• 한국철도학회:학술대회논문집
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• 한국철도학회 2002년도 추계학술대회 논문집(I)
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• pp.596-600
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• 2002

To analyze the settlement characteristics of short-fiber reinforced soil(SFRS), which will be used as a new backfill material of reinforced retaining wall, under simulated railroad loading, a series of tests with loading condition of 5 Hz frequency and 500,000 cycles were performed. The materials used for tests are soils with SM or ML type, and polypropylene short-fibers with mono-filament(PPM) or fibrillated type(PPF). From the tests, average plastic settlement is low at PPF38(0.3%)(abbreviation of PPF with 38mm length and mixing ratio 0.3%), PPF38(0.5%), PPM60(0.2%) for SFRS using SM soil and at PPF38(0.3%), PPF60(0.2%) for SFRS using ML soil. Elastic settlement is low at PPM60(0.2%) for SFRS using SM soil and at PPM60(0.5%) for SFRS using ML soil.

• 천문학회보
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• 제46권1호
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• pp.55.1-55.1
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• 2021

Ram-pressure stripping (RPS) is known as a typical mechanism of quenching star formation (SF) of galaxies orbiting in clusters, but it can also boost the SF activity within a short period of time. Jellyfish galaxies, with eye-catching blue tails and knots, are such starburst galaxies undergoing strong RPS in galaxy clusters. Thus, they are very useful targets to understand their SF activity in relation to RPS. We study the SF activity of three jellyfish galaxies in massive clusters at z=0.3-0.4 (MACSJ1752-JFG2, MACSJ0916-JFG1, and A2744-F0083) with Gemini GMOS/IFU and compare our results to those of jellyfish galaxies in low-mass clusters. We obtain total star formation rates (SFRs) of up to 60 Mo/yr and SFRs in the tails of up to 15 Mo/yr, which are much higher than those of jellyfish galaxies in low-mass clusters with the median SFRs of 1.1 Mo/yr in total and 0.03 Mo/yr in tails. In addition, these SFRs are also significantly higher than the SF main sequence of galaxies at the redshifts of the three jellyfish galaxies. This implies that their SF activity is much more enhanced compared to jellyfish galaxies in low-mass clusters due to extreme RPS in massive clusters.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1994년도 가을 학술발표회 논문집
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• pp.429-434
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• 1994

In this study, an experiment in the field was performed to analyze the variations of rebound ratios of SFRS with silica fume after fabricating the panels and placing the plain concrete of simulting a base rock with thickness 7cm. And the experimental parameters which are the reinforcing methods(steel fiber, wire mesh), steel fiber contents(0.0%, 0.5%, 0.75%, 1.0%), silica fume contents(0.0%, 10.0%), and the three parts(lower, middle, upper part) were chosen. According to the results of the lower part in this test, the larger the fiber contents are in case of steel fiber reinforced shotcrete, the less the rebound ratios are within the range of 20~35%, compared to the wire-mesh reinforced shotcrete with silica fume content of 10%, and these results are true of the middle and upper part, respectively. In addition, the four-stage phenomena of the rebound of SFRS were estimated on the base of a series of the test results.

• 한국농공학회:학술대회논문집
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• 한국농공학회 2002년도 학술발표회 발표논문집
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• pp.321-324
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• 2002

To analyze the settlement characteristics of short-fiber reinforced soil(SFRS) under dynamic loading, a series of tests with loading condition of 5 Hz frequency and 500,000 cycles were performed. The materials used for tests are a soil of SM type and short-fibers with polypropylene and monofilament or fibrillated type. From the tests, average plastic settlement of SFRS at PPF38(0.3%), PPF38(0.5%), PPM60(0.2%) is low. Elastic settlement of SFRS is low at PPM60(0.2%) and is high at PPF60(0.5% ).

• 한국안전학회지
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• 제13권2호
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• pp.122-129
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• 1998

A field experiment was performed to analyze the properties of SFRS(steel fiber reinforced shotcrete) against WMRS(wire mesh reinforced shotcrete) with some experimental parameters. The parameters were reinforcing methods(steel fiber and wire mesh), steel fiber contents(0.5%, 0.75%, and 1.0%), silica fume contents(0.0% and 10.0%), spraying thicknesses of layer(10㎝, 8㎝, and 6㎝), and spraying parts(side wall, shoulder, and crown). According to the analyzed results, the mechanical properties of SFRS such as compressive strength, flexural strength, and load-carrying capacity after cracks were improved. And the economic evaluation was also performed on the basis of the required thickness of the layer and other researcher's results for rebound ratios. From the results of this tests, it is found that the traditional WMRS may be substituted by the SFRS in the viewpoint of the economic evaluation as well as the mechanical properties. In additions, the silica fume, even if it is very expensive, can significantly improve the mechanical properties of the shotcrete regardless of mixing with or without the steel fiber.

• Nuclear Engineering and Technology
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• 제47권3호
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• pp.260-266
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• 2015

Twenty sodium-cooled fast reactors (SFRs) have provided valuable experience in design, licensing, and operation. This paper summarizes the important safety criteria and safety guidelines of intermediate sodium systems, steam generators, decay heat removal systems and associated construction materials and in-service inspection. The safety criteria and guidelines provide a sufficient framework for design and licensing, in particular by new entrants in SFRs.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2002년도 가을 학술발표회 논문집
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• pp.695-702
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• 2002

Shotcrete (or Sprayed concrete) has been used as an important support material in New Austrian Tunnelling Method (NATM). Since the mid of 1990, permanent shotcrete tunnel linings such as Single-shell, NMT (Norwegian Method of Tunnelling) has been constructed in many countries for reducing the construction time and lowing construction costs instead of conventional in-situ concrete linings. Among essential technologies for successful application of permanent shotcrcte linings, high performance shotcrete providing high strength, high durability, better pumpability has to be developed in advance as an integral component. This paper presents the Ideas and first experimental attempts to increase early strength and bond strength of wet-mixed Steel Fiber Reinforced Shotcrete(SFRS) in sump water condition. In order to increase early strength, a new approach using high-early strength cement with liquid alkali-free accelerator has been investigated From the results, wet-mix SFRS with high-early strength cement and alkali-free accelerator exhibited excellent early strength improvement compared to the ordinary portland content and good bond strength even under sump water condition.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2002년도 봄 학술발표회 논문집
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• pp.1023-1030
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• 2002

From the early 1980s, the New Austrian Tunnelling Method (NATM) has been developed as a one of the standard tunneling method in Korea. Approximately 10 years ago, wet-mix shotcrete with sodium silicate accelerator (waterglass) was introduced and widely used to tunnel lining and underground support. However, this accelerator had some disadvantages due to the decrease of long-term strength compared to plain concrete (without accelerator) and low quality of the hardened shotcrete. In order to compensate for these disadvantages, recently developed alkali-free accelerator has been successfully demonstrated in numerous projects and applications as a new material to make tunnels more durable and safer. An experimental investigation was carried out in order to verify the strength behavior of wet-mix Steel Fiber Reinforced Shotcrete (SFRS) with alkali-free accelerator. Compressive strength, flexural strength and equivalent flexural strength were measured by testing specimens extracted from the shotcrete panels. From the results, wet-mix SFRS with alkali-free accelerator exhibited excellent strength improvement compared to the conventional shotcrete accelerator.

• 천문학회보
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• 제41권2호
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• pp.55.2-55.2
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• 2016

In this talk, I will present a theoretical and numerical framework for self-regulation of the star formation rates (SFRs) in disk galaxies. The theory assumes (1) force balance between pressure support and the weight of the interstellar medum (ISM), (2) thermal balance between radiative cooling in the ISM and heating via FUV radiation from massive young stars, and (3) turbulent energy balance between dissipation in the ISM and driving by momentum injection of SNe. Numerical simulations show vigorous dynamics in the ISM at all times, but with proper temporal and spatial averages, all the expected balances hold. This leads to a scaling relation between mean SFRs and galactic gas and stellar properties, arising from the fundamental relationship between SFR surface density and the total midplane pressure.

• 천문학논총
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• 제33권2호
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• pp.21-30
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• 2018

Formation processes of high-mass stars have been long-standing issues in astronomy and astrophysics. This is mainly because of major difficulties in observational studies such as a smaller number of high-mass young stellar objects (YSOs), larger distances, and more complex structures in young high-mass clusters compared with nearby low-mass isolated star-forming regions (SFRs), and extremely large opacity of interstellar dust except for centimeter to submillimeter wavelengths. High resolution and high sensitivity observations with Atacama Large Millimeter/Submillimeter Array (ALMA) at millimeter/submillimeter wavelengths will overcome these observational difficulties even for statistical studies with increasing number of high-mass YSO samples. This review will summarize recent progresses in high-mass star-formation studies with ALMA such as clumps and filaments in giant molecular cloud complexes and infrared dark clouds (IRDCs), protostellar disks and outflows in dense cores, chemistry, masers, and accretion bursts in high-mass SFRs.