• 제어로봇시스템학회:학술대회논문집
• /
• 제어로봇시스템학회 1997년도 한국자동제어학술회의논문집; 한국전력공사 서울연수원; 17-18 Oct. 1997
• /
• pp.1726-1729
• /
• 1997

In general, the solvability of linear robust output regulation problem are not preserved under time-sampling. Thus, it is found that the digital regulator implemented by itme-sampling of anlog output regulator designed based on the continuous-time linear system model is nothing but a 1st order approximation with respect to time-sampling. By the way, one can design an improved sampled-data regulator with respect to sampling time by utilizing the intrinsic structure of the system. In this paper, we study the system structures which it is possible to design an improved sampled-data regulator with respect to sampling time.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2001년도 하계학술대회 논문집 D
• /
• pp.2531-2533
• /
• 2001

This paper describes a low noise and high efficiency analog-digital switching mixed mode battery charger for production facilities of Li-Ion batteries. The requirements for battery chargers for production facilities are very strict. The accuracy of output voltage and output current should be below 0.1% with very low ripple current. Therefore analog type linear regulators are widely used for battery charger in spite of their inefficiency and bulkiness. We combined linear regulator as a voltage source with digital switching converter as a dependent current source. Low current ripple and high accuracy are obtained by linear regulator while high efficiency is achieved by digital switching converter. Experimental results show that proposed method has 0.1% ripple and 90% efficiency at an output current of 1A for a battery voltage of 4V.

• The Journal of Asian Finance, Economics and Business
• /
• 제8권11호
• /
• pp.121-131
• /
• 2021

This study aims at investigating the effects of digital accounting implementation on audit performance of tax auditors in Thailand through audit competency and audit report as the consequence. In addition, it examines the effects of audit learning, digital culture, and stakeholder expectation on digital accounting implementation. The key informants were Thailand's tax auditors. The data was collected using a questionnaire that was distributed to 349 tax auditors throughout Thailand. The response rate was 20.53%. The Ordinary Least Squares (OLS) is applied to test the research relationships. The results of this study show that digital accounting implementation has an important effect on its consequence, namely audit competency, audit report, and audit performance. Similarly, audit competency and audit report affect audit performance. Testing the antecedents of the research relationships, namely audit learning, digital culture, and stakeholder expectation, the result reveals that only digital culture affects digital accounting implementation. Accordingly, digital accounting implementation plays a vital role to enhance audit competency, audit report, and ultimately lead to attaining audit performance. Furthermore, the results are beneficial for the auditing practitioners and regulators, allowing them to draw on these results to develop training programs to enhance professional audit efficiency.

• 대한전기학회논문지
• /
• 제40권9호
• /
• pp.937-944
• /
• 1991

In digital controller design, the delays in the controller should be taken into consideration when the computation time of the processor is not negligibale compared with sampling time. Recently, Mita has proposed a digital optimal servosystem taking account of the delays in the controller. In this paper, robust stability and diturbance rejection properties of this optimal servosystej are analyzed in the frequency-domain. The well-known asymptotic properties of the optimal regulators with respect to the weighting matrices of the cost functions are successfully utilized to show that the influence of the delays in the controller are drastic for certain choice of the cost function Illustrative numerical examples are presented.

• Journal of Power Electronics
• /
• 제10권4호
• /
• pp.342-350
• /
• 2010

Randomizing the switching frequency (RSF) to reduce the electromagnetic interference (EMI) of switching power converters is a well-known technique that has been previously discussed. The randomized pulse position (RPP) technique, in which the switching frequency is kept fixed while the pulse position (the delay from the starting of the switching cycle to the turn-on instant within the cycle) is randomized, has been previously addressed in the literature for the same purpose. This paper presents a double-hybrid technique (DHB) for EMI reduction in dc-dc switching regulators. The proposed technique employed both the RSF and the RPP techniques. To effectively spread the conducted-noise frequency spectrum and at the same time attain a satisfactory output voltage quality, two parameters (switching frequency and pulse position) were randomized, and a third parameter (the duty ratio) was controlled by a digital compensator. Implementation was achieved using field programmable gate array (FPGA) technology, which is increasingly being adopted in industrial electronic applications. To evaluate the contribution of the proposed DHB technique, investigations were carried out for each basic PWM, RPP, RSF, and DHB technique. Then a comparison was made of the performances achieved. The experimentally investigated features include the effect of each technique on the common-mode, differential-mode, and total conducted-noise characteristics, and their influence on the converter’s output ripple voltage.

• Nuclear Engineering and Technology
• /
• 제52권5호
• /
• pp.995-1001
• /
• 2020

With the development of digital instrumentation and control (I&C) devices, cyber security at nuclear power plants (NPPs) has become a hot issue. The Stuxnet, which destroyed Iran's uranium enrichment facility in 2010, suggests that NPPs could even lead to an accident involving the release of radioactive materials cyber-attacks. However, cyber security research on industrial control systems (ICSs) and supervisory control and data acquisition (SCADA) systems is relatively inadequate compared to information technology (IT) and further it is difficult to study cyber-attack taxonomy for NPPs considering the characteristics of ICSs. The advanced research of cyber-attack taxonomy does not reflect the architectural and inherent characteristics of NPPs and lacks a systematic countermeasure strategy. Therefore, it is necessary to more systematically check the consistency of operators and regulators related to cyber security, as in regulatory guide 5.71 (RG.5.71) and regulatory standard 015 (RS.015). For this reason, this paper attempts to suggest a template for cyber-attack taxonomy based on the characteristics of NPPs and exemplifies a specific cyber-attack case in the template. In addition, this paper proposes a systematic countermeasure strategy by matching the countermeasure with critical digital assets (CDAs). The cyber-attack cases investigated using the proposed cyber-attack taxonomy can be used as data for evaluation and validation of cyber security conformance for digital devices to be applied, and as effective prevention and mitigation for cyber-attacks of NPPs.

• 전기전자학회논문지
• /
• 제27권3호
• /
• pp.333-339
• /
• 2023

세계적으로 웨어러블 디바이스의 시장이 확장하고 있으며, 이를 위한 효율적인 PMIC의 수요 또한 늘어나고 있다. 웨어러블 디바이스용 PMIC 특성상 높은 에너지 효율과 작은 면적이 필요하다. 프로세스 기술의 발전으로 저전력 설계가 가능하지만, 기존의 아날로그 LDO 레귤레이터는 전원 전압이 낮아짐에 따라 설계의 어려움이 있다. 본 논문에서는 이중 루프 디지털 LDO용 coarse-fine ADC를 제안한다, ADC의 설계는 55 nm CMOS 공정으로 진행하였고 34.78 dB와 5.39 bits의 SNR과 ENOB를 갖는다.

• 한국IT서비스학회지
• /
• 제21권6호
• /
• pp.73-89
• /
• 2022

After COVID-19, the percentage of digital consumption has soared. Meanwhile, as the online platform market grows in size and digital commerce is activated, controversy over the "dark pattern" that induces consumers to do unintended things online continues. Dark patterns are deceptive design patterns that cause consumer rights and financial damage and can result in damaging fair market competition. As a result, the need to regulate dark patterns is raised not only by overseas regulators but also in Korea, and there are growing calls for strengthening consumer protection against dark patterns, with amendments to related laws being proposed by the National Assembly. On the other hand, there is no agreed definition of dark pattern from a normative point of view, and there is a concern that even legitimate advertising marketing activities of companies may be regulated, so a review of dark pattern regulatory measures is required. In this study, dark patterns were reviewed from a normative point of view and appropriate regulatory measures were analyzed. In particular, the problem of the dark pattern can be applied in a way that the market regulates and controls itself in consideration of the characteristics of the online platform. This study reviewed the possibility of self-regulation for dart patterns and proposed the role of each subject.

• 한국통신학회논문지
• /
• 제35권4B호
• /
• pp.620-629
• /
• 2010

지상파 아날로그 텔레비전 방송의 종료시기가 확정됨에 따라 텔레비전 방송의 디지털화에 많은 관심이 집중되고 있어 상대적으로 라디오의 디지털화는 논의의 우선순위에서 밀려나 있지만, 라디오 방송의 디지털 전환 추진도 더 이상 미루기 어려운 시점이라 할 수 있다. 디지털라디오 방송은 아날로그 라디오 방송의 고유한 입지를 고수 하면서 청취자에게 CD 수준의 음질과 다양한 데이터서비스를 제공하여 수용자의 편익과 복지 향상에 기여할 것으로 기대된다. 디지털라디오 방송이 시장에 도입되어 활성화되기 위해서는 수용자들의 디지털라디오에 대한 이용 의향이 요구된다. 그러므로 디지털라디오 방송이 수용자들에 의해 채택되고, 이를 바탕으로 확산이 일어나는데 영향을 미치는 요인들에 대한 면밀한 고찰이 필요한 시점이다. 본 논문에서는 디지털라디오 방송에 대한 산업적 관심과 원활한 수요창출을 유도할 수 있는 방안을 모색하기 위하여, 설문조사를 통해 디지털라디오 방송의 이용에 영향을 미치는 요인들을 분석하였다. 이를 통해 향후 디지털라디오 방송이 시작될 경우 수용자의 이해를 바탕으로 디지털라디오 방송시장의 활성화 가능성과 디지털라디오 방송이 제공해야 할 기술적 특성과 서비스의 방향성을 제시하고자 하였다.

• Journal of Advanced Marine Engineering and Technology
• /
• 제40권1호
• /
• pp.39-44
• /
• 2016

선박 및 해양플랜트용 자동전압조정기(AVR)는 발전기의 출력전압을 실시간 검출하여 기준 전압으로 조정하는 장치로서 기존에는 아날로그 타입의 자동전압조정기가 주로 사용되었지만 목표값에 대한 응답성과 신속성의 개선이 요구됨으로써 디지털 방식의 전압조정기로 대체되는 추세이다. 본 논문에서는 부하변동이 심하고 운전 환경이 열악한 해양플랜트 발전기용 자동전압조정기의 특성에 적합한 디지털 자동전압조정기 시스템을 새롭게 구성하였으며 부하변동 및 임의의 출력전압 변동 실험을 통해 안정성과 속응성을 비교하여 우수성을 입증하였다. 또한, 실시간으로 발전기의 출력 전압과 여자기의 계자전류를 감시하고 자동전압조정기의 게인 값을 편리하게 조정할 수 있는 통합제어시스템을 개발하였다.