• Journal of Sensor Science and Technology
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• v.31 no.6
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• pp.383-388
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• 2022

Currently, photodetectors are being extensively studied and developed for next-generation applications, such as in autonomous vehicles and image sensors. In this regard, all-inorganic metal halide perovskite (CsPbX₃; X = Cl, Br, and I) nanocrystals (NCs) have emerged as promising building blocks for various applications owing to their high absorption coefficients, tunable bandgaps, high defect tolerances, and solution processability. These features, which are typically required for the development of advanced optoelectronics, can be engineered by modifying the chemical compositions and surface chemistry of the NCs. Herein, we briefly review various strategies adopted for the application of CsPbX₃ perovskite NCs in photodetectors and for improving device performance. First, modifications of the chemical compositions of CsPbX₃ NCs to tune their optical bandgaps and improve the charge-transport mechanism are discussed. Second, the application of surface chemistry to improve oxidation resistance and carrier mobility is described. In the future, perovskite NCs with prospective features, such as non-toxicity and high resistance to external stimuli, are expected to be developed for practical applications.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.26 no.3
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• pp.679-691
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• 2016

As vehicle started to contain many different communication devices, collecting external information became possible in IoT environment. In such environment, remotely controling vehicle is possible when vehicle information is obtained by looking in to vehicle network through smart device. However, android based smart device applications are vulnerable to malicious modulation and redistribution. Modulated android application can lead to vehicle information disclosure that could bring about vehicle control accident which becomes threat to drivers. furthermore, since vehicles today does not contain security methods to protect it, they are very vulnerable to security threats which can cause serious damage to users and properties. In this paper, many different vehicle management android applications that are sold in Google Play has been analyzed. With this information, possible threats that could happen in vehicle management applications are being analysed to prove the risks. the experiment is done on actual vehicle to prove the risks. Also, access control method to protect the vehicle against malicious actions that could happen through external network in IoT environment is suggested in the paper.

• Journal of KIISE:Computer Systems and Theory
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• v.35 no.8
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• pp.378-384
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• 2008

Many embedded systems are supporting Java as their software platform via Java virtual machine. Java virtual machine manages memory automatically by providing automatic memory management, i.e. garbage collector. Because only scarce memory is available to embedded system, Java virtual machine should use small memory and manage it efficiently. This paper introduces two memory management techniques to exploit small memory in Java virtual machine which can execute multiple Java applications concurrently. First, compaction based garbage collection is introduced to overcome external fragmentation problem in presence of immovable memory area. Then garbage collector driven class unloading is introduced to reduce memory use of unnecessary loaded classes. We implemented these techniques in working embedded system and observed that they are very efficient, since more Java applications are able to be executed concurrently and memory use is also reduced with these techniques.

• Korean Journal of Oriental Medicine
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• v.13 no.3
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• pp.1-10
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• 2007

This study is on the characteristics of LiSangSockDanBang(理傷續斷方). Through this study, the characteristics of LiSangSockDanBang(理傷續斷方) can be oganized as the following: First of all, in LiSangSockDanBang, the treatment of traumatic injury is consisted of the fourteen steps. This fourteen steps is resorted by four steps. ; Washing(洗藥法), Standin in line(整復法), Using an external application(外治法), Using an internal medicine(內服法). This is LiSangSockDanBang's major characteristics. Because of this contents, LiSangSockDanBang is quoted on EuiBangLyuChi(醫方類聚). The first treatment of traumatic injury is Wahing. Wahing is not only sterilizing a wounded region but pushing out the PungSa(風邪). So, to avoid a infection of a tetanus, washing medicine consist of the herbs, that push out the PungSa(風邪). LiSangSockDanBang has high level of surgery. In 1456, YoungLyuGumBang(永類鈐方), has no more level than surgery's in LiSangSockDanBang, is reprinted. This fact means that the surgery is used frequently in those days. In this scientific backing, an operation needle, that described in ChiJongJiNam(治腫指南) and ChiJongBiBang(治腫秘方), are written by Lim UnGook(任彦國), is used frequently, too. In LiSangSockDanBang, the major external applications are HookLyongSan(黑龍散) and PungLyuSan(風流散). In case of open wound, the HookLyongSan is used but in closed wound, PungLyuSan is used. The internal medicine has three applications. ; Removing extravasated blood(瘀血), Catharsis(通利大小便), Supplementation(補氣血).

• Journal of the Korea Institute of Information and Communication Engineering
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• v.15 no.3
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• pp.632-638
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• 2011

This paper presents on-chip Design-for-Testability (DFT) circuit for radio frequency System-on-Chip (SoC) applications. The proposed circuit measures functional specifications of RF integrated circuits such as input impedance, gain, noise figure, input voltage standing wave ratio (VSWRin) and output signal-to-noise ratio (SNRout) without any expensive external equipment. The RF DFT scheme is based on developed theoretical expressions that produce the actual RF device specifications by output DC voltages from the DFT chip. The proposed DFT showed deviation of less than 2% as compared to expensive external equipment measurement. It is expected that this circuit can save marginally failing chips in the production testing as well as in the RF system; hence, saving tremendous amount of revenue for unnecessary device replacements.

• Wind and Structures
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• v.35 no.1
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• pp.55-66
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• 2022

Tall buildings are often subjected to steady and unsteady forces due to external wind flows. Measurement and mitigation of these forces becomes critical to structural design in engineering applications. Over the last few decades, many approaches such as modification of the external geometry of structures have been investigated to mitigate wind-induced load. One such proven geometric modification involved the rounding of sharp corners. In this work, we systematically analyze the impact of rounded corner radii on the reducing the flow-induced loading on a square cylinder. We perform 3-Dimensional (3D) simulations for high Reynolds number flows (Re=1 × 105) which are more likely to be encountered in practical applications. An Improved Delayed Detached Eddy Simulation (IDDES) method capable of capturing flow accurately at large Reynolds numbers is employed in this study. The IDDES formulation uses a k-ω Shear Stress Transport (SST) model for near-wall modelling that prevents mesh-induced separation of the boundary layer. The effects of these corner modifications are analyzed in terms of the resulting variations in the mean and fluctuating components of the aerodynamic forces compared to a square cylinder with no geometric changes. Plots of the angular distribution of the mean and fluctuating coefficient of pressure along the square cylinder's surface illustrate the effects of corner modifications on the different parts of the cylinder. The windward corner's separation angle was observed to decrease with an increase in radius, resulting in a narrower and longer recirculation region. Furthermore, with an increase in radius, a reduction in the fluctuating lift, mean drag, and fluctuating drag coefficients has been observed.

• Journal of the Korea Society of Computer and Information
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• v.27 no.5
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• pp.149-156
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• 2022

Recently, there have been many reports of document-type malicious code injecting malicious code into Microsoft Office files. Document-type malicious code is often hidden by encoding the malicious code in the document. Therefore, document-type malware can easily bypass anti-virus programs. We found that malicious code was inserted into the Visual Basic for Applications (VBA) macro, a function supported by Microsoft Office. Malicious codes such as shellcodes that run external programs and URL-related codes that download files from external URLs were identified. We selected 354 keywords repeatedly appearing in malicious Microsoft Office files and defined the number of times each keyword appears in the body of the document as a feature. We performed machine learning with SVM, naïve Bayes, logistic regression, and random forest algorithms. As a result, each algorithm showed accuracies of 0.994, 0.659, 0.995, and 0.998, respectively.

• Journal of KIISE:Software and Applications
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• v.33 no.1
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• pp.95-104
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• 2006

The Gradient Vector Flow (GVF) snake or active contour model offers the best performance for image segmentation. However, there are problems in classical snake models such as the limited capture range and the slow progress into concavity. This paper presents a new method for enhancing the performance of the GVF snake model by extending the external force fields from the neighboring fields and using a modified smoothing method to regularize them. The results on a simulated U-shaped image showed that the proposed method has larger capture range and makes it possible for the contour to progress into concavity more quickly compared with the conventional GVF snake model.

• Proceedings of the IEEK Conference
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• 2005.11a
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• pp.877-880
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• 2005

This paper describes a PLL frequency synthesizer for wireless LNA applications. The design is focused mainly on low-power and low-phase noise characteristics. A 128/129 dual-modulus prescaler has been designed using the proposed TSPC D flip-flops for high-speed operation and low-power consumption The designed synthesizer includes all building blocks for elimination of external components, other than the crystal. Its operating frequency can be programmed by external data. The frequency synthesizer has been designed using a $0.25{\mu}m$ CMOS process parameters. It operates in the frequency range of 2GHz to 3GHz and consumes 3.2mA at 2.5GHz from a 2.5V supply.

• IEMEK Journal of Embedded Systems and Applications
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• v.9 no.6
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• pp.323-334
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• 2014

In this paper, we proposed indoor positioning system with improved accuracy. The proposed indoor location measurement system is based pedestrian location measurement method that use the embedded sensor of smartphone. So, we do not need wireless external resources, such as GPS or WiFi signals. The conventional methods measure indoor location by generating a movement route of pedestrian by step and direction recognition. In this paper, to correct the direction sensor error, we use the common feature of the normal indoor floor map that the indoor path is lattice-structured. And we quantize moving directions depending on the direction of indoor path. In addition, we propose moving direction measuring method using geomagnetic sensor and gyro sensor to improve the accuracy. Also, the proposed step detection method uses angle and accelerometer sensors. The proposed step detection method is not affected by the posture of the smartphone. Direction errors caused by direction sensor error is corrected due to proposed moving direction measuring method. The proposed location error correction method corrects location error caused by step detection error without the need for external wireless signal resources.