• 콘크리트학회논문집
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• 제12권4호
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• pp.59-67
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• 2000

With increased height of structure, the effect of column shortening need special consideration in the design and construction of high-rise buildings. The shortening of each column affects nonstructural members such as partitions, cladding, and M/E systems, which are not designed to carry gravity forces. The slabs and beams will tilt due to the cumulative differential shortening of adeacent vertical members. The main purpose of estimating the total shortening of vertical structural member is to compensate the differential shortening between adeacent members. This paper presents effect of parameters for phenomenon of column shortening in vertical members. The paper presents effect of parameters for phenomenon of column shortening in vertical members. The conclusions obtained from this study are follow as ; Strength of concrete and steel ratio effected on column shortening caused by elastic and inelastic shortening. Also, it is known that Ultimate-shrinkage-Value, Specific-Creep-Value, and volume to surface ratio effected on inelastic shortening only. Particularly, Ultimate-Shrinkage-Value and Specific-Creep-Value effected considerable on the amount of total column shortening.

• Journal of Korean Neurosurgical Society
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• 제65권6호
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• pp.779-789
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• 2022

Objective : To analyze the effects of the number and shape of fenestrations on the mechanical strength of pedicle screws and the effects of bone cement augmentation (BCA) on the pull-out strength (POS) of screws used in conventional BCA. Methods : For the control group, a conventional screw was defined as C1, a screw with cannulated end-holes was defined as C2, a C2 screw with six pinholes was defined as C3, and the control group type was set. Among the experimental screws, T1 was designed using symmetrically placed thru-hole type fenestrations with an elliptical shape, while T2 was designed with half-moon (HM)-shaped asymmetrical fenestrations. T3 and T4 were designed with single HM-shaped fenestrations covering three pitches and five pitches, respectively. T5 and T6 were designed with 0.6-mm and 1-mm wider fenestrations than T3. BCA was performed by injecting 3 mL of commercial bone cement in the screw, and mechanical strength and POS tests were performed according to ASTM F1717 and ASTM F543 standards. Synthetic bone (model #1522-505) made of polyurethane foam was used as a model of osteoporotic bone, and radiographic examinations were performed using computed tomography and fluoroscopy. Results : In the fatigue test, at 75% ultimate load, fractures occurred 7781 and 9189 times; at 50%, they occurred 36122 and 82067 times; and at 25%, no fractures occurred. The mean ultimate load for each screw type was 219.1±52.39 N for T1, 234.74±15.9 N for T2, 220.70±59.23 N for T3, 216.45±32.4 N for T4, 181.55±54.78 N for T5, and 216.47±29.25 N for T6. In comparison with C1, T1, T2, T3, T4, and T6 showed significantly different ultimate load values (p<0.05). However, when the values for C2 and the fenestrated screws were evaluated with an unpaired t test, the ultimate load value of C2 significantly differed only from that of T2 (p=0.025). The ultimate load value of C3 differed significantly from those of T1 and T2 (C3 vs. T1 : p=0.048; C3 vs. T2 : p<0.001). Linear correlation analysis revealed a significant correlation between the fenestration area and the volume of bone cement (Pearson's correlation coefficient r=0.288, p=0.036). The bone cement volume and ultimate load significantly correlated with each other in linear correlation analysis (r=0.403, p=0.003). Conclusion : Fenestration yielded a superior ultimate load in comparison with standard BCA using a conventional screw. In T2 screws with asymmetrical two-way fenestrations showed the maximal increase in ultimate load. The fenestrated screws can be expected to show a stable position for the formation of the cement mass.

• 콘크리트학회논문집
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• 제12권5호
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• pp.101-110
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• 2000

A practical approach of calculating the ultimate strength of composite beams with unreinforced web opning is proposed through shear behavioral tests. In this method, the slab shear contribution at the opening is calculated as the smaller value of the pullout capacity of shear connector at the high moment end and the one way shear capacity of slab. A simple interaction equation is used to predict the ultimate strength under simultaneous bending moment and shear force. Strength prediction by the proposed method is compared with previous test results and the predictions by other analytical methods. The comparison shows that the proposed method predicts the ultimate capacity with resonable accuracy.

• 대순사상논총
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• 제34집
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• pp.293-321
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• 2020

文化的核心主旨凝結為其價值意涵, 「羽化登仙」集中反映道教文化的終極價值訴求。從文字學視閾探究「羽」, 「化」, 「登」, 「仙」, 有助於我們透視道教神仙信仰這層神秘面紗背後的生命理念, 體知功夫與境界追求, 以及生命修為與精神超越之間特有的內在理路。其中, 「神仙」可謂玄門修士的人生信念, 「羽化」指代其煉養功夫, 「登真」表徵生命能級攀越。「羽化登仙」寓道教文化價值目標, 煉養功夫與生命境界於一體, 乃玄門修士至上價值追求與生命終極鵠的之完美集結。与之相较, 「大巡」「道通真境」, 既主张道人「身心改造」「精神开辟」, 更强调个人修道服务, 服从于「地上天国建设」, 二者统一于「后天仙境」生命价值理想之中。

• 대한치과교정학회지
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• 제22권3호
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• pp.591-602
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• 1992

The purpose of this study was to evaluate the effect of heat treatment on physical properties of 0.016' and 0.016' x 0.022' stainless steel wires. Temperature of heat treatment had intervals of $50^{\circ}C$ from $400^{\circ}C$ to $700^{\circ}C$, and time of heat treatment were 3, 6 and 9 minutes. Tensile tests were measured by ultimate tensile strength and yield strength. Bending tests were assessed by maximum bending force, recovery force, and stiffness. Torsion test was evaluated by torsion cycle until wires were fractured. The results were as follows: 1. In round wires, the highest value of ultimate tensile strength and yield strength were recorded of heat treatment at $500^{\circ}C$. In rectangular wires, the highest value of ultimate tensile strength were after 9 minutes at $400^{\circ}C,\;450^{\circ}C$ and 3, 6 minutes of heat treatment at $50^{\circ}C$, yield strength were the highest value after 3, 6 minutes of heat treatment at $500^{\circ}C$. 2. In both round and rectangular wires, maximum bending force and recovery force were the highest values after 6 minutes of heat treatment at $500^{\circ}C$. In round wires, highest value of stiffness were formed after 9 minutes at heat treatment at $500^{\circ}C$. In rectangular wires, the highest value of stiffness were for 6 minutes in $500^{\circ}C$. 3. In rectangular wires, torsion cycle was minimum after 6 minutes of heat treatment at $500^{\circ}C$. 4. In all of tension, bending, and torsion tests, the heat treated wires were softened over at $700^{\circ}C$. 5. In all of tension, bending, and torsion tests, physical properties of the wires were more influenced by the temperatures than the duration of the heat treatment.

• 한국농공학회지
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• 제30권1호
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• pp.38-49
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• 1988

This paper presented as follows results of laboratory model tests with various shaped footings on soil bed reinforced with the strips on the base of behaviour of soil structure according to the loads and triaxial test results reinforced with geotextiles. Their parameters studied were the effects on the bearing capacity of a footing of the first layer of reinforcement, horizontal and vertical spacing of layers, number of layers, tensile strength of reinforcement and iclination load to the vertical 1.Depending on the strip arrangement, ultimate bearing capacity values could be more improved than urreinforced soil and the failure of soil was that the soil structure was transfered from the macrospace to microspase and its arrangement, from edge to edge to face to face. 2.The reinforcement was produced the reinforcing effects due to controlling the value of factor of one and permeable reinforcement was never a barrier of drainage condition. 3.Strength ratio was decreased as a linear shape according to increment of saturation degree of soil used even though at the lower strength ratio, the value of M-factor was rot influenced on the strength ratio but impermeable reinforcement decreased the strength of bearing capacity. 4.Ultimate bearing capacity under the plane-strain condition was appeared a little larger than triaxial or the other theoretical formulars and the circular footing more effective. 5.The maximum reinforcing effects were obtained at U I B=o.5, B / B=3 and N=3, when over that limit only acting as a anchor, and same strength of fabric appeared larger reinforcing effects compared to the thinner one. 6.As the LDR increased, more and more BCR occurred and there was appeared a block action below Z / B=O.5, but over the value, decrement of BCR was shown linear relation, and no effects above one. 7.The coefficient of the inclination was shown of minimum at the three layers of fabrics, but the value of H / B related to the ultimate load was decreased as increment of inclination degree, even though over the value of 4.5 there wasn't expected to the reinforcing effects As a consequence of the effects on load inclination, the degree of inclination of 15 per cent was decreased the bearing capacity of 70 per cent but irnproved the effects of 45 per cent through the insertion of geotextile.

• Structural Engineering and Mechanics
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• 제66권3호
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• pp.305-315
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• 2018

Interaction of lateral loading, combined with axial force needs to be determined with care in reinforced concrete (RC) one-dimensional structural members (1D SMs) such as beam-columns (BCs) and columns. RC 1D SMs under heavy axial loading are known to fail by brittle mode and small lateral displacements. In this paper, a macro element-based algorithm is proposed to analyze the RC 1D SMs under monotonic or cyclic combined loading. The 1D SMs are discretized into macro-elements (MEs) located between the critical sections and the inflection points. The critical sections are discretized into fixed rectangular finite elements (FRFE). The nonlinear behavior of confined and unconfined concretes and steel elements are considered in the proposed algorithm. The proposed algorithm has been validated by the results of experimental tests carried out on full-scale RC structural members. The evolution of ultimate strain at extreme compression fiber of a rectangular RC section for different orientations of lateral loading shows that the ultimate strain decreases with increasing the axial force. In the examined cases, this ultimate strain ranges from 0.0024 to 0.0038. Therefore, the 0.003 value given by ACI-318 code for ultimate strain, is not conservative and valid for the combined load cases with significant values of axial force (i.e. for the axial forces heavier than 70% of the ultimate axial force).

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2020년도 가을 학술논문 발표대회
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• pp.133-134
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• 2020

The equation of end bearing capacity is applied differently depending on the type of pile, construction method, and load characteristics considering the construction standards. The bearing capacity equation of the design standard is presented in various ways according to the design conditions such as construction method and ground condition, etc. but, It does not reflect the ground strength according to the SPT-N value of weathered rock. This study analyzed the trend of allowable tip bearing capacity by pile diameter through about 480 dynamic loading tests conducted for the construction/quality management of piles for the last 6 years since 2015. The equation for the ultimate end bearing capacity per unit area according to the SPT-N value is presented. The proposed formula of ultimate end bearing capacity per unit area can be applied in the range of 15,000kN/m2 to 30,000kN/m2. The proposed formula, which complements the existing formula, enables pile design and construction/quality management.

• 한국안광학회지
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• 제13권3호
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• pp.29-34
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• 2008

목적: 본 연구에서는 HEMA(2-Hydroxyethyl methacrylate)/Silicone 기본 조합에 각각 BMA(Butyl methacrylate)와 MMA(Methyl methacrylate)를 혼합하여 콘택트렌즈의 재료로 사용한 후, 각각의 물리적 특성을 비교하였다. 방법: 캐스트 몰드 법을 이용하여 각각의 렌즈를 제조 하였으며, 각 시료의 물리적 특성에 대한 평균값을 사용하여 분석하였다. 결과: HEMA/silicone/BMA 조합의 경우, 함수율은 24.69%에서 29.26%, 인장강도는 0.109 kgf에서 0.263 kgf의 분포를 나타내었다. HEMA/silicone/MMA 조합의 경우, 팽윤율은 13.56%에서 14.83%, 함수율은 25.61%에서 29.33%, 인장강도는 0.107 kgf에서 0.286 kgf의 분포를 나타내었다. 결론: 두 조합은 HEMA/silicone(0.20%~11.50%)의 기본 조합에서 BMA(5.15%)와 MMA(5.15%)를 일정량 첨가한 것으로 두 경우 모두에서 BMA의 양과 MMA의 양이 상대적으로 감소할수록 팽윤율과 함수율이 증가하는 경향을 보였다. HEMA/silicone/MMA 조합의 경우, 인장강도는 silicone의 비율이 증가할수록 4-MMA 시료까지는 다소 증가하는 경향을, HEMA/silicone/BMA 조합의 경우, 인장강도는 silicone의 비율이 증가할수록 감소하는 경향을 나타내었다.

• 한국지반공학회논문집
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• 제24권4호
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• pp.5-13
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• 2008

연약한 실트지반(ML)과 생활오폐수와 공장폐유로 오염된 실트지반($ML_p$)에 실내모형실험을 실시하여 오염물질의 증가에 따른 지지력값의 변화 등에 대한 실제의 적용성을 기존의 연구결과와 비교 분석하였다. 생활오폐수와 공장폐유로 오염된 실트지반은 오염물질 함량이 점차 증대할수록 오염물질의 영향으로 연약한 실트지반 보다 지반의 소성화가 촉진되어 지반의 강도특성은 감소하는 것으로 나타났다. 연약한 실트지반의 한계하중 값 $q_{cr}=4.14c_u$, 극한지지력 값 $q_{ult}=9.53c_u$로 산정되었으며, 생활오폐수와 공장폐유로 오염된 실트지반의 한계하중 값 qcr=1.78cu, 극한지지력 값 $q_{ult}=4.39c_u$로 산정되었다. 생활오폐수와 공장폐유로 오염된 실트지반의 한계하중과 극한지지력 값이 연약한 실트지반의 한계하중과 극한지지력 보다 다소 작게 나타났다. 이는 오염물질의 증가로 인하여 전단저항이 저하되므로써 다소 작은 값을 나타낸 것으로 사료된다.