• Journal of electromagnetic engineering and science
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• 제10권3호
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• pp.127-131
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• 2010

In this paper, the problem of electromagnetic transmission via slits in a cavity inside a conducting screen of finite thickness has been considered in the case that the transverse electric(to the slit axis) polarized plane wave is incident on a slit. The problem is solved numerically by the method of moments and the results are compared with those obtained from an equivalent circuit suitable for a case in which the slit width is infinite and the structure is modified to the two partially overlapped conducting planes. It is observed that when the cavity is resonated, the effective slit width reaches its maximum value of $1/\pi$ wavelengths, irrespective of the actual slit width and the incidence angle. When the thickness of the conducting plane is much smaller than the wavelength, the numerical results for the effective slit width(or transmission width) agree well with those obtained from the equivalent circuit, even though the slit is as narrow as the thickness of the conducting plane.

• 한국전자파학회논문지
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• 제19권8호
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• pp.832-836
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• 2008

본 연구에서는 무한 도체판의 좁은 슬릿에 TM 편파된 평면파가 입사되는 경우의 전자기적 결합 문제를 고려 하였다. 등가 회로를 이용하여 공진된 슬릿을 통한 최대 전력 투과 메커니즘을 설명하는데 연구의 주안점을 두었다. 슬릿이 공진되었을 때 좁은 슬릿을 통해 투과된 전력은 슬릿 폭에 무관하게 유효 슬릿 폭 1/pi 파장에 도달되는 전력과 동일함을 보였다. 제안된 구조와 두꺼운 도체 스크린에서의 좁은 슬릿을 통한 최대 전력 투과 현상들의 유사성을 등가 회로의 관점에서 기술하였다. 또한, 공진이 일어났을 때 슬릿에 의한 산란 전력과 슬릿을 통한 투과 전력이 동일함을 확인하였다.

• 한국전자파학회논문지
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• 제21권10호
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• pp.1094-1102
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• 2010

본 논문에서는 두께가 유한한 도체 스크린 내부 캐비티의 슬릿을 통한 전자파 투과 문제를 슬릿 축에 대해 TE 편파된 평면파가 도체 스크린의 슬릿에 입사되는 경우에 대해 고려하였다. 모멘트 방법을 이용하여 슬릿을 통해 투과된 전력을 구하고, 슬릿의 등가 어드미턴스로부터 구성된 등가 회로 방법을 이용하여 계산된 것과 비교하였다. 공진조건 하에서 좁은 슬릿의 유효 슬릿 폭은 실제 슬릿 폭에 무관하게 $1/{\pi}$ 파장이 됨이 확인되었다. 제안된 구조에서의 공진 투과 현상을 캐비티 내부 슬릿의 등가 어드미턴스 변화와 관련하여 설명하였다.

• Earthquakes and Structures
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• 제18권2호
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• pp.215-222
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• 2020

In this paper, slit steel rubber bearing is presented as an innovative seismic isolator device. In this type of isolator, slit steel damper is an energy dissipation device. Its advantages in comparison with that of the lead rubber bearing are its simplicity in manufacturing process and replacement of its yielding parts. Also, slit steel rubber bearing has the same ability to dissipate energy with smaller value of displacement. Using finite element method in ABAQUS software, a parametric study is done on the performance of this bearing. Three different kinds of isolator with three different values of strut width, 9, 12 and 15 mm, three values of thickness, 4, 6 and 8 mm and two steel types with different yield stress are assessed. Effects of these parameters on the performance characteristics of slit steel rubber bearing are studied. It is shown that by decreasing the thickness and strut width and by selecting the material with lower yield stress, values of effective stiffness, energy dissipation capacity and lateral force in the isolator reduce but equivalent viscous damping is not affected significantly. Thus, by choosing appropriate values for thickness, strut width and slit steel damper yield stress, an isolator with the desired behavior can be achieved. Finally, the performance of an 8-storey frame with the proposed isolator is compared with the same frame equipped with LRB. Results show that SSRB is successful in base shear reduction of structure in a different way from LRB.

• 한국안전학회지
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• 제8권4호
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• pp.189-193
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• 1993

Elimination of dangerous points is the most effective method for safety in mechanical equipments. The next effective method is recognized as isolation and/or safe-guarding of dangerous spots from human beings. With progress of mechanical automation technique such as industrial robots, the need for safe-guard-ins is now being enlarged. It is needless to say that when a machine-guard is designed and installed, a comprechensive understanding of human movement is indispensable. But in this country, there is no scientific for those thems, and no one verifield whether it is valid to apply general guideline such as OSHA's to Korean or not. Further, basic anthropometric items for safety reach standards are neither availble nor included in nation-wide anthropometry project. In this research, human anthropometry data of Korean youngsters are analyzed for safety barrier and safety slit width, and compared with guidelines of other countries-Germany, United Kingdom, Japan, and USA. Though they are standards for safety, since they are based upon their own peoples' data, some of them especially foot reach are not not applicable in this country. It should be notified that careful application of numeric value is very important.

• 반도체디스플레이기술학회지
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• 제19권3호
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• pp.30-35
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• 2020

A microlens has been fabricated by various methods such as a thermal reflow, hot embossing, diamond milling, etc. However, these methods require a relatively complex process to control the microlens shape. In this work, we report on a simple and cost-effective method to fabricate a cylindrical microlens (CML), which can diffuse light widely. We have employed a slot-die head with the dual plate (a meniscus guide with a protruded μ-tip and a shim with a slit channel) for coating of a narrow stripe using poly(methyl methacrylate) (PMMA). We have shown that the higher the coating gap, the lower the maximum coating speed, which causes an increase in the stripe width and thickness. The coated PMMA stripe has the concave shape. To make it in the shape of a convex microlens, we have applied the thermal reflow method. When the stripe thickness is small, however, its effect is negligible. To increase the stripe thickness, we have increased the number of repeated coating. With this scheme, we have fabricated the CML with the width of 223 ㎛ and the thickness of 7.3 ㎛. Finally, we have demonstrated experimentally that the CML can diffuse light widely, a feature demanded for light extraction efficiency of organic light-emitting diodes (OLEDs) and suppression of moiré patterns in displays.

• 한국방사선학회논문지
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• 제14권6호
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• pp.733-740
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• 2020

의료종사자의 피폭선량을 줄이기 위한 최근 연구에서, 방사선이 산란될 때 발생하는 광전효과를 이용하여 방사선치료실 입구에서의 선량을 줄이는 방법이 제안되었다. 이 방법은 특히 저에너지 광자에 효과적이기 때문에 본 연구에서는 몬테카를로 시뮬레이션을 이용하여 슬릿형태 구조물의 일반촬영실 산란 엑스선에 대한 차폐성능을 평가하였다. 두께 2 mm, 폭 50 mm, 길이 900 mm인 판을 2 mm 간격으로 수평 적재하는 형태의 슬릿형태 구조물은 알루미늄에 비해 철 또는 납으로 만드는 경우 차폐효과가 뛰어났다. 재질을 철로 한정한 경우 선원과 관심구역 사이에서 결정된 구조물의 설치위치는 차폐효과와 무관했으며, 판의 폭은 차폐효과에 비례했다. 폭 50 mm 철판을 사용한 경우 산란선이 직접 발생하는 바닥 및 환자의 높이를 제외하면 약 99.9% 또는 그 이상의 차폐효과가 있었다.

• 한국작물학회지
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• 제54권4호
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• pp.357-365
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• 2009

본 연구는 립선별기에서 미숙립 선별능력을 높임으로써 도정효율 증진과 완전미율 향상을 꾀하고자 품종특성을 고려한 립선별기 선별체 최적 조건 구명 시험이 수행되었고, 다음과 같은 결과가 얻어졌다. 1. 립선별기의 선별능력은 현미립 두께에 절대적으로 의존되었는데, 조사된 시험재료의 현미 평균 두께는 1.79(농안)-2.16 mm(대립벼1호)의 분포를 보였다. 2. 품종별 차이는 있었으나, 대체적으로 현미의 평균 립두께가 2.08 mm이상일 경우 1.9 mm 선별체, 2.00-2.08 mm 범위일 경우 1.8 mm 선별체, 1.90-2.00 mm 범위일 경우 1.7mm 선별체, 그 이하일 경우 1.7 mm 이하의 선별체가 정립 손실을 최소화하면서(0.1%이내) 완전미율을 향상시킬 수 있는 조건인 것으로 판단되었다. 3. 백미 품위에 미치는 선별체 분리효과는 미숙립 비율이 높은 품종일수록 크게 발휘되었다. 4. 현미선별 체 눈 크기를 0.1 mm씩 증가시킬 경우 품종별로 현미선벌체 통과물중에 정상립이 포함되어 발생되는 정상립 손실율이 0.5% 수준까지는 현미선별체 눈금크기 증가에 따라 미미하게 증가하였으나, 이 눈금 수준이상에서는 선별체 눈금 0.1 mm 증가에 따라 정상립의 손실율이 급격히 증가하는 것으로 보아 정상립 손실율 0.5% 수준의 눈금이나 그 보다 0.05~0.10 mm 아래 눈금의 선별체가 적당할 것으로 생각되었다.

• 천문학회지
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• 제53권5호
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• pp.103-115
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• 2020

We analyze the spatially resolved kinematics of gas and stars for a sample of ten hidden type 1 AGNs in order to investigate the nature of their central sources and the scaling relation with host galaxy stellar velocity dispersion. We select our sample from a large number of hidden type 1 AGNs, which are identified based on the presence of a broad (full width at half maximum ≳1000 km s^-1) component in the Hα line profile and which are frequently mis-classified as type 2 AGNs because AGN continuum and broad emission lines are weak or obscured in the optical spectral range. We used the Blue Channel Spectrograph at the 6.5-m Multiple Mirror Telescope to obtain long-slit data with a spatial scale of 0.3 arcsec pixel^-1. We detected broad Hβ lines for only two targets; however, the presence of strong broad Hα lines indicates that the AGNs we selected are all low-luminosity type 1 AGNs. We measured the velocity, velocity dispersion, and flux of stellar continuum and gas emission lines (i.e., Hβ and [O III]) as a function of distance from the center. The spatially resolved gas kinematics traced by Hβ or [O III] are generally similar to the stellar kinematics except for the inner center, where signatures of gas outflows are detected. We compare the luminosity-weighted effective stellar velocity dispersions with the black hole masses and find that our hidden type 1 AGNs, which have relatively low back hole masses, follow the same scaling relation as reverberation-mapped type 1 AGN and more massive inactive galaxies.

• 대한기계학회논문집B
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• 제27권9호
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• pp.1299-1308
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• 2003

This paper is studied to investigate the effect of slits and swirl vanes on the development of turbulent flow fields in gun-type gas burner with a cone type baffle plate because this gas burner is generally composed of eight slits and swirl vanes. All of turbulent characteristics including mean velocities were measured in the horizontal plane and cross section by using X-type hot-wire probe from hot-wire anemometer system. This experiment is carried out at flow rate 450 l/min in the test section of subsonic wind tunnel. Slits cause the fast jets, and then they have the characteristic that the flow is not adequately spread to radial direction and has long flow length and very small flow velocity distribution in the central part. On the contrary, swirl vanes does not have long enough for adequate flow length to downstream because the rotational flow diffuses remarkably to radial direction. However, the suitable arrangement between slits and swirl vanes causes effective flow width and flow length, and then it promotes fast flow mixing over the entire region including central part to increase turbulence more largely and effectively. Therefore, it is thought as a very desirable design method in gun-type gas burner to locate slits on the outside of swirl vanes.