• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1997년도 가을 학술발표회 논문집
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• pp.229-234
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• 1997

The objective of this study is to develop the non crack ready mixed concrete and the high quality concrete under various addition ratios of expansive additives. According to the experiment results, when expansive additive are mixed in concrete mixture by about 6% per cement contents, in W/B of 45~55%, it is found that the strength increase and the shrinkage compensation can be achieved by about 2~3 times. And it is considered to produce high quality concrete and non crack ready mixed concrete.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2013년도 춘계 학술논문 발표대회
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• pp.289-291
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• 2013

This study evaluated basic material properties of finishing mortar in ondol floor using NSB(Non-sinetering binder), and the binder for the purpose of the developing of high performance mortar and reducing crack problem without shrinkage-reduction agent.

• Composites Research
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• 제23권6호
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• pp.39-46
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• 2010

치아의 와동에 수복된 치과용 복합레진을 광(LED) 조사를 통해 정화 수축시키면서 음향방출(acoustic emission, AE) 신호를 검출하였다. 비모수 통계법인 Mann-Whitney법과 Kruskal-Wallis법을 이용하여 시편의 재질과 계면의 접착조건에 따른 AE hit event 수와 최대진폭을 비교 평가하였다. PMMA와 치아시편으로부터 검출된 선호의 최대진폭은 정착조건에 따른 차이가 없었지만 스테인리스 시편으로부터 검출된 신호는 접착조건에 따라 최대 진폭의 차이가 있었다(p<0.05). AE hit event 수는 양호한 접착조건에서 시편의 재질에 따라 차이가 있었고(p<0.05), 세가지 재질의 시편 모두 접착조건이 양호한 실험에서 AE 신호가 적게 검출되었다. SEM을 이용하여 계면에 생성된 캡을 측정한 결과 AE가 많이 검출되고 검출된 신호의 최대 진폭이 큰 시편에서 갱의 폭이 넓고 형성 비율이 높았다.

• 한국주조공학회지
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• 제42권1호
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• pp.3-11
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• 2022

본 연구에서는 전산모사를 활용하여 오스테나이트계 내열강인 HR3C 합금의 수축 결함 파라미터를 확보하고, 건전부 85% 이상의 잉곳 몰드 설계 및 제작을 진행하였다. 잉곳 몰드 설계 단계에서 전산모사를 활용하여 최적의 잉곳 몰드를 설계 및 제작하였으며, 제작한 잉곳 몰드를 통해 시험조업을 수행하였다. 시험조업 후, 절단 및 비파괴 검사를 통해 결함 양상을 분석하여 수축 결함 파라미터와 잉곳 몰드 설계를 검증하였다. 검증 결과를 기반으로 HR3C 합금의 수축 결함 파라미터 (Niyama 인자, 급탕효율인자, 열간 균열 인자 등)를 확보하였으며, 확보한 파라미터를 통해 건전부 85% 이상의 잉곳 몰드 설계 방안을 확보하였다.

• 한국의류학회지
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• 제11권1호
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• pp.79-85
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• 1987

The purpose of this study was to help the consumer about the care of nonwoven fabrics by investigation of the properties such as launderability. shrinkage, color fastness and strenth. Materials used were two types, soft and stiff, of commercial nonwoven fabrics. Deter-gents used were neutral detergents, synthetic detergents and dry cleaning solutions(perch-toro-ethylene) The results of this study were summerized as follows; 1. Laundering of nonwoven fabrics in low temperature is more ideal as morphological changes by laundering in high temperature were more prominent than that in low temperature. 2. Ironing of nonwoven fabrics wants more attention on environmental temperature as the rate of shrinkage in high temperature was higher than that in low temperature. Neutral detergents are more desirable as the rate of shrinkage of nonwoven fabrics by laundering with synthetic detergents was more prominent than that with neutral deter-gents. The rate of shringkage of nonwoven fabrics was not affected by dry cleanining. 3. Special care is wanted in order to prevent color transfer from non woven fabrics to polyester or wool during dry cleaning or laundering as the color fastness test show that color changes of nonwoven fabrics were not affected, but that color stain was increased on polyester or wool. 4. The strength was affected by composition of fibers and types of nonwoven fabrics, soft or stiff.

• 한국연소학회:학술대회논문집
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• 한국연소학회 2014년도 제49회 KOSCO SYMPOSIUM 초록집
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• pp.81-84
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• 2014

A Experimental study on flame extinction behavior was investigated using He curtain flow with counter triple co-flow burner. Buoyancy force was suppressed up to a microgravity level of $10^{-2}-10^{-3}g$ by using He curtain flow. The stability maps were provided with a functional dependency of diluent mole fraction and global strain rate to clarify the differences in flame extinction behavior. The flame extinction curves had C-shapes at various global strain rates. The oscillation and extinction modes were different each other in terms of the global strain rate, and the flames extinction modes could be classified into five modes such as (I) and (II): an extinction through the shrinkage of the outmost edge flame forward the flame center after self-excitation and without self-excitation, respectively, (III): an extinction through rapid advancement of a flame hole while the outmost edge flame is stationary, (IV): self-excitation occurs in the outermost edge flame and the center edge flame and then a donut shaped flame is formed and/or the flame is entirely extinguished, (V): shrinkage of the outermost edge flame without self-excitation followed by shrinkage or survival of the center flame. These oscillation and extinction modes could be identified well to the behavior of edge flame. The result also showed that the edge flame was influenced significantly by the conductive heat losses to the flame center or ambient He curtain flow.

• 국제초고층학회논문집
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• 제6권1호
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• pp.11-19
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• 2017

High-rise buildings move during construction due to time-dependent material properties of concrete (creep and shrinkage), construction sequences, and structural shapes. The building movements, including vertical and horizontal displacements, result from the sum of axial and lateral deformation of vertical members at each level. In addition to the vertical shortenings, the lateral movement induced by differential shortening can have adverse effects on the construction tolerance and serviceability of non-structural elements such as elevators and curtain walls. In this study a construction stage analysis method is developed to predict lateral movement induced by shortening, including the effect of creep and shrinkage. The algorithm of construction stage analysis is combined with the FE analysis program. It is then applied to predict lateral movement of a 58-story reinforced concrete building that was constructed in Kuala Lumpur, Malaysia. Gravity induced lateral movement of this building is predicted by the construction stage analysis. A field three-dimensional laser scanning survey is carried out to verify the prediction results, and satisfactory agreement is obtained.

• 교육시설 논문지
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• 제20권4호
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• pp.35-43
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• 2013

Some results of experimental investigation conducted to assess the effect of cement composite strength and ductility on the shear behavior and crack-damage mitigation of stud connections between existing reinforced concrete frame in school buildings and seismic strengthening elements from cyclically direct shear tests are described. The cement composite strengths include 50 for medium strength and 70 MPa for high strength. Two types of cement composites, strain-hardening cement composite (SHCC) and non-shrinkage mortar, are used for stud shear connection specimens. The special SHCCs are reinforced with hybrid 0.2% polyethylene (PE) and 1.3% polyvinyl alcohol (PVA) fibers at the volume fraction and exhibits tensile strain capacity ranging from 0.2 to 0.5%. Test result indicates that SHCC improves the seismic performance and crack-damage mitigation of stud shear connections compared with stud connections with non-shrinkage mortar. However, the performance enhancement in SHCC stud connections with transverse and longitudinal reinforcements is less notable for those without additional reinforcement.

• 한국연소학회:학술대회논문집
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• 한국연소학회 2014년도 제49회 KOSCO SYMPOSIUM 초록집
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• pp.379-381
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• 2014

Influence of fuel concentration gradient was investigated near flame extinction limit in buoyancy-suppressed non-premixed counterflow flame with triple co-flow burner. The use of He curtain flow produced a microgravity level of $10^{-2}-10^{-3}g$ in He-diluted non-premixed counter triple co-flow flame experiments. Flame stability map was presented based on flame extinction and oscillation near extinction limit. The stability map via critical diluent mole fraction with global strain rate was represented by varying outer and inner He-diluted mole fractions. The flame extinction modes could be classified into five: an extinction through the shrinkage of the outmost edge flame forward the flame center with and without self-excitation, respectively ((I) and (II)), an extinction via the rapid expansion of a flame hole while the outmost edge flame is stationary (III), both the outermost and the center edge flames oscillate, and then a donut shaped flame is formed or the flame is entirely extinguished (IV), a shrinkage of the outermost edge flame without self-excitation followed by shrinking or sustain the inner flame (V).

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2008년도 추계 학술발표회 제20권2호
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• pp.645-648
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• 2008

교량 신축이음장치의 파손 유형을 보면, 그 원인이 주로 후타재와 관련된 부재에서 많이 발생하는것을 알 수 있다. 중차량 통과에 따른 충격과 진동하중으로 인해서 후타재의 파손이 심하게 일어나고, 신축이음장치를 후타재에 고정하기 위해서 사용하는 앵커에서 풀림 현상이 많이 발생하고 있다. 후타재의 파손은 모든 신축이음장치에서 발생하는 현상으로 기존의 후타재로는 신축이음장치의 종류와 관계없이 차량의 충격하중을 충분히 흡수할 수 없으므로, 차량이 교량의 신축이음장치를 통과 할 때에 가해지는 충격하중으로부터 하자 발생원인을 제거하기 위해서는 충격하중을 흡수 할 수 있는 새로운 후타재의 개발이 절실하게 필요한 상황이다. 따라서 본 연구에서는 에폭시변성 폴리우레탄 바인더와 필러(filler), 골재를 사용하여 우수한 성능을 갖는 고내충격성 모르타르를 개발하는데 목적을 두었다.