5,871 research outputs found
Gate location design in injection molding of an automobile junction box with integral hinges
No full textPolymers such as polypropylene or polyethylene offer a unique feature of producing an integral or living hinge for automobiles, which can flex over a million times without causing a failure. However, due to increased fluidity resistance at hinges during molding, several defects such as short shot or premature failure can occur with the improper selection of gate locations. In this paper, a design guideline was induced by investigating resin flow patterns depending on several gate positions obtained by numerical analyses of a simple strip with a hinge. The analyses of the simple strip part showed that the resin at the hinge did not flow until the other side of the strip was filled. Once the resin at the hinge did not flow for a long time enough to be solidified, defects such as short shots or hesitation marks formed. For a practical application of the design guideline determined, four gate systems for an automobile junction box were designed. It was found that the properly determined gate location leads to better resin flow and shorter hesitation time. Finally, injection molding tryouts using a mold that was designed by one of the proposed gate systems were conducted. The experiments showed that hinges without defects could be produced by using the designed gate location to assure the induced design guideline to be reasonable. (C) 2003 Elsevier B.V. All rights reserved.This research was supported by the Daegu University Re-Grant, 2002
Precipitation variability in September over the Korean Peninsula during ENSO developing phase
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Time Delay Controller Design for Position Control of Autonomous Underwater Vehicle Under Disturbances
No full textThis paper presents an enhanced time-delay controller (TDC) for the position control of an autonomous underwater vehicle (AUV) under disturbances. A conventional TDC performs well when the involved data acquisition rate is fast. However, in AUV control applications that use a Doppler velocity log (DVL) navigation system, we cannot keep the data acquisition rate sufficiently fast because a DVL sensor generally supplies data at a slow acquisition rate, which degrades the performance of the TDC. To overcome this problem, we propose an integral sliding-mode controller to be supplemented to the conventional TDC to improve the control precision even if the DVL navigation system is in operation. The proposed controller is computationally simple and robust to unmodeled dynamics and disturbances. We performed computer simulations and experiments with the Cyclops AUV to demonstrate the validity of the proposed controller.1149sciescopu
Chosen logistics processes in Škoda JS
No full textThis master thesis deals with the purchase and sale process in Škoda JS company. The aim of this work is to assess whether the setting of the purchase and sale process is met by the company also within a real business case, in compliance with set controls, and whether the degree of perfect delivery is sufficient. In the introduction, the author specifies the basic terms: logistics, logistic chain, customer benefits, information systems in logistics, buying and selling. The following chapter introduces Škoda JS company, including the sphere of its entrepreneurial activity. This chapter also deals with the nuclear power industry. In the crucial chapter, the author describes the process of purchase and sale in Škoda JS company and compares it with a real business case. In conclusion, the author evaluates discrepancies and suggests recommendations to avoid them
An Empirical Study of Prioritizing JavaScript Engine Crashes via Machine Learning
No full textThe early discovery of security bugs in JavaScript (JS) engines is crucial for protecting Internet users from adversaries abusing zero-day vulnerabilities. Browser vendors, bug bounty hunters, and security researchers have been eager to find such security bugs by leveraging state-of-the-art fuzzers as well as their domain expertise. They report a bug when observing a crash after executing their JS test since a crash is an early indicator of a potential bug. However, it is difficult to identify whether such a crash indeed invokes security bugs in JS engines. Thus, unskilled bug reporters are unable to assess the security severity of their new bugs with JS engine crashes. Today, this classification of a reported security bug is completely manual, depending on the verdicts from JS engine vendors. We investigated the feasibility of applying various machine learning classifiers to determine whether an observed crash triggers a security bug. We designed and implemented CRScope, which classifies security and non-security bugs from given crash-dump files. Our experimental results on 766 crash instances demonstrate that CRScope achieved 0.85, 0.89, and 0.93 Area Under Curve (AUC) for Chakra, V8, and SpiderMonkey crashes, respectively. CRScope also achieved 0.84, 0.89, and 0.95 precision for Chakra, V8, and SpiderMonkey crashes, respectively. This outperforms the previous study and existing tools including Exploitable and AddressSanitizer. CRScope is capable of learning domain-specific expertise from the past verdicts on reported bugs and automatically classifying JS engine security bugs, which helps improve the scalable classification of security bugs
Rapid symptom improvement in major depressive disorder using accelerated repetitive transcranial magnetic stimulation
No full textObjective: Repetitive transcranial magnetic stimulation (rTMS) has contributed to increase in the remission rate for patients with major depressive disorder (MDD). However, current rTMS treatment is practically inconvenient because it requires daily treatment sessions for several weeks. Accelerated rTMS treatment is as efficient and safe for MDD patients as conventional rTMS. Methods: Fifty-one patients with MDD participated in this study; they were randomized into accelerated rTMS (n = 21), conventional rTMS (n = 22), and sham-treatment (n = 8) groups. The accelerated and conventional rTMS groups received 15 sessions for 3 days and 3 weeks, respectively. The sham-treatment group received 15 sham rTMS sessions for 3 days. Primary outcome was assessed using self-report and clinician-rated Korean Quick Inventory of Depressive Symptomatology (KQIDS-SR and KQIDS-C, respectively). Adverse effects were monitored using the Frequency, Intensity, and Burden of Side Effects Rating scale. Changes in depressive symptoms were compared among the three groups using mixed model analyses. Results: For the KQIDS-SR score, there was a significant main effect of "time" (F3,47 = 11.05, p < 0.001), but no effect of "group" (F2,47 = 2.04, p = 0.142), and a trend-level interaction effect of "group × time" (F6,47 = 2.26, p = 0.053). Improvement in depressive symptoms, based on the KQIDS-SR score 3 weeks after treatment, was more prominent in the accelerated rTMS group than in the sham-treatment group (p = 0.011). Tolerability was comparable among the three groups. Conclusion: The accelerated rTMS treatment group showed rapid improvement of depressive symptoms compared with the sham-treatment and conventional rTMS treatment groups. Therefore, accelerated rTMS treatment could be a viable option for MDD, with improved accessibility
Enhancement of in-plane magnetic anisotropy in (111)-oriented Co0.8Fe2.2O4 thin film by deposition of PZT top layer
No full textThe CoFe2O4 and Co0.8Fe2.2O4 single layer (CFO) as well as PZT/CoFe2O4 and PZT/Co0.8Fe2.2O4 bilayer thin films were grown using the pulsed laser deposition technique on Pt(111)/Si substrates at 600 degrees C. All films had a perfect (111)-orientation and the degree of orientation of CFO films was improved by the deposition of a PZT top layer. Precision X-ray diffraction analysis (avoiding the shift of peaks due to sample misalignment) revealed that the CFO films on Pt(111)/Si substrate were under an out-of-plane contraction and the deposition of a PZT top layer led to the increase in the out-of-plane contraction. The (111)-oriented CFO single layer films had a strong in-plane magnetic anisotropy as a result of orientation as well as the stress-induced magnetic anisotropy. The magnetic properties of CFO film were altered by the deposition of a PZT top layer leading to the enhancement of in-plane magnetic anisotropy. The enhanced in-plane magnetic anisotropy was more detectable in PZT/Co0.8Fe2.2O4 rather than PZT/CoFe2O4 bilayer film, which could be expected from its higher magnetocrystalline as well as magnetostriction constants.X1133sciescopu
Wafer-level flip chip packages using preapplied anisotropic conductive films (ACFs)
No full textRecently, wafer-level packaging (WLP) has become one of the promising packaging technologies due to its advantages, such as fewer processing steps, lower cost, and enhanced device performance compared to conventional single-chip packaging. Many developments on new WLP design, material, and process have been accomplished according to performance and reliability requirement of the devices to be packaged [11, [2]. For a lower cost, higher performance, and environmentally green packaging process, anisotropic conductive film (ACF) flip chip assembly has been widely used, such as in ultrafine-pitch flat panel display (FPD) and general semiconductor packaging applications, too. However, there has been no previous attempt on the wafer-level flip chip assembly using ACFs. In this paper, wafer-level flip chip packages using preapplied ACFs were investigated. After ACF prelamination on an electroplated An bumped wafer, and subsequent singulation, singulated chips were flip-chip assemble on an organic substrate using a thermocompression bonding method. Au-plated bumps were well assembled on Ni/Au pads of organic substrates. The electrical, mechanical properties and the reliabilities of wafer-level flip chip assemblies (WL-FCAs) were evaluated and compared with conventional ACF flip chip assemblies using the thermocompression method. Contact resistance measurement was performed after thermal cycling, high temperature/humidity, and pressure cooker test. ACF joints between electroplated An bumps and substrate metal pads showed stable contact resistance of 5 mn per a bump, strong bump adhesion, and similar reliability behaviors compared with conventional ACF flip chip joints using a thermocompression bonding. As a summary, new wafer-level packages using preapplied ACFs were successfully demonstrated for flip chip assembly. The new wafer-level packages using preapplied ACFs can be widely used for many nonsolder flip chip assembly applications such as chip-on-board (COB), chip-on-flex (COF), and chip-on-glass (COG)
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