모발성장과 모주기조절에 핵심적으로 역할하는 모유두세포에 미치는 영향에 대해 알아보고자 했다. 시상하부-뇌하수체-부신축의 주요 스트레스호르몬들인 코르티코트로핀분비인자, 부신피질자극호르몬, 그리고 코르티솔을 사람 모유두세포에 처리하였다. 흥미롭게도, 코르티코트로핀분비인자가 모발성장과 관련된 사이토카인(KGF, Wnt5a, TGFβ-2, Nexin)의 발현을 변화시키는 것을 관찰하였으며, 세포 내 cAMP의 수준을 증가시켰고, 수용체의 발현을 억제시켰다. 이러한 변화는 수용체의 길항제인 antalarmin과 astressin2B, 또는 PKA 억제제의 전처리로 인해 막을 수 있었다. 코르티코트로핀분비인자는 cAMP/PKA경로를 통해 POMC의 발현을 유도하는데, 사람 모유두세포에서도 이 호르몬의 처리가 POMC mRNA의 발현을 증가시키는 것을 확인할 수 있었으나 부신피질자극호르몬의 변화는 western blot으로는 확인할 수 없었다. 이러한 결과들을 바탕으로, 코르티코트로핀분비인자가 그 수용체를 통해 사람 모유두세포 내 모발성장 관련 사이토카인의 발현을 조절함을 확인하였으며, 이는 코르티코트로핀분비인자의 수용체 길항제가 스트레스성 탈모환자를 위한 치료제 혹은 화장품 소재로써 활용될 수 있음을 보여준다.
        264.
        2014.09 KCI 등재 서비스 종료(열람 제한)
        In order to monitor the developmental features of embryos, larvae, and juveniles of Oryzias latipes (Temminck and Schlegel), Oryzias latipes was caught in river of Shinduck-dong, Yeosu-si, Jeollanam-do, on May 2011, and experiments were carried out in Ichthyology laboratory at Chonnam National University. The blastodisc step was the first level for natural spawning. The optic vesicle, Kupffer's vesicle, myotome began to appear 75 hours 57 minutes later. After blastodisc development, the pectoral fins were made at 143 hours 37 minutes and the tail was separated started at the same time. Hatching was observed at 167 hours 27 minutes after blastodisc. The total length of the hatched larvae was 4.95~5.10 mm (mean, 5.01 mm), the mouth and anus were opened. Larvae used yolk completely after 3 days after hatching. The total length larvae was 5.45~5.56 mm (mean, 5.52 mm) after 8 days after hatching, and appeared the stems for tail. The stems pectoral, anal fin were showed after 14 days and the stems dorsal, ventral fin were appeared after 19 days. For 35 days after hatching, the total length of larvae 13.95~15.30 mm (mean, 14.64 mm), and at this time, fins and body were transferred like the adult Oryzias latipes.
        265.
        2014.09 KCI 등재 서비스 종료(열람 제한)
        We investigated the androgenic effects of 17α-methyltestosterone (MT) on gonadal sex reversal in juvenile red spotted grouper Epinephelus akaara. The fish were immersed in 17α-MT at 1 and 5 mg/L. Treatment method of 17α-MT was once weekly for 4 and 8 weeks. Fish were sampled at 12 months after end of the treatment period in order to histological analysis. At the initiation of an experiment (70 day after hatching), juvenile red spotted grouper have the paired primordial gonads with somatic cells bellow kidney in the posterior portion of the body cavity. Formation of ovarian cavity indicates that the ovarian differentiation beginning at 70 DAH in red spotted grouper. At 12 months after end of the treatment period, control group, 17α-MT 1 mg/L treatment group for 4 and 8 weeks, and 17α-MT 5 mg/L treatment group for 4 weeks were all female. However, sex-changed males without ovarian cavity were observed in the 17α-MT 5 mg/L treatment group for 8 weeks. In grouper, we firstly reported that the red spotted grouper be able to induce the primary males by hormone treatment prior to gonadal sex differentiation.
        266.
        2014.06 KCI 등재 서비스 종료(열람 제한)
        Rapeseed (Brassica napus L.) oil with high oleic acid content is of great interest for both food and non-food uses. The ‘Tamla’ variety, characterized by oleic acid content of approximately 69%, was treated with 1% ethyl methane sulfonate (EMS) to induce mutations in the fatty acid biosynthesis pathway. M1 plants were selfed and subsequent generations (M2, M3, and M4 mutants) were analyzed to identify mutants having increased levels of oleic acid. M2 mutants showed oleic acid content ranging from 13.5% to 76.9% with some mutants (TR-458 and TR-544) having up to 74.7% and 76.9% oleic acid, which was an increase of nearly 5% and 7%, respectively, compared to untreated cv ‘Tamla’. We selected two M3 mutants with >75% oleic acid content. One mutant (TR-458-2) had increased oleic acid (75.9%) and decreased linoleic acid (12.5%) and linolenic acid (4.4%) contents. The other (TR-544-1) showed increased oleic acid content (75.7%) and decreased linoleic acid (13.5%) and linolenic acid (3.3%) contents. The accumulation or reduction of oleic acid content in the selected M4 mutants was also accompanied by a simultaneous decrease or increase in linoleic and linolenic acid contents. The high-oleic lines could be utilized further in breeding programs for improvement of rapeseed oil quality.
        267.
        2014.06 KCI 등재 서비스 종료(열람 제한)
        Fish larvae are immediately exposed to microbes from hatching to maturation of their lymphoid organs, therefore effective innate mechanisms is very important for survival. However, the knowledge of the development of immune system in fish is limited and in demand now. In vertebrates, recombination-activating gene 1 (RAG-1) and immunoglobulin M (IgM) have been considered as very useful markers of the physiological maturity of the immune system. In this study, the expression of the both genes was assessed throughout the early developmental stages of olive flounder larvae (5-55 dph) and used as markers to follow the development of immune system. RAG-1 and IgM mRNA expression was detectable at 5 dph and remained so until 55 dph. These patterns of expression may suggest that the olive flounder start to develop its function around 5 dph. Tissue distribution was found that both genes mRNAs are only expressed in the immune-related organ such as spleen, kidney and gill. The early detection of IgM mRNA led to the investigation of its presence in oocytes. Both RAG-1 and IgM mRNA transcripts were detected in unfertilized oocytes, suggesting that they are maternally transferred. The biological significance of such a phenomenon remains to be investigated.
        268.
        2014.03 KCI 등재 SCOPUS 서비스 종료(열람 제한)
        Since Rigollet first discovered a comet in 1939, many follow-up observations have been made, particularly in Europe. It is now known that the Rigollet comet is identical with the one observed by Herschel in 1788, and thus it is now called 35P/1939 O1 or the Herschel-Rigollet comet. Yumi, a Japanese astronomer, also observed the Rigollet comet in Korea using a 6-inch refractor telescope, and published his data in two Japanese journals (Bulletin of the Observatory of the Government-General of Korea and Publication of the Lecture on Meteorology). In his paper, Yumi also referred to observations by Hirose and Kanda in Japan. However, their works have not been given attention by international society. In this study, we analyze the observation data of Yumi and present preliminary orbital elements using it with a modified Gauss method. We expect that this study will be used to refine the orbital elements of the Rigollet comet by orbital-calculation experts. For that reason, we have also transcribed all the observational data presented by Yumi.
        269.
        2014.03 KCI 등재 SCOPUS 서비스 종료(열람 제한)
        This paper describes an experimental approach to evaluate the effective doses of space radiations at high-altitude by combining the measured data from the Liulin-6K spectrometer loaded onto the air-borne RC-800 cockpit and the calculated data from CARI-6M code developed by FAA. In this paper, 15 exposed dose experiments for the flight missions at a highaltitude above 10 km and 3 experiments at a normal altitude below 4 km were executed over the Korean Peninsula in 2012. The results from the high-altitude flight measurements show a dramatic change in the exposed doses as the altitude increases The effective dose levels (an average of 15.27 μSv) of aircrew at the high-altitude are an order of magnitude larger than those (an average of 0.30 μSv) of the normal altitude flight. The comparison was made between the measure dose levels and the calculated dose levels and those were similar each other. It indicates that the annual dose levels of the aircrew boarding RC- 800 could be above 1 mSv. These results suggest that a proper procedure to manage the exposed dose of aircrew is required for ROK Air Force.
        270.
        2013.12 KCI 등재 SCOPUS 서비스 종료(열람 제한)
        Ganui-Dae, built in the reign of King Sejong, Joseon Dynasty, is a comprehensive observatory. It has various instruments for observation and time signal such as Ganui, Gyupyo(Gnomon), water-hammering type Honui and Honsang, and so on. Studying on Ganui-Dae has been focused on its location, history, criterion, etc, so far. However, studying on its external form and construction method has been conducted insufficiently. This study suggests the model for restoration of Ganui-Dae. The model is based on the analysis about external form of Ganui-Dae in various antique maps, and its construction method in those days.
        271.
        2013.10 서비스 종료(열람 제한)
        This study utilizes an equation proposed for the calculation of the lateral-torsional buckling moment of a reinforced concrete beam to evaluate the lateral rollover stability of a precast concrete girder particularly during construction. The result of this study showed the lateral-torsional capacity of a girder significantly decreased with an increase in the initial sweep of the girder. The capacity of a girder with the initial sweep in the order of around two times the PCI tolerance becomes smaller than its ultimate flexural capacity.
        272.
        2013.10 서비스 종료(열람 제한)
        Image created by stack imaging spectral amplitudes based on the impact-echo (SIBIE) method is largely one-dimensional because a single frequency domain spectrum for wave reflected below a single point of impact is used to create the image. The method has limitations for representing defects in a cross section of a concrete structural element using two-dimensional coordinates. This study focused on defect detection and visualization in a concrete structural element using multiple impacts and accumulated SIBIE. An impactor was used to induce energy at multiple points at positioned at prescribed intervals along the structural element. A modified SIBIE method was applied to the collected data of each point and the modified SIBIE images were accumulated to generate one image (an accumulated SIBIE image).
        273.
        2013.09 KCI 등재 SCOPUS 서비스 종료(열람 제한)
        Honsangui (celestial globe) which is a water-hammering method astronomical clock is recorded in 「Juhaesuyong」 which is Volume VI of supplement from 『Damheonseo』, written by Hong Dae-Yong (1731~1783). We made out the conceptual design of Hong Dae-Yong’s Honsangui through the study on its structure and working mechanism. Honsangui consist of three rings and two layers, the structure of rings which correspond to outer layer is similar to his own Tongcheonui (armillary sphere) which is a kind of armillary sphere. Honsang sphere which correspond to inner layer depicts constellations and milky way and two beads hang on it as Sun and Moon respectively for realize the celestial motion. Tongcheonui is operated by the pendulum power but Honsangui is operated by water-hammering method mechanism. This Honsangui’s working mechanism is the traditional way of Joseon and it was simplified the working mechanism of Shui yün i hsiang t'ai which is a representative astronomical clock of China. This record of Honsangui is the only historical record about the water-hammering method working mechanism of Joseon Era and it provide the study of water-hammering method mechanism with a vital clue.
        274.
        2013.06 KCI 등재 SCOPUS 서비스 종료(열람 제한)
        In this paper we examine a total of 16 dipolarization events that were observed by THEMIS spacecraft in space close togeosynchronous orbit, r < ~ 7 RE. For the identified events, we examine the characteristics of the plasma flows and associatedbubbles as defined based on pV5/3, where p is the plasma pressure and V the volume of unit magnetic flux. First, we find thatthe flow speed in the near-geosynchronous region is very low, mostly within a few tens of km/s, except for a very few events forwhich the flow can rise up to ~200 km/s but only very near the dipolarization onset time. Second, the bubble parameter, pV5/3,decreases by a much smaller factor after the dipolarization onset than for the events in the farther out tail region. We suggestthat the magnetic dipolarization in the near-geosynchronous region generates or is associated with only very weak plasmabubbles. Such bubbles in the near-geosynchronous region would penetrate earthward only by a small distance before theystop at an equilibrium position or drift around the Earth.
        275.
        2013.03 KCI 등재 SCOPUS 서비스 종료(열람 제한)
        The use of generating functions for solving optimal rendezvous problems has an advantage in the sense that it does not require one to guess and iterate the initial costate. This paper presents how to apply generating functions to analyze spacecraft optimal reconfiguration between projected circular orbits. The series-based solution obtained by using generating functions demonstrates excellent convergence and approximation to the nonlinear reference solution obtained from a numerical shooting method. These favorable properties are expected to hold for analyzing optimal formation reconfiguration under perturbations and non-circular reference orbits.
        276.
        2012.09 KCI 등재 SCOPUS 서비스 종료(열람 제한)
        We conducted thermal analyses and cooling tests of the space observation camera (SOC) of the multi-purpose infrared imaging system (MIRIS) to verify passive cooling. The thermal analyses were conducted with NX 7.0 TMG for two cases of attitude of the MIRIS: for the worst hot case and normal case. Through the thermal analyses of the flight model, it was found that even in the worst case the telescope could be cooled to less than 206°K. This is similar to the results of the passive cooling test (~200.2°K). For the normal attitude case of the analysis, on the other hand, the SOC telescope was cooled to about 160°K in 10 days. Based on the results of these analyses and the test, it was determined that the telescope of the MIRIS SOC could be successfully cooled to below 200°K with passive cooling. The SOC is, therefore, expected to have optimal performance under cooled conditions in orbit.
        277.
        2012.06 KCI 등재 SCOPUS 서비스 종료(열람 제한)
        We analyzed the manufacturing procedure, specifications, repair history, and details of celestial movements of the water-hammering type Honsang (celestial globe). Results from our study on the remaining Honsangs in China and Japan and on the reconstruction models in Korea were applied to our conceptual design of the water-hammering type Honsang. A Honui (armillary sphere) and Honsang using the water-hammering method were manufactured in Joseon in 1435 (the 17th year of King Sejong). Jang Yeong-Sil developed the Honsang system based on the water-operation method of Shui yün i hsiang t’ai in China. Water-operation means driving water wheels using a water flow. The most important factor in this type of operation is the precision of the water clock and the control of the water wheel movement. The water-hammering type Honsang in Joseon probably adopted the Cheonhyeong (天衡; oriental escapement device) system of Shui yün i hsiang t’ai in China and the overflow mechanism of Jagyeongnu (striking clepsydra) in Joseon, etc. In addition to the Cheonryun system, more gear instruments were needed to stage the rotation of the Honsang globe and the sun’s movement. In this study, the water-hammering mechanism is analyzed in the structure of a water clock, a water wheel, the Cheonhyeong system, and the Giryun system, as an organically working operation mechanism. We expect that this study will serve as an essential basis for studies on Heumgyeonggaknu, the water-operating astronomical clock, and other astronomical clocks in the middle and latter parts of the Joseon dynasty.
        278.
        2012.02 서비스 종료(열람 제한)
        Image created by stack imaging spectral amplitudes based on the impact-echo (SIBIE) method is largely one-dimensional because a single frequency domain spectrum for wave reflected below a single point of impact is used to create the image. The method has limitations for representing defects in a cross section of a concrete structural element using two-dimensional coordinates. This study focused on defect detection and visualization in a concrete structural element using multiple impacts and accumulated SIBIE. An impactor was used to induce energy at multiple points at positioned at prescribed intervals along the structural element. A modified SIBIE method was applied to the collected data of each point and the modified SIBIE images were accumulated to generate one image (an accumulated SIBIE image). As a result, the defect positions could be represented in the cross section of the structural element using a two-dimensional coordinate system.
        279.
        2011.12 KCI 등재 서비스 종료(열람 제한)
        To find an alternative for synthetic pesticides, methanol extracts from 69 plant samples were tested for their insecticidal activity against two spotted mite (Tetranchus urticae Koch). Seven plant extracts including Angelica japonica showed over 80% insecticidal activity at 5000 mg/L. Extract of Prunus armeniaca seed showed high insecticidal activity at 3000 mg/L. As a naturally occurring pesticide, P. armeniaca could be useful as a new botanic insecticide.
        280.
        2011.12 KCI 등재 서비스 종료(열람 제한)
        The test was carried out at a test field at the Wanju Eco-Farming Complex from 2009 to 2010 to figure out the proper application of fertilizers when growing rice at the EcoFarming Complex. The result showed that when compared to the basal application of compost as fertilizer, applying supplementary compost after natural re-seeding of chinese milk vetch (CM씨 helped balance soìl nutrìtìon and maìntained rice yields.