• 한국기계가공학회지
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• 제13권3호
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• pp.15-21
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• 2014

The utilization range of mobile devices is becoming broader than before due to the rapid development of the mobile market. Furthermore, the demands for computer-aided management are increasing due to the extensive expansion of the installation of solar street lights. In this paper, we propose a system which can be used to observe solar street lights. The manager of the system can control and manage the solar street lights using video images on a mobile device.

• 비파괴검사학회지
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• 제25권6호
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• pp.451-458
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• 2005

The effects of fiber orientation on acoustic emission(AE) characteristics have been studied for various composite laminates. Reflection and transmission optical microscopy were used to investigate the damage zone of specimens. AE signals were classified through short time Fourier transform(STFT) as different types: AE signals with a high intensity and high frequency band were due to fiber fracture, while weak AE signals with a low frequency band were due to matrix cracking and/or interfacial cracking. Characteristic feature in the rate of hit-events having high amplitudes showed a procedure of fiber breakages, which expressed the characteristic fracture processes of notched fiber-reinforced plastics with different fiber orientations. As a consequence, the behavior of fracture in the continuous composite laminates could be monitored through nondestructive evaluation(NDE) using the AE technique.

• 한국정밀공학회지
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• 제20권6호
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• pp.214-221
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• 2003

Tension mask assembly is positioned right behind the glass-made front panels of CRT type display devices. The frame-supported thin metal sheet contains numerous slits, through which electron beams are focused to enhance definition. Pretension is imposed on the masks, especially for enlarged flat screens, in order to avoid vibration due to acoustic or mechanical impact. High temperature assembly process subsequent to pretensioning, however, degenerates the creep resistance of common mask materials, and if tensile stress is high enough, tension on the mask may be loosened substantially due to creep deformation. In this study, the assembly is modeled as a combined structure of beams and wire array, and a numerical simulation is attempted for pretensioning followed by high temperature process. According to a model study, small amount of creep strain is likely to be generated, but its adverse influence is not negligible. Some structural modification measures to reduce the creep-induced tension loosening are proposed and evaluated. Also, optimal configuration of frame structure is sought for, which maintains high tension of masks and minimizes the possible creep of frame simultaneously.

• 전자공학회논문지A
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• 제32A권5호
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• pp.54-59
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• 1995

We have proposed a novel self-aligned offset gated polysilicon TFTs device without an offset mask in order to reduce a leakage current and suppress a kink effect. The photolithographic process steps of the new TFTs device are identical to those of conventional non-offset structure TFTs and an additional mask to fabricate an offset structure is not required in our device due to the self-aligned process. The new device has demonstrated a lower leakage current and a better ON/OFF current ratio compared with the conventional non-offset device. The new TFT device also exhibits a considerable reduction of the kink effect because a very thin film TFT devices may be easily fabricated due to the elimination of contact over-etch problem.

• 한국기계가공학회지
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• 제19권7호
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• pp.16-21
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• 2020

The structural analyses were conducted with three models of pinion gears connected to the rack gear which is driven by the steering axle at an automobile. Three models 1, 2 and 3 are designed as the different pinion gears due to the vehicle type. The lower the value of maximum stress, the better the durability of model. Model 3 has the best durability among three models. Models 1 and 2 are expected to require the adjustment in order to improve the durability better. By the utilization of this study result, it is thought to apply at designing the pinion gear with durability at the automobile.

• Journal of Korean Neurosurgical Society
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• 제54권4호
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• pp.344-346
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• 2013

A 55-year-old female patient presented with lower back pain and neurogenic intermittent claudication and underwent L3-L4 posterolateral fusion. To prepare the bone fusion bed, the transverse process of L3 and L4 was decorticated with a drill. On the 9th post-operative day, the patient complained of a sudden onset of severe abdominal pain and distension. Abdominal computed tomography revealed retroperitoneal hematoma in the right psoas muscle and iatrogenic right L3 transverse process fracture. Lumbar spinal angiography showed the delayed hematoma due to rupture of the 2nd lumbar artery pseudoaneurysm and coil embolization was done at the ruptured lumbar artery pseudoaneusyrm. Since then, the patient's postoperative progress proceeded normally with recovery of the hemodynamic parameters.

• Maxillofacial Plastic and Reconstructive Surgery
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• 제36권4호
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• pp.168-172
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• 2014

Bilateral coronoid hyperplasia causes painless progressive trismus, resulting from coronoid process impingement on the posterior aspect of the zygomatic bone. The etiology of coronoid hyperplasia is unclear, with various theories proposed. An endocrine stimulus, increased temporalis activity, trauma, genetic inheritance and familial occurrence have all been proposed, but no substantive evidence exists to support any of these hypotheses. Multiplanar reformatting of axial scans and 3-dimensional reconstruction permit precise reproduction of the shape and size of the coronoid and malar structures, and relationships of all structures of the temporal and infratemporal fossae. This case shows remarkably increased mouth opening by coronoidectomy in a patient who complained of trismus due to hyperplasia of coronoid process.

• 한국기계가공학회지
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• 제18권12호
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• pp.22-27
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• 2019

In this study, the flow rate and air resistance pressure were analyzed on models a, b, and c due to the front wing angle of the airplanes. Models a, b, and c have front wing angles of 120°, 100°, and 160°, respectively. The results of the flow analyses showed that the flow rate and air resistance pressure of model c were observed to be higher than models a and b. The airplane model with a larger angle to the front wing is thought to be the best model for flight. This result can be applied to development of the best in-flight airplane.

• 소성∙가공
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• 제8권3호
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• pp.306-312
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• 1999

In the recent sheet metal forming simulations, it increases to adopt the dynamic explicit method for an effective computation and the elastoplastic formulation for stress recovery. It is inevitable in the dynamic explicit method that some noises occur, which sometimes partly spoil results of simulations. This phenomenon becomes severer when complicate contact conditions are included in simulations. In commercial dynamic codes, the concept of contact damping is introduced. However, the formulation process of it is not revealed well. In this paper, a contact damping method is formulated in order for effectively suppressing noises occurring due to complicated contact conditions. This is checked by analyzing a simple sheet metal stamping process (U-draw bending). From the computational results, it is shown that the contact damping can effectively control the noises due to contacts, especially when considering the sheet thickness, and help to develop more reliable internal stress states, which result in more realistic shapes after springbank.

• 반도체디스플레이기술학회지
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• 제2권1호
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• pp.25-29
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• 2003

The fluid flow, mass transfer, heat transfer and film thickness variation during the spin coating process are numerically studied. The model is said to be I-dimensional because radial variations in film thickness, concentration and temperature are ignored. The finite difference method is employed to solve the equations that are simplified using the similarity transformation. In early time, the film thinning is due to the radial convective outflow. However that slows during the first seconds of spinning so the film thinning due to evaporation of solvent becomes sole. The time varing film thickness is analyzed according to the wafer spin speed, the various solvent fraction in the coating liquid, and the various solvent vapor fraction in the bulk of the overlying gas during the spin coating is estimated.