• Journal of the Korea Institute of Information and Communication Engineering
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• v.9 no.8
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• pp.1834-1839
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• 2005

Database security is essential to protect their data in most organization such as hospitals, central or local governments, banks which manage the private, sensitive and important data. Because the duty of the department recently became more various and complicated, the changes of security requirement are needed more frequently. Therefore, easily changeable, flexible security policy and efficient security management with preserving the integrity of security policy are very important. In this paper, we implemented a flexible database security system in the specimen and clinical information management system of leukemic research center using IRH(Improved Role Hierarchy). Data is protected by MAC and we propose a flexible access control and effective administration by using the IRH that is an improved role hierarchy of RBAC. If security policy is needed for changes, this system can do it easily by simply modifying the IRH with the decentralized administration. The modified security policy can be applied flexibly after alteration because the security level of the subject is not fixed but can be derived automatically from the IRH when user connects the system.

• Journal of Korean Physical Therapy Science
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• v.9 no.4
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• pp.7-14
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• 2002

The drug therapy for rheumatoid arthritis must be maintained constantly or for the whole life but is apt to induce the adverse effects in gastrointestinal or renal system. Therefor, newer methods are paid attention to reduce adverse effects. The thirty-two rat female separated into seven groups depending on the therapy or Freund's adjuvant applied: Normal group(n=8) not received anything, Positive control group(n=8) only received adjuvant, USC group(n=8) received continuous US, USP group(n=8) received pulsed US. The physical and radiological findings by thermal and non-thermal effects of ultrasound were evaluated in groups with continuous mode at 1 MHz, $0.5\;W/cm^2$ for 6 minutes and with pulsed mode (duty cycle 1:9) at 1 MHz, $0.5\;W/cm^2$ for 6 minutes. The result summarized followings. 1. Swelling of forepaw and hindpaw was significantly reduced in USP. 2. Arthritis indices in USP group were significantly reduced than those in PCG. 3. In naked eye and radiologic findings, swelling was significantly prevented in USP group but not in PCG. The change of swelling, arthritis index, gross feature in naked eye, radiologic finding were significantly improved in all groups except for USC group, taking care for using its continuous mode.

• Transactions of the Korean Society of Automotive Engineers
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• v.15 no.1
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• pp.193-200
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• 2007

Natural gas is one of the most promising alternatives to gasoline and diesel fuels because of its lower harmful emissions, including $CO_2$, and high thermal efficiency. In particular, natural gas is seen as an alternative fuel for heavy-duty Diesel Engines because of the lower resulting emissions of PM, $CO_2$ and $NO_x$. Almost all CNG vehicles use the PFI-type Engine. However, PFI-type CNG Engines have a lower brake horse power, because of reduced volumetric efficiency and lower burning speed. This is a result of gaseous charge and the time losses increase as compared with the DI-type. This study was conducted to investigate the effect of injection conditions (early injection mode, late injection mode) on the combustion phenomena and performances in the or CNG Engine. A DI Diesel Engine with the same specifications used in a previous study was modified to a DI CNG Engine, and injection pressure was constantly kept at 60bar by a two-stage pressure-reducing type regulator. In this study, excess air ratios were varied from 1.0 to the lean limit, at the load conditions 50% throttle open rate and 1700rpm. The combustion characteristics of the or CNG Engine - such as in-cylinder pressure, indicated thermal efficiency, cycle-by-cycle variation, combustion duration and emissions - were investigated. Through this method, it was possible to verify that the combustion duration, the lean limit and the emissions were improved by control of injection timing and the stratified mixture conditions. And combustion duration is affected by not only excess air ratio, injection timing and position of piston but gas flow condition.

• Transactions on Electrical and Electronic Materials
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• v.12 no.6
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• pp.262-266
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• 2011

A simulation study of a current-mode direct current (DC)-DC boost converter is presented in this paper. This converter, with a fully-integrated power module, is implemented by using bipolar complementary metal-oxide semiconductor (BiCMOS) technology. The current-sensing circuit has an op-amp to achieve high accuracy. With the sense metal-oxide semiconductor field-effect transistor (MOSFET) in the current sensor, the sensed inductor current with the internal ramp signal can be used for feedback control. In addition, BiCMOS technology is applied to the converter, for accurate current sensing and low power consumption. The DC-DC converter is designed with a standard 0.35 ${\mu}m$ BiCMOS process. The off-chip inductor-capacitor (LC) filter is operated with an inductance of 1 mH and a capacitance of 12.5 nF. Simulation results show the high performance of the current-sensing circuit and the validity of the BiCMOS converter. The output voltage is found to be 4.1 V with a ripple ratio of 1.5% at the duty ratio of 0.3. The sensing current is measured to be within 1 mA and follows to fit the order of the aspect ratio, between sensing and power FET.

• Structural Engineering and Mechanics
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• v.69 no.4
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• pp.407-416
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• 2019

This paper develops a wireless sensor for online fatigue crack detection and failure warning based on crack-induced nonlinear ultrasonic modulation. The wireless sensor consists of packaged piezoelectric (PZT) module, an excitation/sensing module, a data acquisition/processing module, a wireless communication module, and a power supply module. The packaged PZT and the excitation/sensing module generate ultrasonic waves on a structure and capture the response. Based on nonlinear ultrasonic modulation created by a crack, the data acquisition/processing module periodically performs fatigue crack diagnosis and provides failure warning if a component failure is imminent. The outcomes are transmitted to a base through the wireless communication module where two-levels duty cycling media access control (MAC) is implemented. The uniqueness of the paper lies in that 1) the proposed wireless sensor is developed specifically for online fatigue crack detection and failure warning, 2) failure warning as well as crack diagnosis are provided based on crack-induced nonlinear ultrasonic modulation, 3) event-driven operation of the sensor, considering rare extreme events such as earthquakes, is made possible with a power minimization strategy, and 4) the applicability of the wireless sensor to steel welded members is examined through field and laboratory tests. A fatigue crack on a steel welded specimen was successfully detected when the overall width of the crack was around $30{\mu}m$, and a failure warnings were provided when about 97.6% of the remaining useful fatigue lives were reached. Four wireless sensors were deployed on Yeongjong Grand Bridge in Souht Korea. The wireless sensor consumed 282.95 J for 3 weeks, and the processed results on the sensor were transmitted up to 20 m with over 90% success rate.

• Women's Health Nursing
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• v.25 no.3
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• pp.239-257
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• 2019

Purpose: To analyze the job of nursing unit managers working at women's hospital, using DACUM (developing a curriculum), DACUM is a method for analyzing job-focused competency. Methods: This study involved a descriptive survey. A DACUM workshop was held to define women's hospital nursing unit managers' role and identify their duties and tasks. For the workshop, a committee was formed consisting of 5 women's hospital nursing unit managers. Finally, after validation, the developed contents were made into a survey asking about nursing unit manager's duties and tasks. Results: Sixteen duties and 83 tasks were identified on the DACUM chart. The importance, difficulty, and frequency of the tasks were ranked in terms of A, B, and C, with A being the highest degree. Eight tasks received A's all in importance, difficulty, and frequency of performance. The 8 tasks were: 'taking over', 'taking care of seriously ill patients on handover', 'ward rounding', 'analyzing and resolving demands identified during handover and patient tour', 'reporting patient status during rounding', 'promoting breast-feeding', 'uterine contraction, and training for breast-feeding'. The duty with the biggest determinant coefficient (DC) was 'patients complaint management' (DC=7.09). Based on tasks, the one with the biggest DC was 'solving patient and patient guardian's complaints' (DC=7.53), followed by 'making infection control guidelines' (DC=7.5). Conclusion: When expanding the nursing staff of the hospital, women's hospitals nursing unit managers also need to use administrative functions as intermediaries to focus on the operation management of the entire hospital rather than direct nursing to suit their role.

• Journal of Power Electronics
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• v.19 no.1
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• pp.190-200
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• 2019

The flyback converter, which can be regarded as a nonlinear time-varying system, has complex dynamics and nonlinear behaviors. These phenomena can affect the stability of the converter. To simplify the modeling process and retain the information of the output capacitor branch, a special sampled-data model of a peak current-mode (PCM) controlled flyback converter is established in this paper. Based on this, its dynamic behaviors are analyzed, which provides guidance for designing the circuit parameters of the converter. With the critical stability boundary equation derived by a Jacobian matrix, the stable operation range with a varied output capacitor, proportional coefficient of error the amplifier, input voltage, reference voltage and slope of the compensation ramp of a PCM controlled flyback converter are investigated in detail. Research results show that the duty ratio should be less than 0.5 for a PCM controlled flyback converter without ramp compensation to operate in a stable state. The stability regions in the parameter space between the output capacitor and the proportional coefficient of the error amplifier are enlarged by increasing the input voltage or by decreasing the reference voltage. Furthermore, the ramp compensation also can extend to the stable region. Finally, time-domain simulations and experimental results are presented to verify the theoretical analysis results.

• Journal of the Korean Society of School Health
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• v.34 no.1
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• pp.76-86
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• 2021

Purpose: This study was conducted to describe the experience of school health teachers in regard to the COVID-19 pandemic in South Korea. Methods: We conducted a qualitative study using content analysis. Ten school health teachers were recruited from 6 elementary schools, 2 middle schools and 2 high schools in Seoul, using purposive sampling. They participated in semi-structured in-depth interviews in person or using an online communication system from January to February, 2021. Interviews were transcribed verbatim and analysed using qualitative content analysis. Results: Three main categories and nine generic categories emerged from the analysis. Firstly, it was discovered that school health teachers had psychological and physical stress to cope with COVID-19 due to the 1) fear of the unexpected infectious disease, 2) burden of having to deal with it alone, 3) breakdown of personal life and physical exhaustion and 4) heavy duty as a health teacher caused by the lack of an organic cooperation system with institutions related to school infectious diseases. Secondly, school health teachers had an increased sense of empowerment in regard to infectious disease management as a result of 1) feeling rewarded and appreciated and 2) gaining confidence and trust in infectious disease management. Finally, school health teachers experienced the urgent need for an effective response strategy for infection control because of the 1) confusion over infectious disease response due to lack of practical manuals applicable to the field as well as training, 2) disappointing response system without an expert response team dedicated to managing infectious diseases in schools, and 3) growing awareness of the need for change. Conclusion: It is expected that school health teachers' experience of COVID-19 will be used as important data for building effective and advanced school infectious disease response systems.

• Journal of the Korea Society of Computer and Information
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• v.27 no.2
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• pp.107-114
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• 2022

Delegation is a powerful mechanism that allocates access rights to users to provide flexible and dynamic access control decisions. It is also particularly useful in a distributed environment. Among the representative delegation models, the RBDM0 and RDM2000 models are role delegation as the user to user delegation. However, In RBAC, the concept of inheritance of the role class is not well harmonized with the management rules of the actual corporate organization. In this paper, we propose an Adding Attributes on Permission-Based Delegation Model (ABDM) that guarantees the permanence of delegated permissions. It does not violate the separation of duty and security principle of least privilege. ABDM based on RBAC model, supports both the role to role and user to user delegation with an attribute. whenever the delegator wants the permission can be withdrawn, and A delegator can give permission to a delegatee.

• Journal of Home Health Care Nursing
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• v.30 no.1
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• pp.15-25
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• 2023

Purpose: This study describes the associations between shift work factors, workplace violence bystander types, and the missed nursing care of hospital nurses. Methods: A cross-sectional survey was conducted among hospital nurses using structured questionnaires related to shift work factors, workplace violence bystander types, and missed nursing care. The study participants were 199 nurses caring for adult patients and working in two tertiary hospitals. Results: The missed nursing care of the participants showed a statistically significant positive correlation with the facilitating bystander (r=.40, p<.001) and abdicating bystander (r=.28, p<.001) among the workplace violence bystander types. However, rest time during duty showed a significant negative correlation (r=-.16, p=.026). A regression model with control variables (department and clinical career), shift work factors, and workplace violence bystander types explained approximately 25% of missed nursing care of the study participants. Further, the facilitating bystander type influenced the missed nursing care of hospital nurses. Conclusion: As a result of examining the associations between shift work factors, workplace violence bystander types, and missed nursing care of hospital nurses, it was confirmed that missed nursing care was influenced by the facilitating bystander type. It is necessary to improve the nursing culture within the department so that nurses do not behave as negative bystanders to workplace violence.