• 소성∙가공
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• 제15권7호
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• pp.518-523
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• 2006

Wet wire drawing of brass coated steel wire, used for tire reinforcement, is realized with Tungsten Carbide(WC) dies sintered with a cobalt(Co) binder. Dies wear represents an important limitation to the production process and cost savings. Several parameters, such as Co content, WC grain size of tungsten carbide, sintering conditions, and so on, affect on the wear of the drawing die. In this study, the effect of the diamond abrasive particle size on the life of the WC centered dies of the wet wire drawing was investigated. Wet wire drawing experiments were carried out on a wet wire drawing machine. From the experiments, the dies life, dies fracture, wire surface roughness, and wire breaks were investigated. From the results, it was found that the wear of the WC dies increased with the increase in the diamond abrasive particle size.

• 한국분말재료학회지
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• 제10권4호
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• pp.275-280
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• 2003

Synthesis and characteristics of Cu nanopowder were considered by in-situ characterization method using SMPS in pulsed wire evaporation process. With increasing pressure in chamber, particle size and degree of agglomeration increased by increase of collision frequency. Also, it was found from the XRD analyses and BET measurements that crystallite size and particle size decreased with elevating applied voltage. However, SMPS measurements and TEM observation revealed the increase of particle size and degree of agglomeration with increase of applied voltage. These results suggested that particle growth and agglomeration depend on overheating factor in chamber at the early stage and thermal coagulation in filtering system during powder formation until collection.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1992년도 하계학술대회 논문집 B
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• pp.969-972
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• 1992

It is shown that the ac breakdown strength, treeing phenomena, oxidation level, and crystallinity of unaged and aged distribution CV cables vary with XLPE insulations (characterizing anti-oxidation) and curing process. The maximum size of bow-tie tree in insulation influenced on the decrease of ac breakdown strength and the increase of oxidation level and crystallinity of XLPE according to aging time lead to increase the size and density of bow-tie trees.

• 한국분말재료학회지
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• 제12권5호
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• pp.351-356
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• 2005

Nanoscale Al powder with thin layer of alumina was produced by Wire Electric Explosion (WEE) process. Spark-Plasma Sintering (SPS) was performed for the produced powder to confirm the effectiveness of SPS like so-called 'surface-cleaning effect' and so on. Crystallite size and alumina content of produced powder varied with the ratio of input energy to sublimation energy of Al wire ($e/e_s$): Increase in ($e/e_s$) resulted in the decrease of crystallite size and the increase of alumina content. Shrinkage curve during SPS process showed that the oxide surface layer could not be destroyed near the melting point of Al. It implied that there was not enough or no spark-plasma effect during SPS for Al/Alumina powder.

• 로봇학회논문지
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• 제16권2호
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• pp.164-171
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• 2021

This paper proposes a continuum mechanism for manually controlled endoscopic surgical instruments. The wire-driven mechanism is typically adapted for endoscopic surgical tools because motors cannot be embedded to the joints due to the size limitation. However, the conventional wire-driven mechanism has inherent problems caused by redundancy, such as deflection and low precision. It does not have operating force and manipulability for surgery. Therefore, a method to increase the force of the continuum mechanism using a multi-wire with simple mechanical structure is proposed. Moreover, for intuitive operation, a hand-controller mechanism that can manipulate the length of the wire without complex process is proposed. Finally, we show that the proposed mechanism and methods are applicable to endoscopic surgical tools through simple experiments.

• 대한치과교정학회지
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• 제45권1호
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• pp.13-19
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• 2015

Objective: This study aimed to compare the frictional force (FR) in self-ligating brackets among different bracket-archwire angles, bracket materials, and archwire types. Methods: Passive and active metal self-ligating brackets and active ceramic self-ligating brackets were included as experimental groups, while conventional twin metal brackets served as a control group. All brackets were maxillary premolar brackets with 0.022 inch [in] slots and a $-7^{\circ}$ torque. The orthodontic wires used included 0.018 round and $0.019{\times}0.025$ in rectangular stainless steel wires. The FR was measured at $0^{\circ}$, $5^{\circ}$, and $10^{\circ}$ angulations as the wire was drawn through the bracket slots after attaching brackets from each group to the universal testing machine. Static and kinetic FRs were also measured. Results: The passive self-ligating brackets generated a lower FR than all the other brackets. Static and kinetic FRs generally increased with an increase in the bracket-archwire angulation, and the rectangular wire caused significantly higher static and kinetic FRs than the round wire (p < 0.001). The metal passive self-ligating brackets exhibited the lowest static FR at the $0^{\circ}$ angulation and a lower increase in static and kinetic FRs with an increase in bracket-archwire angulation than the other brackets, while the conventional twin brackets showed a greater increase than all three experimental brackets. Conclusions: The passive self-ligating brackets showed the lowest FR in this study. Self-ligating brackets can generate varying FRs in vitro according to the wire size, surface characteristics, and bracket-archwire angulation.

• 한국대기환경학회지
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• 제15권1호
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• pp.33-39
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• 1999

This study has been performed to develop an efficient electrocharged scrubber. To improve collection efficiency of the scrubber, electric-charger was installed at the forefront of the packed crossflow scrubbers, and an experiment of changing discharge electrode shape and fluctuating electric field strength was undertaken. After using a light-oil boiler for generation of particles in the about 80% weight of submicron size particles was exhausted. Collection characteristics of the electrocharged scrubber were similar to those of two-stage electrostatic precipitator. In this study the collection efficiency of submicron size particles has been much improved, compared with the previous ones. In an experiment of changing discharge electrode and electric field strength, a needle-spike shape wire electrode showed a higher collection efficiency than round shape wire. The collection efficiency becomes increased with an increase of electric field strength.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 춘계학술대회논문집D
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• pp.232-239
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• 2001

The present study is an experimental investigation of nucleate boiling heat transfer mechanism in pool boiling from wire heaters immersed in saturated FC-72 coolant and water. The vapor volume flow rate departing from a wire during nucleate boiling was determined by measuring the volume of bubbles, varying $25{\mu}m,\;75{\mu}m,\;and\;390{\mu}m$, from a wire utilizing the consecutive-photo method. The effects of the wire size on heat transfer mechanism during a nucleate boiling were investigated by measuring vapor volume flow rate and the frequency of bubbles departing from a wire immersed in saturated FC-72. One wire diameter of $390{\mu}m$ was selected and tested in saturated water to investigate the fluid effect on the nucleate boiling heat transfer mechanism. Results of the study showed that an increase in nucleate boiling heat transfer coefficients with reductions in wire diameter was related to the decreased latent heat contribution. The latent heat contribution of boiling heat transfer for the water test was found to be higher than that of FC-72. The frequency of departing bubbles was correlated as a function of bubble diameters.

• Earthquakes and Structures
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• 제26권5호
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• pp.363-382
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• 2024

In India's north-eastern region, low-strength autoclaved aerated concrete (AAC) blocks are widely used for constructing masonry structures, making them susceptible to lateral forces due to their low tensile and shear strengths and brittleness nature. The absence of earthquake-resistant attributes further compromises their resilience during seismic events. An economically viable solution to enhance the structural integrity of these masonry structures involves integrating steel wire mesh within the masonry mortar joints. This study investigates the in-plane shear behaviour of AAC masonry by employing two approaches: incorporating steel wire mesh within the masonry bed joint "BJ" and the masonry bed and head joint "BHJ". These approaches aim to augment strength and ductility, potentially serving as earthquake-resistant attributes in masonry structures. Three distinct variations of steel wire mesh and three reinforcing arrangements, i.e. (-), (L) and (Z) arrangement were employed to reinforce the two approaches. The test result reveals a significant enhancement in structural performance upon inclusion of steel wire mesh in both reinforcing approaches, with the "BHJ" approach outperforming the "BJ" approach and the unreinforced masonry, along with increase in capacity as the wire mesh size increases. Furthermore, the effectiveness of the reinforcing arrangement is ranked with the (Z) arrangement showing the largest performance, followed by the (L) and (-) arrangement.

• 대한치과교정학회지
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• 제31권4호
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• pp.467-477
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• 2001

이 연구의 목적은 호선으로 유도되는 치아이동을 실험실에서 실험하는 동안 브라켓과 선재의 운동 마찰저항에 대한 브라켓 수, 브라켓 폭경, 선재 크기가 미치는 영향을 관찰하기 위한 것이다. 상악 제 1, 2소구치, 제 1대구치와 유사한 크기의 레진 치아를 사용하였으며, 치주인대와 탄성계수가 비슷한 폴리 에테르 인상재를 사용하였다. 스테인레스 스틸 트윈 에지와이즈 브라켓으로 좁은 폭경 (2.4 mm), 중간 폭경 (3.0 mm), 넓은 폭경 (4.3 mm)을 사용하였으며, 강선으로는 0.016, 0.018, $0.016\;{\times}\;0.022,\;0.019\;{\times}\;0.025$인치의 굵기를 사용하였고, 결찰은 합성고무링을 이용하고, 제1소구치에 부착된 좁은 폭경 브라켓 1개, 제 1, 2소구치에 부착된 2개의 중간 폭경 브라켓 및 제 1, 2소구치와 제 1대구치에 부착된 3개의 중간 폭경 브라켓과 각 강선 사이의 운동 마찰저항력을 계측하여 다음의 결론을 얻었다. 1. 좁은 폭경, 중간 폭경, 넓은 폭경 세 종류의 브라켓 모두에서 교정용 선재의 단면 크기가 증가할수록 마찰저항력도 증가하였다. 2. 0.016, 0.018인치 원형 강선은 브라켓 폭경이 증가하면 운동마찰저항력은 감소하며, $0.016\;{\times}\;0.022,\;0.019\;{\times}\;0.025$인치 각형 강선은 브라켓 폭경이 증가하면 운동마찰저항력이 증가하는 경향이 있었고0.016인치 원형 강선과 폭경이 다른 브라켓과의 운동마찰저항력 사이에는 통계적으로 유의차가 없었다. 3. 중간 폭경 브라켓의 수가 증가할수록 마찰저항력은 크게 나타났으며, 그 증가율은 브라켓의 수에 비례하였으나 정수배로 증가하지는 않았고 강선의 굵기에 따라 차이가 있었다.