• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2004년도 추계 학술발표회 제16권2호
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• pp.707-710
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• 2004

This paper reported the results of mock-up test on mass concrete for transfer girder using setting time difference of super retarding agent(SRA). According to test results, two mock-up structures were made. Plain concrete without placing layer reached maximum temperature after 24hours since placement and caused surface hydration cracks at top section. However, concrete with placing layer reached maximum temperature after 72hours and surface temperature was higher than center temperature, which did not cause surface crack. After form removing, no crack was observed at side surface of plain concrete, while concrete using SRA at mid section had surface scaling and settling crack. According to coring results, concrete with placing layer had a penetration crack from top section to bottom section. Therefore, the setting time difference method to reduce hydration heat will have difficulty in applying the mass concrete for transfer girder.

• Animal Systematics, Evolution and Diversity
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• 제22권1호
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• pp.17-22
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• 2006

Cryptocercus nymphs periodically groom ventral surface of their parents. The grooming might be licking-behavior to obtain secretions from the ventral surface of their parents, and some essential nutrients or hormones that facilitate nymphal development might be included in the secretions. We tried to find morphological structures for secretion outlets on the ventral surface. The deep depressions around setae were present, and their shape was an external morphological structure that liquid secretions from internal glands are likely to be well seized. There were also small holes on the depressions that might be external openings for secretions from the sternal glands. Another possible region on body surface for outlets of secretions might be the apophyses. In Cryptocercus individuals, mucous liquid on body surface was relatively highly present around coxa. The intercoxal apodemes, to which muscles are attached and which open externally between the mid and hindcoxae, might have evolved a secondary function of producing nourishment for the young.

• 대기
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• 제29권1호
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• pp.87-103
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• 2019

이 기술 노트에서는 중간복잡도 지구시스템모델의 하나인 LOVECLIM의 1.3 버전의 특성과 설치 및 운영 방법을 살펴보았으며, 두 종류의 홀로세의 기후 실험을 수행하고 그 결과를 기존 CMIP5/PMIP3실험결과와 비교, 분석하였다. 이 연구에서 수행된 홀로세 중기 평형기후실험과 홀로세 중기부터 현재까지의 점진적 기후변화 실험 결과를 CMIP5/PMIP3 실험 결과와 비교하여 살펴본 결과, 연직 3층의 준지균 근사 방정식을 사용하는 LOVECLIM의 대기모델은 지면대기 온도, 200 hPa 동서방향 바람, 800 hPa 남북방향 바람의 전구 분포의 공간상관도와 편차에서 CMIP5/PMIP3에 참여한 최신의 기후모델들에 비하여 상대적으로 낮은 대기장의 모의정확도를 보였지만, 전구 지면온도의 분포 및 변화, 대륙 연안 지역의 800 hPa 바람장, 200 hPa 동서방향 바람장 등은 최신의 기후모델과 유사한 모의 특성을 보였다. 특히 최근 6천년간의 장기 기후변화 실험은 단일 CPU 환경에서 약 4일 정도의 적분을 통해 수행되었음에도 CMIP5/PMIP3 기후모델들에서 모의된 두 시기의 지면온도의 주요한 차이를 잘 모의하고 있는 것으로 나타났다. 이렇듯 중간복잡도 지구시스템모델은 상대적으로 낮은 정확도로 인하여 범용적인 연구 도구로 활용되기에는 한계가 있지만, 고기후 등 특정 분야의 연구에서는 매우 유용한 연구 도구로 활용될 수 있다. 이러한 활용성은 중간복잡도 지구시스템모델을 이용한 여러 연구 결과들에서도 살펴볼 수 있으며, 이 기술 노트에서 소개된 LOVECLIM의 특성 및 설치 과정이 LOVECLIM을 이용한 다양한 국내 연구에 기여할 수 있길 기대한다.

• 천문학회보
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• 제46권1호
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• pp.57.2-57.2
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• 2021

Variability in Young Stellar Objects (YSOs) can be caused by time-dependent accretion rates, geometric changes in the circumstellar disks, the stochastic hydromagnetic interactions between stellar surfaces and inner disk edges, reconnections within the stellar magnetosphere, and hot/cold spots on stellar surfaces. We uncover ~1400 variables from a sample of ~5300 YSOs in nearby low-mass star-forming regions using mid-IR light curves obtained from the 5.5-years NEOWISE All Sky Survey. The mid-IR variability traces a wide range of dynamical, physical, and geometrical phenomenon. We classify six types of YSO variability based on their light curves: secular variability (Linear, Curved, Periodic) and stochastic variability (Burst, Drop, Irregular). YSOs in earlier evolutionary stages have higher fractions of variables at all types and higher amplitudes for the variability. Along with brightness variability, we also find a diverse range of secular color variations, which can be attributed to a competitive interplay between the variable accretion luminosity of the central source and the variable extinction by material associated with the accretion process. We compare the variability of known FUors/EXors and VeLLOs/LLSs, which represent two extreme ends (burst versus quiescent) of the episodic accretion process; FUors/EXors have a higher fraction of variables (65%) than VeLLOs/LLSs (41%). Short-term (few day) and long-term (decades) variability, as well as possible AGB contamination in the YSO catalogues, are also discussed.molecules become more complex by surface chemistry induced directly by high energy photons or by the thermal energy diffused over heated grain surface. Therefore, the ice composition is an

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2009년도 추계학술대회 논문집
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• pp.72-75
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• 2009

Design and Manufacturing processes of Ti-6Al-4V profiled ring-products were investigated with three-dimensional FEM simulation and experimental analyses. FEM simulation for the ring-rolling process was used to calculate the state variables such as strain, strain rate and temperature. In the simulation results of strain and temperature distributions for a plane ring rolling process, the strain level at the surface area is higher than that at the mid-plane, but the temperature level at the surface area is lower than that at mid-plane due to heat transfer between the workpiece and the work roll. These distributions showed a great influence on the evolution of microstructure in different positions. In order to induce the uniform deformation of the profile ring and reduce the applied load, the final blank was prepared by two-step processes. The mechanical properties of Ti-6Al-4V alloy ring products made in this work were investigated with tensile and impact tests and analyzed with the evolution of microstructures during the ring rolling process.

• 국제초고층학회논문집
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• 제9권2호
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• pp.175-185
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• 2020

Currently, few studies have been conducted to comprehend the seismic reliability of post-tensioned (PT) CLT shear wall structures, due to the complexity of this kind of structural system as well as due to lack of a reliable structural model. In this paper, a set of 4-, 8-, 12-, and 16-storey benchmark PT CLT shear wall structures (PT-CLTstrs) were designed using the direct displacement-based design method, and their calibrated structural models were developed. The seismic reliability of each PT-CLTstr was assessed based on the fragility analysis and based on the response surface method (RSM), respectively. The fragility-based reliability index and the RSM-based reliability index were then compared, for each PT-CLTstr and for each seismic hazard level. Results show that the RSM-based reliabilities are slightly less than the fragility-based reliabilities. Overall, both the RSM and the fragility-based reliability method can be used as efficient approaches for assessing the seismic reliabilities of the PT-CLTstrs. For these studied mid- and high-rise benchmark PT-CLTstrs, following their fragility-based reliabilities, the 8-storey PT-CLTstr is subjected to the least seismic vulnerability; while, following their RSM-based reliabilities, the 4-storey PT-CLTstr is subjected to the least seismic vulnerability

• 해양환경안전학회지
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• 제22권3호
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• pp.286-295
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• 2016

With the results of observations in 2013 and 2014 including ocean buoys, in-situ investigations and wind data, we examined the spatio-temporal variation of cold water masses along the eastern coast of Korea. Usually, a cold water mass first appears along the northern part of the eastern coast from May to July, and then along the southern part of the eastern coast from late June to mid-August. Cold water masses appear 3~5 times a year and remain for 5~20 days in the southwestern part of the East Sea. A distinctive cold water mass appeared usually in mid-July in this area, the surface temperature of which was below $10^{\circ}C$ in some cases. During the appearance of a cold water mass in the southwestern part of the East Sea, the horizontal temperature gradient was large at the surface and a significant low water temperature below $8^{\circ}C$ appeared at the bottom level. This appearance of cold water masses clearly corresponded to southwesterly winds, which generated coastal upwelling.

• Wind and Structures
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• 제13권2호
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• pp.127-144
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• 2010

Pressure measurements on static and autorotating flat plates have been recently reported by Lin et al. (2006), Holmes, et al. (2006), and Richards, et al. (2008), amongst others. In general, the variation of the normal force with respect to the angle of attack appears to stall in the mid attack angle range with a large scale separation in the wake. To date however, no surface pressures have been measured on auto-rotating plates that are typical of a certain class of debris. This paper presents the results of an experiment to measure the aerodynamic forces on a flat plate held stationary at different angles to the flow and allowing the plate to auto-rotate. The forces were determined through the measurement of differential pressures on either side of the plate with internally mounted pressure transducers and data logging systems. Results are presented for surface pressure distributions and overall integrated forces and moments on the plates in coefficient form. Computed static force coefficients show the stall effect at the mid range angle of attack and some variation for different Reynolds numbers. Normal forces determined from autorotational experiments are higher than the static values at most pitch angles over a cycle. The resulting moment coefficient does not compare well with current analytical formulations which suggest the existence of a flow mechanism that cannot be completely described through static tests.

• Ocean and Polar Research
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• 제24권3호
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• pp.267-278
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• 2002

This study investigated the spatial characteristics of warming trends and the dipole-like pattern of temperature field in the Antarctic Peninsula using surface air temperature (SAT) of 10 stations in the vicinity of the Antarctic Peninsula. SAT data for the 1962-2001 period at 6 stations (Rothera, Faraday/Vernadsky, Bellingshausen, Orcadas, Esperanza, Halley) revealed in general the larger warming trends in autumn and winter except for Halley. The largest warming was shown for August in the west side of the Peninsula (more than $0.9^{\circ}C/decade$). On the other hand, the recent 14-year SAT data showed the strong warming trends at 9 stations except for Halley in the earlier period (April-June) than August for the 1962-2001 period. The largest warming appeared in May at Esperanza and Butler Island. SAT of the two sides showed significant positive correlations over most of the period except for the mid- and the late 1970s, in which significant negative correlations were found. In the correlation analysis between SAT and sea surface temperature (SST) anomalies in the NINO 3.4 region, strong negative correlation was found in the west side of the Peninsula. Details of the correlation analysis exhibited that the negative correlation was significantly strong from the early 1980s to the mid-1990s. However, it was difficult to find significant correlations of ENSO with SAT in the east side of the Peninsula. So, in this study it failed to find out clearly the out-of-phase relationship of SAT across the Antarctic Peninsula.

• 대한치과의사협회지
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• 제19권7호통권146호
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• pp.625-634
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• 1981

A Scanning Electron Microscopic Study of the root surface changes was carried out in advanced periodontal disease. The results obtained were summerized as follow; 1. The root surface of cementoenamel junction of healthy root showed smooth surface, while the root surface of diseased state showed covering of deposits which regareded as a course of calcification. 2. At the mid-portion of the root, the regular cemental projection were observed on the healthy root surface and on the root surface of diseased state, cemental projection showed relatively irregular pattern. 3. On the root surface which consist of wall of periodontal pocket, there were various deposits which could be considered as subgingival calculus, bacterial plaque and epithelial attachment remnant. 4. The bottom area of the pathologic pocket, tearing altered collagen fibers were seen on the root surface. 5. At the apical portion of root surface, calcified fibers ran parallel to the root surface in healthy tooth and the fiber bundles of periodontal ligament were seen in the diseased state.