• Title/Summary/Keyword: through-hole type

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An Experimental Study on the Frequency Characteristics of Hole Tones Generated by a Circular Jet of Low Speed Impinging on a Plate with a Round Hole (저속의 원형분류가 구멍에 충돌할 때 발생한 구멍음의 주파수특성에 관한 실험적 연구)

  • 이동훈
    • Journal of the Korean Society of Manufacturing Technology Engineers
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    • v.6 no.2
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    • pp.34-41
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    • 1997
  • The objective of this study is to investigate experimentally the frequency characteristics of the hole tones generated by a circular jet of low speed impinging on a plate with a round hole. The experimental results about the sound spectrum and the time wave of the hole tone are presented and discussed in relation with the hole type, the jet velocity and the distance of the nozzle-to-plate with a round hole. From the sound spectrum and time wave measurements, it is found that the hole tone is generated not only by an interaction of convected vortices with a round hole but also by a series of vortex shedding from jets passing through a hole. The hole tones generated by a feedback mechanism consist of many frequency stages and also have a hysteresis phenomenon like an edge tone. But the hole tones generated by a series of vortex shedding have nothing with the stage characteristics. The frequencies of hole tones are influenced by the jet velocity, the distance of the nozzle-to-plate with a round hole and the hole type.

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A parametric study on the microscale-hole-type AC PDP

  • Bae, Hyun Sook;Kim, Joong Kyun
    • Journal of Information Display
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    • v.13 no.3
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    • pp.131-137
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    • 2012
  • In some previous studies, the effect of the microcapillary hole structure in the front dielectric layer was introduced. There have not yet been any report, however, on the detailed study on the discharge characteristics of the hole type, and on the optimization of the microscale hole size. In this study, the discharge characteristics of the microscale hole types in the front dielectric layer in plasma display panels were investigated through plasma numerical simulation. The numerical analysis discussed in this work may shed more light on the discharge mechanism. The modification of the structure of microscale holes is expected to improve the driving voltage and luminance, which may have been due to more energetically charged particles and Xe-excited species, which may in turn have been due to an expanded sheath electric field in the vicinity of the microholes.

Study on the Electrode Design for an Advanced Structure of Vertical LED (Via-hole 구조의 n-접합을 갖는 수직형 발광 다이오드 전극 설계에 관한 연구)

  • Park, Jun-Beom;Park, Hyung-Jo;Jeong, Tak;Kang, Sung-Ju;Ha, Jun-Seok;Leem, See-Jong
    • Journal of the Microelectronics and Packaging Society
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    • v.22 no.4
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    • pp.71-76
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    • 2015
  • Recently, light emitting diodes (LEDs) have been studied to improve their efficiencies for the uses in various fields. Particularly in the aspect of chip structure, via hole type vertical LED chip is developed for improvement of light output power, and heat dissipations. However, current vertical type LEDs have still drawback, which is current concentration around the n-contact holes. In this research, to solve this phenomenon, we introduced isolation layer under n-contact electrodes. With this sub-electrode, even though the active area was decreased by about 2.7% compared with conventional via-hole type vertical LED, we could decrease the forward voltage by 0.2 V and wall-plug efficiency was improved approximately 4.2%. This is owing to uniform current flow through the area of n-contact.

Comparison of Square Section Drawings from Circular Billets through Cassette-Roller-Dies and Hole Die (카세트롤러와 홀다이를 이용한 원형소재에서 사각형 단면 인발 비교)

  • Choi J. I.;Han C. H.
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • 2001.10a
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    • pp.208-211
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    • 2001
  • In the drawing from round billet to non-circular section there are two different processes through solid hole die(HD) and the other cassette roller dies(CRD). The CRD process has several cassette type rollers and a billet is able to move through the given gaps between two profiled rollers. The objective of this study is based on the analysis and evaluation of two aforementioned processes using experiments and finite element simulation. In order to simulate the multi-stage drawing process from circular sectioned billet to rounded square section, the finite element analysis is applied to the process using a commercially available DEFORM-3D code. Two types of experimental drawing tests through designed and manufactured dies for pure copper and aluminum alloy are carried out at room temperature. The analysis included comparison of material properties before and after drawing of each process and also provide some useful information by a FEM simulation.

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The Cooling Characteristics for Circular Irradiation Hole under Suppressing Jet Flow at Guide Tube in HANARO (안내관 제트유동 억제시의 하나로 원형 조사공의 냉각특성)

  • Wu S. I.;Park P. C.
    • 한국전산유체공학회:학술대회논문집
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    • 2004.03a
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    • pp.208-213
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    • 2004
  • The HANARO, multi-purpose research reactor, 30 MWth open-tank-in- pool type, is under normal operation since it reached the initial critical in February 1995. The HANARO is planning to produce a fission moly-99 of radio isotopes, a mother nuclide of Tc-99m, a medical isotope and is under developing a target handling tool for loading and unloading it in a circular flow tube (OR-5). A guide tube is extended from the reactor core to the top of the reactor chimney for easily un/loading a target under the reactor normal operation. But active coolant through the core can be quickly raised up to the top of the chimney through the guide tube by jet flow. This paper is described an analytical analysis to calculate the hole size of a orifice inserted in the circular irradiation hole and to study the flow characteristics through the guide tube under reactor normal operation and loading the target. As results, the results show that the hole size of orifice was 31 mm of the inner diameter to suppress the guide tube jet flow and the coolant safely cooled the target of fission moly after inserting the orifice to the flow tube.

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Analytical-numerical formula for estimating the characteristics of a cylindrical NaI(Tl) gamma-ray detector with a side-through hole

  • Thabet, Abouzeid A.;Badawi, Mohamed S.
    • Nuclear Engineering and Technology
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    • v.54 no.10
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    • pp.3795-3802
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    • 2022
  • NaI(Tl) scintillation materials are considered to be one of many materials that are used exclusively for γ-ray detection and spectroscopy. The gamma-ray spectrometer is not an easy-to-use device, and the accuracy of the numerical values must be carefully checked based on the rules of the calibration technique. Therefore, accurate information about the detection system and its effectiveness is of greater importance. The purpose of this study is to estimate, using an analytical-numerical formula (ANF), the purely geometric solid angle, geometric efficiency, and total efficiency of a cylindrical NaI(Tl) γ-ray detector with a side-through hole. This type of detector is ideal for scanning fuel rods and pipelines, as well as for performing radio-immunoassays. The study included the calculation of the complex solid angle, in combination with the use of various points like gamma sources, located axially and non-axially inside the through detector side hole, which can be applied in a hypothetical method for calibrating the facility. An extended γ-ray energy range, the detector, source dimensions, "source-to-detector" geometry inside the side-through hole, path lengths of γ-quanta photons crossing the facility, besides the photon average path length inside the detector medium itself, were studied and considered. This study is very important for an expanded future article where the radioactive point source can be replaced by a volume source located inside the side-trough hole of the detector, or by a radioactive pipeline passing through the well. The results provide a good and useful approach to a new generation of detectors that can be used for low-level radiation that needs to be measured efficiently.

A Study for Improvement of Temperature Distribution in Plunger Surface Cooling (브라운관용 플런저 냉각표면의 온도분포 개선을 위한 연구)

  • Kwak, Kyung-Min;Park, Ji-Yeol;Bai, Cheol-Ho
    • Journal of the Korean Society for Precision Engineering
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    • v.25 no.3
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    • pp.126-133
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    • 2008
  • The main objective of the present study is to achieve linear temperature distribution of cooling surface of plunger. K type thermocouples are attached at the surface of plunger to measure temperature. Nozzle and insulating material are inserted in the pin hole of the plunger for this study. Cooling water flow enters at one nozzle and leaves at three nozzles. Flow through nozzle can be activated in the pin hole, temperature of hot point around hole is decreased. Meanwhile, insulating material blocks off heat transfer, temperature of cold point around hole is increased. By combination of nozzle and insulation, heat transfer of hole is controlled effectively, as result its, temperature of plunger surface shows linear temperature distribution.

Prevent Air-core During Draining with Semi Spherical Mesh (반구형 그물망을 이용한 배수시 생성되는 공기 기둥 억제 연구)

  • Han, Eun-Su;Park, Il-Seouk;Sohn, Chang-Hyun
    • Journal of the Korean Society of Visualization
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    • v.9 no.3
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    • pp.38-43
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    • 2011
  • When draining takes place through an axially located drain port in a cylindrical tank without any prevent, a vortex with an air core occurs. In this study, semi spherical concave and convex meshes with different size inner hole are used to find the air core can suppress. The study is carried out with different values of inner hole of mesh and different install direction of semi spherical mesh using PIV and measured velocity distribution. By providing a mesh, the air core can be prevented, even if the ratio of inner hole of mesh and diameter of cylinder is around 0.66. The experimental results show that a convex mesh type is more effective to suppress the air core generation than a concave mesh type.

Microstructure of TiO2 sensor electrode on nano block copolymertemplates using an ALD (나노 블록공중합체 템플레이트에 ALD로 제조된 센서용 TiO2 박막의 미세구조 연구)

  • Park, Jong-Sung;Han, Jeung-Jo;Song, Oh-Sung;Jeon, Seung-Min;Kim, Hyeong-Ki
    • Journal of Sensor Science and Technology
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    • v.18 no.3
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    • pp.239-244
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    • 2009
  • We fabricated nano-templates by low temperature BCP(block copolymer) process at 180 $^{\circ}C$, then we deposited 10 nm-thick $TiO_2$ layers with ALD(atomic layer deposition) at low temperature of 150 $^{\circ}C$. Through FE-SEM analysis, we confirmed the successful formation of the groove-type(width of crest : 30 nm, width of trough : 18 nm) and the cylinder-type(diameter : 10 nm, distance between hole : 25 nm) templates. Moreover, after $TiO_2$-ALD processing, we confirmed the deposition of the uniform nano layers of $TiO_2$ on the nano-templates. Through AFM analysis, the pitches of the crest-through(in groove-type) and hole-hole(in cylinder-type) were the same before and after $TiO_2$-ALD processing. In addition, we indirectly determined the existence of the uniform $TiO_2$ layers on nano-templates as the surface roughness decreased drastically. We successfully fabricated nano-template at low temperature and confirmed that the three-dimensional nano-structure for sensor application could be achieved by $TiO_2$-ALD processing at extremely low temperature of 150 $^{\circ}C$.