• 한국주조공학회지
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• 제28권6호
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• pp.273-281
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• 2008

Effects of alloying elements on the mechanical properties of hardened and austempered 3.60wt%C - 2.50wt%C ductile cast iron were investigated. Strength and hardness were increased and ductility was decreased as the amount of alloying element increased. The increasing effect of copper addition on the strength was the most pronounced. The strength and hardness were greatly increased and ductility was decreased by hardening. The effect of alloying element on the mechanical properties of the hardened ductile cast iron was not so pronounced due to the high contents of C and Si. The strength and hardness of austempered ductile cast iron were greatly increased, meanwhile the difference of strength from that of hardened one was not so big. The ductility of the former was higher than that of the latter. The strength and ductility of austempered ductile cast iron with 0.25%Mn were the maximum of all Mn added ones. The maximum strength of that was obtained with the addition of 0.80wt%Cu or 2.00wt%Ni along with this amount of Mn added.

• 생물환경조절학회지
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• 제26권4호
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• pp.324-332
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• 2017

본 연구에서는 서로 다른 열전달 특성을 가진 탄소섬유 전기발열체와 경유온풍난방기가 온실 내부의 온습도, 에너지소비, 작물생육 등에 미치는 영향을 분석하기 위해 오이 재배 단동온실에 대한 난방 비교시험을 수행하였다. 전기발열체 온실에서 난방용량이 온실 환경과 난방기 운전에 미치는 영향을 분석하기 위해 온실에 6, 9, 16kW의 전력을 각각 공급한 결과 전기발열체 ON-OFF 주기는 각각 9, 11, 15회로 비례하여 증가하였으며 온실내부 평균온도는 각각 15.2, 15.3, $15.6^{\circ}C$, 평균상대습도는 84, 81, 76%로 나타나 난방 용량이 클수록 온실내부 온도는 높고, 상대습도는 낮게 나타났다. 또한 6, 9kW 가동 시 하부온도가 상부보다 $0.1^{\circ}C$ 높았으며 16kW 가동 시는 상부 평균온도가 하부보다 $0.2^{\circ}C$ 높았다. 전기발열체와 경유온풍난방기의 비교 시험에서는 난방 시 온실상부와 하부의 온도차가 전기발열체 온실이 $0.1{\sim}0.2^{\circ}C$로 경유온풍난방기 온실의 $0.5{\sim}0.6^{\circ}C$보다 작았으며, 온실 상류와 하류의 온도차는 전기발열체 온실이 $0{\sim}0.1^{\circ}C$로 경유온풍난방기 온실의 $1.3{\sim}1.4^{\circ}C$보다 작아 정밀한 온도관리가 가능하였다. 난방기간 동안 사용한 에너지사용량은 경유온풍난방기 온실이 경유 867L를, 전기발열체 온실이 전력량 8,959kWh를 사용하였으며, 난방비용은 각각 607천원과 403천원이 소요되어 전기발열체 온실에서 약 34%의 비용절감 효과가 있었다. 전기발열체 온실의 경우 상대적으로 군락 상하부의 환경관리가 균일하여 초장을 비롯한 전반적 생육상황이 경유온풍난방기 온실보다 좋았으나 통계적으로 유의한 차이는 없었으며, 수확량 역시 전기발열체 온실의 작물군락 하부 온도가 경유온풍난방기 온실보다 $1.3^{\circ}C$ 더 높게 관리되어 4.3% 증수효과가 있었으나 통계적으로 유의한 차이는 없었다. 원예시설의 최적 난방 관리를 위해서는 각 난방기의 열전달 특성에 기초하여 난방기 용량, 배치, 열분배 방법에 대한 설계가 요구되며, 전열선 형태의 난방기 역시 작물형상 및 재배방법을 고려하여 전열선의 개수, 위치, 방열온도 등에 대한 설계가 필요한 것으로 판단되었다.

• 한국지진공학회:학술대회논문집
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• 한국지진공학회 2001년도 춘계학술대회 논문집
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• pp.278-286
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• 2001

The purpose of this paper is to suggest an analytical technique for time history analysis of R/C frame structure using high-strength concrete under seismic loading. Current researches in hysteretic model of structral elements using high-strength concrete are not enough. It is the cause of error that apply hysteretic model of element using normal-strength concrete to the inelastic analysis of high-strength concrete R/C frame structures. In this paper time history analysis using IDARC and DRAIN programs was performed for a 2-bay, 20-story R/C frame structures. Particularly nonlinear dynamic analysis was performed by IDARC program that was applied hysteretic model of structural element using high-strength concrete. centro earthquake 1940 NS waves was used in the analysis and its peak ground accelerations are changed to be 0.12g, 0.25g

• 전기의세계
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• 제27권6호
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• pp.54-57
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• 1978

An analytical investigation has been carried out for the motion of moving element in electro-dynamometer type directional power relay under A.C source. For the more a time dependent kinetic performance of the element can also be deduced for the D.C component in fault current. The results obtained thus for show that, in the relay with stopper, the performance time for the equal D.C and A.C component can be shorten ca. 0.5Hz in comparison with the fact, the performance time exhibits to delay ca. 0.75Hz under the same conditions for the case of the relay without stopper, it appear that these differences of performance times will not give vise any difficultys for the apects of practical case, however, the obtain results can be applicable in the course of the design of the relay.

• 마이크로전자및패키징학회지
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• 제10권3호
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• pp.1-7
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• 2003

잉크젯 헤드의 발열체에 적용하기 위해 $poly-Si/SiO_2/Si$ 다층기판 위에 결정화된 안정한 코발트실리사이드$(CoSi_2)$ 박막을 형성하여 오메가 형태의 발열체를 제작하고 발열체의 구조적 형상과 온도저항계수 등 전기적 특성을 조사, 연구하였다 $(CoSi_2)$ 박막의 형성은 금속 Co 박막을 급속 열처리장치를 이용하여 $800^{\circ}C$에서 20초 동안 질소 분위기에서 열처리하여 실리사이드 박막을 형성하였다. 발열체의 온도 저항계수 값은 약 $0.0014/^{\circ}C$ 값을 얻을 수 있었다. 인가전압 10 V, 주파수 10KHz 및 펄스간격 $1{\mu}s$ 인가시 발열체의 순간전력은 최대 2W를 나타내었다. 반복된 전압인가에 따른 발열체의 피로특성을 조사한 결과 15 V 이하의 전압인가시 $10^8$ 펄스 cycle 까지 저항변화가 거의 없었으나 17 V 인가전압에서는 $10^6$ cycle에서 발열체의 저항이 급격히 증가하였다.

• 한국정보통신학회논문지
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• 제16권4호
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• pp.799-804
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• 2012

시간 정보를 디지털 정보로 변환하기 위한 아날로그 지연소자를 사용하는 시간-디지털 변환회로를 설계하였다. 설계된 회로는 동작 온도가 변화하더라도 안정된 출력을 얻을 수 있도록 설계하였으며, HSPICE 시뮬레이션을 통하여 동적을 확인하였다. 설계된 지연소자는 온도가 $-20^{\circ}C$에서 $70^{\circ}C$까지 변화할 때 상온에 비해 -0.18%-0.126%의 지연시간 변화율을 보였다. 그리고 이를 이용하는 시간-디지털 변환회로에서 온도가 $-20^{\circ}C$에서 $70^{\circ}C$까지 변화하고 디지털 출력 값이 15가 되었을 때의 시간을 비교하면, 상온에 비하여 -0.18%에서 0.12%의 시간차를 보였다. 그러나 온도 변화에 안정화되지 않은 시간-디지털 변환회로의 경우 상온에 비하여 -1.09%에서 1.28%의 시간차를 보였다.

• 한국실내디자인학회논문집
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• 제20권2호
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• pp.72-84
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• 2011

In accordance with an active development, we now enjoy web 2.0 generation centering bilateral participation through the web 1.0 environment mainly providing the offering information and take a step web 3.0 understanding information by itself. The same time of digital technic development, consumption market arrived at market3.0 generation, also passed by market 1.0 and went via market 2.0 based on bilateral participation and understanding. This change have the marketing implement index changed as well. Nowadays, 7C is generalized of making up sensibility, emotion, communication, relationship, customization and interactive built as a major strategy from the day of 3p focused on customer environment, service process and 4P focused on physical quality of product. It isn't that brand and merchandise create life and experience like as past. It is focused on embodiment of a way of life, culture and creative experience from consumers' own. This treatise, therefore, fixes the object as flagship store positively reflecting the change and examine the change of a marketing code element and social factor stimulating customer behavior change. As a condition of this study, It fixes Maslow Motivation Theory as the main index of customer behavior, and 7C as the marketing code. This treatise ultimately studies the index of flagship store discussion based on domestic outdoor brand cases.

• Structural Engineering and Mechanics
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• 제6권7호
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• pp.727-746
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• 1998

Finite element models and numerical results are presented for bending and natural vibration using the unified third-order plate theory developed in Part 1 of this paper. The unified third-order theory contains the classical, first-order, and other third-order plate theories as special cases. Analytical solutions are developed using the Navier and L$\acute{e}$vy solution procedures (see Part 1 of the paper). Displacement finite element models of the unified third-order theory are developed herein. The finite element models are based on $C^0$ interpolation of the inplane displacements and rotation functions and $C^1$ interpolation of the transverse deflection. Numerical results of bending and natural vibration are presented to evaluate the accuracy of various plate theories.

• Structural Engineering and Mechanics
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• 제13권1호
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• pp.53-74
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• 2002

Composites exhibit larger dispersion in their material properties compared to conventional materials due to larger number of parameters associated with their manufacturing processes. A $C^0$ finite element method has been used for arriving at an eigenvalue problem using higher order shear deformation theory for initial buckling of laminated composite plates. The material properties have been modeled as basic random variables. A mean-centered first order perturbation technique has been used to find the probabilistic characteristics of the buckling loads with different edge conditions. Results have been compared with Monte Carlo simulation, and those available in literature.

• 동력기계공학회지
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• 제4권1호
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• pp.68-73
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• 2000

A mixed degree finite element solutions using hierarchical elements are investigated for convergences on a 2-D simple cases. Elements are generated block by block and each block is assigned an arbitrary solution degree. The numerical study showed that a well constructed blocks can increase the convergence and accuracy of finite element solutions. Also, it has been found that for higher order elements, the convergence trends can be deteriorated for smaller mesh sizes. A procedure for a variable fixed boundary condition has been included.