• Korean Journal of Materials Research
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• v.32 no.6
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• pp.287-292
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• 2022

Magnesium-antimonide is a well-known zintl phase thermoelectric material with low band gap energy, earth-abundance and characteristic electron-crystal phonon-glass properties. The nominal composition Mg_3.8-xZn_xSb₂ (0.00 ≤ x ≤ 0.02) was synthesized by controlled melting and subsequent vacuum hot pressing method. To investigate phase development and surface morphology during the process, X-ray diffraction (XRD) and scanning electron microscopy (SEM) were carried out. It should be noted that an additional 16 at. % Mg must be added to the system to compensate for Mg loss during the melting process. This study evaluated the thermoelectric properties of the material in terms of Seebeck coefficient, electrical conductivity and thermal conductivity from the low to high temperature regime. The results demonstrated that substituting Zn at Mg sites increased electrical conductivity without significantly affecting the Seebeck coefficient. The maximal dimensionless figure of merit achieved was 0.30 for x = 0.01 at 855 K which is 30% greater than the intrinsic value. Electronic flow properties were also evaluated and discussed to explain the carrier transport mechanism involved in the thermoelectric properties of this alloy system.

• The Transactions of the Korean Institute of Power Electronics
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• v.27 no.1
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• pp.56-62
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• 2022

In this paper, the effect of pulse width modulation methods on thermal loadings and power losses of single-phase five-level NPC inverters for photovoltaic systems are analyzed. The pulse width modulation methods affect the power losses of the NPC inverters and thus lead to different thermal loadings of NPC inverters. To identify the reliability-critical power device with respect to thermal stress, the thermal loadings of I- and T-type NPC inverters are analyzed by applying the unipolar pulse modulation method. Then, the effect of the discontinuous pulse width modulation method on power losses and thermal loadings of power devices of I- and T-type NPC inverters are analyzed. Finally, the operation of NPC inverters applying the discontinuous pulse modulation method is confirmed by experiments. The results show that the discontinuous pulse modulation method is able to improve the reliability of NPC inverters by reducing thermal loadings of reliability-critical power devices and it is more effective for T-type NPC inverters than I-type NPC inverters.

• Clinical and Experimental Pediatrics
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• v.65 no.2
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• pp.73-80
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• 2022

A mercury sphygmomanometer (MS) has been the gold standard for pediatric blood pressure (BP) measurements, and diagnosing hypertension is critical. However, because of environmental issues, other alternatives are needed. Noninvasive BP measurement devices are largely divided into auscultatory and oscillometric types. The aneroid sphygmomanometer, the currently used auscultatory method, is inferior to MS in terms of limitations such as validation and regular calibration and difficult to apply to infants, in whom Korotkoff sounds are not audible. The oscillometric method uses an automatic device that eliminates errors caused by human observers and has the advantage of being easy to use; however, owing to its measurement accuracy issues, the development of an international validation protocol for children is important. The hybrid method, which combines the auscultatory and electronic methods, solves some of these problems by eliminating the observer bias of terminal digit preference while maintaining measurement accuracy; however, the auscultatory method remains limited. As the age-related characteristics of the pediatric group are heterogeneous, it is necessary to reconsider the appropriate BP measurement method suitable for this indication. In addition, the mobile application-based BP measurement market is growing rapidly with the development of smartphone applications. Although more research is still needed on their accuracy, many experts expect that mobile application-based BP measurement will effectively reduce medical costs due to increased ease of access and early BP management.

• The Journal of Korean Academic Society of Nursing Education
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• v.29 no.1
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• pp.72-85
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• 2023

Purpose: The aims of this study were to identify the psychosocial interventions for patients with alcohol use disorder and to assess the effects of those interventions. Methods: A systematic literature search was conducted using PubMed, the Cochrane Library, Embase, CINAHL, PsycINFO, KoreaMed, KMBASE, RISS, KISS, Science ON, and DBpia to identify studies reported in English or Korean from 2012 to 2021. Results: From the 4,051 studies extracted, 14 studies were selected for review. The majority of the psychosocial interventions were focused on cognitive therapy or cognitive-behavior therapy. Most of the studies reported that the interventions made positive effects on alcohol consumptions. In addition, the psychosocial interventions for patients with alcohol use disorder were effective on coping, support, alcohol avoidance behavior, and hostility bias. Most of the studies reporting positive effects of psychosocial intervention programs applied computers, mobile phones, or similar electronic devices. Conclusion: The findings of this systematic review suggest that the use of computers or mobile devices in psychosocial intervention programs will be effective. It can be said that this systematic review reflects the current trends involving the development of information and communication technology. This systematic review can provide basic data for establishing evidence and suggesting future directions for psychosocial interventions for patients with alcohol use disorder.

• ETRI Journal
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• v.45 no.3
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• pp.543-550
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• 2023

Electrostatic discharge (ESD) testing for human body model tests is an essential part of the reliability evaluation of electronic/electrical devices and components. However, global environmental concerns have called for the need to replace the mercury-wetted relay switches, which have been used in ESD testers. Therefore, herein, we propose an ESD tester using metal oxide semiconductor-controlled thyristor (MCT) devices with a significantly higher rising rate of anode current (di/dt) characteristics. These MCTs, which have a breakdown voltage beyond 3000 V, were developed through an in-house foundry. As a replacement for the existing mercury relays, the proposed ESD tester with the developed MCT satisfies all the requirements stipulated in the JS-001 standard for conditions at or below 2000 V. Moreover, unlike traditional relays, the proposed ESD tester does not generate resonance; therefore, no additional circuitry is required for resonant removal. To the best of our knowledge, the proposed ESD tester is the first study to meet the JS-001 specification by applying a new switch instead of an existing mercury-wetted relay.

• Journal of the Korea Society of Computer and Information
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• v.14 no.10
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• pp.167-174
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• 2009

We have recently studied the application of Information Technology to agricultural industry for competitive power. Because the big stockyards are far away from the house, we need a realtime monitering and control system to manage it efficiently. This paper presented design and implementation for a realtime monitering and controlling system that we can use to watch an movement of an electronic devices in the stockyards. Compared to other systems, we have more trust in our system by confirming an operation of devices through a realtime video streaming.

• Nuclear Engineering and Technology
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• v.56 no.2
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• pp.568-574
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• 2024

The development of radiation-tolerant radio-frequency (RF) systems can be a solution for applications in extreme radiation environments, such as nuclear power plant monitoring and space exploration. Among the crucial components within an RF system, the low noise amplifier (LNA) stands out due to its vulnerability to TID effects, mainly relying on transistors as its main devices. In this study, the TID effects in the LNA using standard 0.18 ㎛ complementary metal oxide semiconductors (CMOS) technology are estimated and analyzed. The results show that the LNA can withstand absorbed radiation up to 100 kGy. The S₂₁, S₁₁, noise figure (NF), stability (K), and linearity of the third input intercept point (IIP3) slightly shifted from the initial values of 0.8312 dB, 0.793 dB, 0.00381 dB, 1.34406, and 2.36066 dBm, respectively which are still comparable to the typical performances. Moreover, the standard 0.18 ㎛ technology has demonstrated its radiation tolerance, as it exhibits negligible performance degradation in the conventional LNA even when exposed to radiation levels up to 100 kGy. In this context, simulation approach offers a means to predict the TID effects and estimate the radiation exposure limit for electronic devices, particularly when transistors are used as the primary RF components.

• Journal of the Institute of Electronics and Information Engineers
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• v.52 no.5
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• pp.106-114
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• 2015

Wireless Body Area Network(WBAN) is a network standard around a human body which connects various medical sensor and devices It has to satisfy various demands such as data transmission rate, priority, and delay time. In this paper, considering a data priority and transmission delay time, is proposed to improve efficiency of WBAN service depending on congestion status of network. The proposed algorithm operates with adapted data removal probability according to data priority when the hub buffer is congested than before. And in the case of lower congestion within the hub buffer data is served considering data delay time. Through the comparison with other existing scheduling algorithms, it is confirmed that quality of WBAN service is improved due to lower data loss rate of medical data and less delay time in the proposed algorithm.

• Journal of the Institute of Electronics and Information Engineers
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• v.53 no.7
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• pp.11-16
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• 2016

Silicon carbide (SiC) has received significant attention over the past decade because of its high-voltage, high-frequency and high-thermal reliability in devices compared to silicon. Especially, a SiC Schottky barrier diode (SBD) is most often used in low-voltage switching and low on-resistance power applications. However, electric field crowding at the contact edge of SBDs induces early breakdown and limits their performance. To overcome this problem, several edge termination techniques have been proposed. This paper proposes an improvement in the breakdown voltage using a double-field-plate structure in SiC SBDs, and we design, simulate, fabricate, and characterize the proposed structure. The measurement results of the proposed structure, demonstrate that the breakdown voltage can be improved by 38% while maintaining its forward characteristics without any change in the size of the anode contact junction region.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.48 no.4
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• pp.43-50
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• 2011

Sensor networks are expected to play key roles in establishment of fundamental infrastructures, information collection, and devices control to provide services for ubiquitous society in the near future, where recent issues include energy efficient energy supply scheme in the sensor network based systems has been getting more attention. This paper formulates an energy supply problem that minimizes the total energy supplied to clustered sensor networks while maintaining the network lifetime. An energy supply scheme is suggested that determines the the amount of engergy supply to each cluster head based on the solution of the problem. Simulation results show that the proposed scheme achieves better energy efficiency compared with a simple scheme of maximum possible energy supply to each cluster head.