• 산업기술연구
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• 제25권A호
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• pp.39-47
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• 2005

Air void systems in hardened concrete has an important influence on concrete durability such as freeze-thaw resistance, water permeability, surface scaling resistance. Linear traverse method and point count method described at ASTM are the routine analysis of the air void system that have been widely used to estimate the spacing factor in hardened concrete. Recently, many concretes often have a spacing factor higher than the generally accepted $200-250{\mu}m$ limit for the usual range of air contents. This study is proposed to estimate the plane spacing factor by calculation of simplicity. The plane spacing factor need two parameters that are air content and numbers of air voids in the hardened concrete. Those obtained from the standard air-void system analysis of the ASTM C 457. The equation is valid for all values of paste-to-air ratio because the estimation of paste content is unnecessary at the using ASTM C 457. The plane spacing factor yields a similar estimate of the standard spacing factor.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2003년도 봄 학술발표회 논문집
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• pp.553-560
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• 2003

From the analytical standpoint, it is advantageous to consider the behavior of supported walls as plane strain condition. But supported walls constitute geotechnical problems which, in strut terms, are not plane strain cases. These represent differences between the measured and the predicted due to the stiffness and spacing of supported walls and the behavior of discontinuous walls such as solider beams with lagging. This study is to investigate simulations of a system behavior along a horizontal section of walls supported by prefabricated strut. Using a beam column method, relative effects associated with prefabricated strut stiffness and spacing in a systematic behavior were investigated.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1994년도 하계학술대회 논문집 C
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• pp.1530-1532
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• 1994

This paper describes the discharge characteristics of liquid nitrogen for plane-plane, needle-plane electrode at variation of gap spacing at atmospheric pressure. The important results obtained from this study are as follows. (1) Breakdown voltage of $LN_2$ for needle-plane electrode is higher than that of for plane-plane electrode and discharge duration tine is longer with increase of gap spacing at atmospheric pressure. (2) The formation of bubbles by evaporation is observed in spite of non-applying source at atmospheric pressure and the creation of corona confirmed for plane-plane electrode results from the bubbles. (3) The applied voltage-discharge magnitude( V-Q) characteristics of $LN_2$ showed hysteresis and the discharge magnitude decreasing and corona voltage increasing proportional to the pulse per second at atmospheric pressure.

• 소음진동
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• 제8권6호
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• pp.1023-1029
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• 1998

When one attempts to construct a hologram. one finds that there are many sources of measurement errors. These errors are even amplified if one predicts the pressures close to the sources. The pressure estimation errors depend on the following parameters: the measurement spacing on the hologram plane. the prediction spacing on the prediction plane. and the distance between the hologram and the prediction plane. This raper analyzes quantitatively the errors when these are distributed irregularly on the hologram plane The sensor mismatch and inaccurate measurement location. position mismatch. are mainly addressed. In these cases. one can assume that the measurement is a sample of many measurement events. The bias and random error are derived theoretically. Then the relationship between the random error amplification ratio and the parameters mentioned above is examined quantitatively in terms of energy.

• 전기학회논문지
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• 제56권1호
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• pp.161-166
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• 2007

In this paper, two 4$\times$4 rectangular patch array antennas operating at 20 GHz are implemented for the satellite communication. The sixteen patch antennas and microstrip feeding line are printed on a single-layered substrate. The design goal is to achieve high directivity and gain by optimizing design parameters through permutations in element spacing. The spacing between the array elements is chosen to be 0.736$\lambda$. Numerical simulation results indicate that the HPBW(Half-Power Beam Width) of the 4$\times$4 patch array antenna is 18.78 degrees in the E-plane and 18.48 degrees in the H-plane with a gain of 17.18 dBi. Numerical simulations of a 4$\times$4 recessed patch array antenna yield a HPBW of 18.71 degrees in the E-plane and 17.82 degrees in the H-plane with a gain of 19.43 dBi.

• 암석학회지
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• 제25권2호
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• pp.151-163
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• 2016

거창지역의 쥬라기 화강암에서 발달하는 결의 특성을 분석하였다. 3개 면, 3개 결에 대한 평가는 (1) 미세균열의 간격의 빈도수(N), (2) 총 간격(${\leq}1mm$), (3) 평균 간격($S_{mean}$), (4) 평균 간격과 중앙 간격($S_{median}$) 사이의 차이값($S_{mean}-S_{median}$), (5) 간격의 밀도(${\rho}$), (6) 도표의 전체구간에 대한 두 지수 사이의 차이값(${\lambda}_H-{\lambda}_L$), (7) 지수의 평균값(${\lambda}_M$), (8) 지수의 상수의 평균값($a_M$), (9) 최초 교차점 이하의 구간에 대한 두 지수 사이의 차이값(${\lambda}t_H-{\lambda}t_L$), (10) 지수의 평균값(${\lambda}t_M$) 및 (11) 지수의 상수의 평균값($at_M$)과 같은 파라미터를 이용하여 수행하였다. 3개 결 그리고 3개 면에 대한 파라미터의 값 사이의 상관성 분석의 결과는 다음과 같다. (I) 파라미터(1, 2, 7 및 8) 및 (II) 파라미터(3, 4 및 5)의 값은 (I) H(3번 결, (H1 + H2)/2) < G(2번 결, (G1 + G2)/2) < R(1번 결, (R1 + R2)/2) 및 (II) R < G < H의 순서이다. 반면에 3개 면에 대한 상기 두 그룹(I~II)의 파라미터의 값은 역순을 보여준다. 그 외에도, 3개 면에 대한 파라미터 $6({\lambda}_H-{\lambda}_L)$, 파라미터 $9({\lambda}t_H-{\lambda}t_L)$, 파라미터 $10({\lambda}t_M)$ 및 파라미터 $11(at_M)$의 값은 각각 R(1번 면, (G1 + H2)/2) < H(3번 면, (R2 + G2)/2) < G(2번 면, (R1 + H2)/2), H < G < R, H < R < G 및 R < H < G의 순이다. 3개 결에 대한 상기 네 파라미터의 값은 R < H < G, R < H < G, H < G < R 및 H < G < R의 다양한 순을 각각 보여준다. 한편, 두 방향의 도표 사이의 최초 접촉점 및 교차점에 해당되는 간격값을 도출하였다. 3개 결에 대한 상기 간격값은 1번 결(R1 및 R2) < 2번 결(G1 및 G2) < 3번 결(H1 및 H2)의 순이다. 3개 면에 대한 간격값은 1번 면(G1 및 H1) < 3번 면(R2 및 G2) < 2번 면(R1 및 H2)의 순이다. 특히 3개 결과 3개 면에 대한 교차각은 1번 결 및 1번 면 < 3번 결 및 3번 면 < 2번 결 및 2번 면의 순이다. 따라서, 1번 결(R1 및 R2) 및 1번 면(G1 및 H1)의 두 도표는 보다 높은 접촉점 또는 교차점의 빈도수를 보여준다. 이러한 변화 특성은 3개 면 및 3개 결의 종합도를 통하여 도출하였다. 마지막으로, 분포 형태와 함께 파라미터의 값을 통한 상관성 분석은 3개 채석면의 판별에 유용하다.

• Journal of Biosystems Engineering
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• 제36권5호
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• pp.348-354
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• 2011

Various crop spacing methods have been implemented so far for the greenhouse and plant factory applications. However, there is no generally accepted parameter for evaluation of plant spacing efficiency in plant production system. In this study, 'Planted Area Index' (PAI) of a spacing method is defined as the ratio of the planted area in the field to required planted area using the spacing method when no transplanting operation is assumed. Three common types of spacing methods for plane placement of the plants were modeled mathematically. For calculating the planted area, an optimal growth radius function (R(t)) is needed. Function of the days after transplanting stage gives a radius of an optimal circle area for the living plants. A computer simulation was developed to calculate the PAI, based on three crop spacing methods and four optimal growth radius functions. In general, the 1-D zigzag spacing showed the best PAI. Moreover, it gives an example on how to apply the PAI for the design.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1988년도 전기.전자공학 학술대회 논문집
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• pp.756-760
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• 1988

The paper presents the measurement results on the parameters affecting the breakdown mechanism of a large air spacing under switching impulse voltages. Measured parameters are the velocities of leader channels, predischarge currents, electric charges injected into the rod-plane air gap and electric field intensities on the plane. For the 3m air gap under switching impulse voltages, the velocities of leader channel have been measured to be of 1cm/${\mu}s$ - 5cm/${\mu}s$, electric field intensity of 2kv/cm, predischarge current of 1.2A - 1.6A, the charges injected into the air gap of 11 - 40 ${\mu}$C for 400-887kV impulse voltages.

• 대한전기학회논문지
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• 제40권12호
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• pp.1290-1295
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• 1991

The paper presents the measurement results on the parameters affecting the breakdown mechanism of a large air spacing under switching impulse voltages. Measured parameters are the velocities of leader channels, predischarge currents, electric charges injected into the rod-plane air gap and electric field intensities on the plane. For the 3m air gap under switching impulse voltages, the velocities of leader channel have been measured to be of 1cm/x10S0-6Ts - 5cm/x10S0-6Ts, electric field intensity of 2kv/cm, predischarge current of 1.2-1.6A, the charges injected into the air gap of 11-40x10S0-6TC for 400-887kV impulse voltages.

• Earthquakes and Structures
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• 제26권6호
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• pp.489-499
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• 2024

Infill masonry walls are vulnerable to lateral loads, including seismic, wind, and concentrated push loads. Various strengthening metal fittings have been proposed to improve lateral load resistance, particularly against seismic loads. This study introduces the use of post-compressed wedges as a novel reinforcement method for infill masonry walls to enhance lateral load resistance. The resistance of the infill masonry wall against lateral-concentrated push loads was assessed using an out-of-plane push-over test on specimens sized 2,300×2,410×190 mm³. The presence or absence of wedges and wedge spacing were set as variables. The push-over test results showed that both the unreinforced specimen and the specimen reinforced with 300 mm spaced wedges toppled, while the specimen reinforced with 100 mm spaced wedges remained upright. Peak loads were measured to be 0.74, 29.77, and 5.88 kN for unreinforced specimens and specimens reinforced with 100 mm and 300 mm spaced wedges, respectively. Notably, a tighter reinforcement spacing yielded a similar strength, as expected, which was attributed to the increased friction force between the masonry wall and steel frame. The W-series specimens exhibited a trend comparable to that of the displacement ductility ratio. Overall, the findings validate that post-compressed wedges improve the out-of-plane strength of infill masonry walls.