• 조명전기설비학회논문지
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• 제13권4호
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• pp.120-126
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• 1999

수명예측을 하기 위한 기초자료로 ACSR의 기계적 시험의 일종인 인장시험이 필요하다. 이 인장시험의 결과들이 경년 변화에 대해 어떤 상관관계가 있는가를 파악하여 통계적으로 처리함으로써 수명예측을 해 볼 수 있다. 통계적 처리기법으로는 회귀분석 방법이 일반적이다. 본 연구에서는 ACSR의 인장시험을 건전 전선과 수거된 경년 변화를 갖는 전선에 대해 실시하였다. 수명예측의 한계는 캐나다 Ontario Hydro Research의 기준인 정격 인장강도의 20[%] 손실점을 택하였다. 본 연구에 이용된 ACSR의 규격은 $95[\textrm{mm}^2]$, $97[\textrm{mm}^2]$, $120[\textrm{mm}^2]$, $240[\textrm{mm}^2]$ 를 대상으로 하여 선형회귀분석과 비선형 회귀분석을 실시하여 예측수명을 제시하였다. 분석프로그램으로는 SPSS와 Matlab의 Statistics Toolbox를 이용하였다.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 1999년도 토목섬유 학술발표회 논문집
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• pp.105-116
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• 1999

The Inchon International Airport site was formed by reclaimed soil from the sea. The average thickness of soft soil Is about 5 m and most of soft soils are normally consolidated or slightly over consolidated. There are many box culverts which are being constructed under the runways in the airfield. Sometimes, differential settlement can be occurred in the adjacent of box culvert or underground structures at the top layer of runway Soil compaction at very near to the structure is not easy all the time. Thus, one layer of geogrid was placed at the bottom of lean concrete layer for the concrete paved runway and at the middle of cement stabilized sub-base course layer for the asphalt paved runway. The length of geogrid reinforcement is 5m from the end of box culvert for both sides. The extended length of geogrid was 2m from the end of backfill soil in the box culvert. The tensile strength tests of geogrid were conducted for make sure the chemical compatibility with cement treated sub-base material. The location of geogrid placement for the concrete paved runway was evaluated. The construction damage to the geogrid could be occurred. Because the cement treated sub-base layer or lean concrete was spread by the finisher. The magnitude of tensile strength reduction was 1.16%~1.90% due to the construction damage and the ultimate tensile strength is maintained with the specification required. Total area of geogrid placement in this project is about 50,000 $m^2$.

• Journal of Welding and Joining
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• 제26권6호
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• pp.54-58
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• 2008

Laser welding with AZ61 filler wire was carried out to improve formability though reduction of porosity and formation of under fill bead. Optimum welding condition and mechanical properties of butt joint for $400{\times}500{\times}1.3mm$ magnesium sheets were studied. Optimal welding conditions of laser power, welding speed, and defocusing length are 1000W, 3m/min, and 2mm, respectively. Results of tensile test indicated that both tensile strength and elongation of specimens welded with filler wire were improved at room temperature because of reduction of porosity and under-filled bead formation in addition to the precipitation hardening and microstructure refinement by Al-Mn and Mg-Al-Zn precipitates. At elevated temperature of $200{\sim}350^{\circ}C$, fracture location of tensile specimen was shifted from weld metal to base metal, indicating less softening of weld metal than base metal.

• 대한치과보철학회지
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• 제38권4호
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• pp.510-525
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• 2000

The effects of pretreatment of Co-Cr alloy, including two adhesive primers that contain either MDP or MAC-10, and silicoating on the bond The result sobtained as follows; o Strength of 4-META/MMA-TBB resin were investigated using FT-IR, SEM, and EDAX. o In the SEM observation of surface morphologies, the sandblasted specimen exibited a very rough surface, whereas the surfaces of the two groups primed with either MDP or MAC-10 were covered with a layer of primer, and the surface morphology of the silicoated specimen remained almost the same after sandblasting. o Before the thermocycling tests, the group treated with MDP demonstrated the highest mean tensile bond strength and the sandblasted group showed the lowest bond strength. o After 20,000 thermocyling, the mean tensile bond strength of the sandblasted group exhibited a 50% reduction in bond strength, while the others showed a $20\sim30%$ reduction. o Observation of the metal-resin interface revealed that in all groups the resin permeated the rough surface formed by sandblasting thereby producing a mechanical bond between the metal and the resin. It was also found that thermocycling resulted in a gap formation at the metal-resin interface of the specimens, and the sandblasted group exhibited a larger gap width than the other groups. o In fracture mode, all specimens indicated a cohesive fracture within the resin before thermocycling. However, thermocyling produced adhesive failure at the edge of the resin-metal interface in most specimens. The sandblasted group, which exhibited the lowest bond strength after thormocycling, also demonstrated the largest area of adhesive failure.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2005년도 춘계 학술발표회 논문집
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• pp.561-568
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• 2005

The factors affecting the long-term design strength of geogrid can be classified into factors on creep deformation, installation damage, temperature, chemical degradation and biological degradation. Especially, creep deformation and installation damage are considered as main factors to determine the long-term design strength of geogrid. Current practice in the design of reinforced soil is to calculate the long-term design strength of a reinforcement damaged during installation by multiplying the two partial safety factors, $RF_{ID} and RF_{CR}$. This method assumes that there is no synergy effect between installation damage and creep deformation of geogrids. Therefore, this paper describes the results of a series of experimental study, which are carried out to assess the combined effect of installation damage and creep deformation for the long-term design strength of geogrid reinforcement. The results of this study show that the tensile strength reduction factors, RF, considering combined effect between installation damage and creep deformation is less than that calculated by the current design method.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2005년도 추계 학술발표회 제17권2호
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• pp.575-578
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• 2005

Recently, various concrete reinforcing fibers have been used to reduce the plastic shrinkage cracking which occurs before the concrete hardens. In this study, the physical properties of nylon fiber reinforced concrete such as slump, air content, compressive strength and tensile strength were investigated. In addition, the performance of nylon fiber in the plastic shrinkage cracking reduction of mortar has been estimated in comparison with polypropylene fiber and cellulose fiber. Nylon fiber showed considerable advantages in terms of the workability of concrete and the plastic shrinkage cracking reduction of mortar compared with polypropylene fiber and cellulose fiber.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2006년도 추계 학술발표회 논문집
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• pp.661-664
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• 2006

Recently, various concrete reinforcing fibers have been used to reduce the plastic shrinkage cracking which occurs before the concrete hardens. In this study, the physical properties of nylon fiber reinforced concrete such as slump, air content, compressive strength and tensile strength were investigated. In addition, the performance of nylon fiber in the plastic shrinkage cracking reduction of concrete has been estimated in comparison with polypropylene, poly vinyl alcohol fiber and cellulose fiber. Nylon fiber showed considerable advantages in terms of the workability of concrete and the plastic shrinkage cracking reduction of concrete compared with polypropylene fiber and cellulose fiber.

• 한국주조공학회지
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• 제33권3호
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• pp.113-121
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• 2013

The effects of Zn and Mg amounts on the solidification characteristics, microstructure, thermal conductivity and tensile strength of Al-Zn-Mg-Fe alloys were investigated for the development of high thermal conductivity aluminium alloys for die casting. Zn and Mg amounts in Al-Zn-Mg-Fe alloys had a little effect on the liquidus / solidus temperature, the latent heat for solidification and the fluidity of Al-Zn-Mg-Fe alloys. Thermo-physical modelling of Al-Zn-Mg-Fe alloys by JMatPro program showed $MgZn_2$, AlCuMgZn and Al3Fe phases on microstructure of their alloys. Increase of Zn and Mg amounts in Al-Zn-Mg-Fe alloys resulted in gradual reduction of the thermal conductivity of their alloys. Increase of Mg amounts in Al-2%Zn-Mg-Fe alloys had little effect on the tensile strength of their alloys, but increase of Mg amounts in Al-4%Zn-Mg-Fe alloys resulted in steep increase of the tensile strength of their alloys.

• 한국구조물진단유지관리공학회 논문집
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• 제26권4호
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• pp.11-19
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• 2022

본 연구에서는 기계식 커플러의 이음성능을 향상시키기 위해 다른 접합방식을 가진 두 가지의 새로운 커플러를 개발하였다. 두 가지 방식의 기계식 이음장치에 대하여 응력 해석을 수행하였다. 커플러의 재료특성, 접합방식, 내부 조임쇠의 경사길이를 변수로 최대 인장강도의 영향성을 분석하기 위해 일축인장시험을 수행하였다. 일축인장시험결과를 만족하는 시험체를 대상으로 KS D 0249에 의거하여 정적내력시험 및 반복하중 시험을 수행하였다. 이에 대한 연구결과는 다음과 같다. (1) 커플러의 인장강도와 내부 조임쇠의 경사길이는 최대 인장강도에 영향을 끼친다. (2) 연결 방식에 따라 접합된 철근의 강성, 슬립량, 강성감소율에 영향이 있다. 연구결과는 새롭게 제안된 향상된 기계식 이음장치의 현장 적용에 대한 가능성을 검증하였다.

• 한국해양공학회지
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• 제25권3호
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• pp.66-72
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• 2011

This is the fourth of a series of companion papers dealing with the mechanical property reductions of various marine structural steels. Even though a reduction of the elastic modulus according to temperature increases has not been obtained from experiments, high temperature experiments from room temperature to $900^{\circ}C$ revealed that initial the yield strength and tensile strength are both seriously degraded. The mechanical properties obtained from high temperature experiments are compared with those from EC3 (Eurocode 3). It is found that the high temperature test results generally comply with the prediction values by EC3. Based on the prediction of EC3, time domain nonlinear finite element analyses were carried out for a blast wall installed on a real FPSO. After applying the reduced mechanical properties, corresponding to $600^{\circ}C$ to the FE model of the blast wall, more than three times the deflections were observed and it was observed that most structural parts experience plastic deformations exceeding the reduced yield strength at the high temperature. It is noted that a protection facility such as PFP (passive fire protection) should be required for structures likely to be directly exposed to fire and explosion accident.