• 한국지진공학회논문집
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• 제27권2호
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• pp.119-127
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• 2023

In this paper, seismic performance evaluation was carried out for eight circular reinforced concrete columns designed seismically by KRTA[1]and KCI[8]. Primary design parameters for such columns included many longitudinal reinforcements, yield strength of reinforcements, the vertical spacing of spirals, aspect ratio, and axial force ratio. The test results showed that all the columns exhibited stable hysteretic and inelastic responses. Based on the test results, drift ratios corresponding to each damage state, such as initial yielding, initial cover spalling, initial core concrete crushing, buckling, and fracture of longitudinal reinforcement and final spalled region, were evaluated. Then, those ratios were compared with widely accepted damage limit states. The comparison revealed that the existing damage states were considerably conservative. This implies that additional research is required for the damage limit states of such columns designed seismically by current Korean design codes.

• 한국응용곤충학회지
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• 제45권3호
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• pp.327-331
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• 2006

벼 혹명나방 유충이 벼에 주는 피해를 해석하기 위해 유충 마리당 가해엽수를 조사하고, 생육시기별 절엽 수준(0, 10, 30, 50, 70 및 90%)을 달리하여 수량 및 수량구성 요인을 조사한 결과, 유충 1마리가 유충기간 동안 벼 잎을 $6{\sim}7$개 피해를 줄 수 있는 것으로 조사되었다. 출수전(유수분화기)에는 절엽률과 등숙률과는 Y = -9.379X + 83.630 ($R^{2}=0.493$), 절엽률과 수량감소율과는 Y = 0.139X + 0.490 ($R^{2}=0.925$), 절엽률과 완전미율과는 Y = -4.880X + 81.116 ($R^{2}=0.665$)의 관계가 있었다. 출수 후(유숙기)에는 절엽률과 등숙비율과는 Y = -23.0l4X + 83.589 ($R^{2}=0.915$), 절엽률과 수량 감소율과는 Y=0.141X + 3.466 ($R^{2}=0.842$), 피해율과 완전미율과는 Y = -13.795X + 81.964 ($R^{2}=0.898$) 관계가 있었다. 따라서 출수전보다 출수 후가 혹명나방 피해를 받았을 때 수량이나 수량구성요소에 더 큰 영향을 준 것으로 조사되었다. 벼 혹명나방 피해허용수준은 출수 전(유수분화기)에는 피해엽률 30%, 출수 후 (유숙기)에는 피해엽률 7%였다.

• 한국유기농업학회지
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• 제19권spc호
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• pp.267-270
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• 2011

Root-knot nematodes cause a significant damage on fruit yield and quality of green house growing crops. To asses the effect of eggplant rootstock, Torvum vigor', TaibyouVF' and 'Daitaro' were grafted on eggplants(Solanum melongena cv. Chookyang) and planted in root-knot nematode infested microplot in green house and compared their fruit yield, quality and plant growth with non-grafted control. Eggplant grafted with Torvum vigor had the highest fruit yield and top growth and followed by Daitaro. Non-grafted eggplant had lower yield but had higher root weight because of heavy root-knot nematode infection. Rootstock grafting in eggplant farming is a good alternative technique in root-knot nematode infested green houses without compromising fruit yield and can be applied instantly as organic farming practice.

• 한국세라믹학회지
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• 제35권7호
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• pp.671-678
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• 1998

Hertzian indentation tests with sphere indenters were used to study the mechanical properties of glass-in-filtrated alumina and spinel composites and evaluated the effect of preform microstructure and evaluated the effect of preform microstructure and glass con-tents on contanct damage and strength. The spinel composite showed more brittle behavior than the alumina composite which is verified from indentation stress-strain curve cone cracks and quasi-plastic deformation developed at subsurface. Failure originated from either cone cracks(brittle mode) or deformation zone(quasi-plastic mode) above critical load for cracking(Pc) and yield ({{{{ {P }_{Y } }}) with the brittle mode more dominant in the spinels and the quasi-plastic mode more dominant in the aluminas. Even though brittle mode was dominant in the spinel composites the strength degradation from accumulation of damage above these critical loads was conspicuously small suggesting that the glass-infiltrated composites should be highly damage tolerant to the blunt contacts.

• Steel and Composite Structures
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• 제3권4호
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• pp.231-242
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• 2003

This paper deals with the formulation and development of fracture criteria for high-strength structural members containing surface damage in the form of notches (i.e., blunt defects). The important role of the yield strength of the material and its strain hardening capacity (evaluated by means of the constitutive law or stress-strain curve) is analysed in depth by considering the fracture performance of notched samples taken from high-strength steels with different levels of cold drawing (the most heavily drawn steel being commercial prestressing steel used in prestressed concrete). The final aim of the paper is to establish fracture-based design criteria for structural members made of steels with distinct yield strength and containing very different kinds of notch-shape surface damage.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2003년도 춘계학술대회논문집
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• pp.254-257
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• 2003

The modified yield function of Gologanu-Leblond-Devaux in conjunction with the Barlat and Lian's yield criterion is studied to clarify the plastic deformation characteristic of voided anisotropic sheet metals. The void growth of an anisotropic sheet under biaxial tensile loading and damage effect of void growth on forming limits of sheet metals are investigated. Also, the shape parameter defining non-spherical(prolate ellipsoidal) voids with initially random orientations is introduced in M-K model. The predicted forming limits are compared with the published experimental data.

• Journal of the Korean Wood Science and Technology
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• 제25권2호
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• pp.75-80
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• 1997

This research has been examined to measure the degree of the fiber damage of ozonenation high yield pulp in the beating process. Ozone treated the TMP(Thermomechanical Pulp) and CTMP(Chemithermomechanical Pulp) of spruce and the CTMP of birch has been beaten to be reached 200ml(freeness) of its content. It had been studied the forming of fiber distribution by treatment for long fiber, short fiber, fine with the above method. As ozone treatment time gets longer, the pulp has showed the tendency of increasing the fiber content of 28, 48mesh. Ozone treated fiber has been increased long fiber content by being added softness. By given longer ozone treatment time, the TMP and CTMP of spruce has showed the decreasing of fiber content. On the contrary, CTMP of birch has showed the increasing its fiber content. It had proved that the results of difference are rather closer to the species of tree than closer to the kinds of pulp. The fiber content of over 200mesh which has created in beating process demonstrates the decreasing of its fiber content by getting longer ozone treatment time. The softness of fiber can be extracted by the lignin of fiber surface that had been formed by ozone treatment. Thus we assume that the fiber in the process of beating obtains less physical damage.

• Steel and Composite Structures
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• 제44권3호
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• pp.325-337
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• 2022

In this research, an earthquake-resistant structural system consisting of a pin-connected steel frame and a bracing with metallic fuses is proposed. Contrary to the conventional braced frames, the main structural elements are deemed to remain elastic under earthquakes and the seismic energy is efficiently dissipated by the damper-braces with an amplification mechanism. The superiority of the proposed damping system lies in easy manufacture, high yield capacity and energy dissipation, and an effortless replacement of damaged fuses after earthquake events. Furthermore, the stiffness and the yield capacity are almost decoupled in the proposed damper-brace which makes it highly versatile for performance-based seismic design compared to most other dampers. A special attention is paid to derive the theoretical formulation for nonlinear behavior of the proposed damper-brace, which is verified using analytical results. Next, a direct displacement-based design procedure is provided for the proposed system and an example structure is designed and analyzed thoroughly to check its seismic performance. The results show that the proposed system designed with the provided procedure satisfies the given performance objective and can be used for developing highly efficient low-damage structures.

• 한국작물학회지
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• 제33권2호
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• pp.195-200
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• 1988

벼를 보통기에 동일하게 이앙하여 추앙후 20일, 유전형성기, 감수분열기 및 출수기의 생육시기별로 포장상태에서 3일간씩 관수처리한 경우와 품종, 이앙기 및 재배조건이 다양한 농가포장에서 태풍 'Thelma 호'('87년 7월 16~18일)에 의해 3일간 관수된 경우에 생육단계별 피해상태와 피해주의 고립분얼이삭의 발생에 의한 수량 보상력을 검토한 결과는 다음과 같다. 1. 보통기 이앙된 벼의 생육시기별 관수처리에서는 생육이 진전될수록 관수된 수온이 높아져 피해가 컸으나 고온기에 여러 생육단계를 갖는 농가포장이 일시에 관수되면 어린 생육단계일수록 피해가 컸다. 2. 생식생장 관수 피해수의 수량보상은 고립절분얼이삭에 의존하였고 고립절분얼이삭이 9월 15일 출수되어 등숙적산온도가 69$0^{\circ}C$, 등숙일조시간이 210시간이 확보되었을 때 쌀 230kg/10a을 보상하였다.0a을 보상하였다.

• 한국작물학회지
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• 제34권1호
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• pp.14-22
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• 1989

벼 잎집무늬마름병에 대하여 저항성반응이 다른 품종을 시험하여 병균접종구, 자연구 및 약제방제구를 두어 병 발생에 의한 수량감소률의 품종간 차이를 2년간에 걸쳐 조사한 결과를 요약하면 다음과 같다. 1. 시험한 품종 중에서 가야벼는 병균접종구나 자연구에서의 발병정도가 가장 낮았으며 태백벼, 관악벼 및 Labelle은 균발생이 심하였고, 약제방제구에서는 병이 거의 발생하지 않았다. 2. 중반저항성품종인 가야벼는 2년간에 걸쳐 병균접종구 및 자연구에서의 수량감소률이 0.3∼5％로 공시품종 중에서 가장 낮았으며 이병성품종인 태백벼는 6.8∼25.8％로 가장 높았고 관아벼와 Labelle도 각각 10％내외의 수량감소률을 보였다. 3. 시험품종의 저항성정도에 관계없이 동일한 품종내에서 잎집무늬마름병의 병반이 지엽까지 진전된 분얼경에서는 등숙비육과 정조천립중이 감소하여 건전경에 비하여 이삭무게가 25％이상 감소하였다. 4. 잎집무늬마름병에 대하여 상위엽으로의 병반진전이 더디게 되었기 때문에 수량감소율이 낮았다.