• Korean Chemical Engineering Research
• /
• v.47 no.1
• /
• pp.72-78
• /
• 2009

For the electro-discharge machining of an electro-conductive anisotropic composite, an unsteady state formulation was established and solved by Galerkin's finite element method. The distribution of temperature on work piece, the shape of the crater and the material removal rate were obtained in terms of the process parameters. The $12{\times}12$ irregular mesh that was chosen as the optimum in the previous analysis was used for computational accuracy and efficiency. A material having the physical properties of alumina/titanium carbide composite was selected and an electricity with power of 51.4 V and current of 7 A was applied, assuming the removal efficiency of 10 % and the thermal anisotropic factors of 2 and 3. As the spark was initiated the workpiece immediately started to melt and the heat affected zone was formed. The moving boundary of the crater was also identified with time. When the radial and axial conductivities were increased separately, the temperature distribution and the shape of the crater were shifted in the radial and axial directions, respectively. The material removal rate was found to be higher when the conductivity was increased in the radial direction rather than in the axial direction.

• Journal of Preventive Medicine and Public Health
• /
• v.14 no.1
• /
• pp.59-64
• /
• 1981

Korean Medical Insurance Cooperation executed the physical checkup intended for all the members of public officials, school personnel in private schools, and the insured as a national-wide event in 1980. This is the result of a part of Taegu district and its contiguous country this hospital took charge of. Physical checkup method was divided into the first health examination and tile second health examination. The second health examination was executed for those who needed reexamination according to the result of the first health examination. After that, we passed judgement on the result finally. The total number of the first health examination was 10,779; 4,606 in public officials, 2,327 in police constables, 3,976 in school personnel in private schools. The classification of physical checkup is as follows; A group: normal groups B group: those who do not require immediate medical care but require preventive measures or who are doubtful of disease or who had undetermined diagnosis (attention) C group: those who require immediate medical care but who are able to be on duty (simple recuperation) D group: those who require immediate medical treatment and recuperation (suspension from office and recuperation) Total B group to the in the first health examination was 4.73%, that of total C,D groups 2.21%. That of total C,D groups to the total in the first health examination by occupation was 2.30% in public officials, 2.19% in police constables, 2.04% in school personnel. Consequently there was no different among occupations. Total C,D groups of hypertension to the total in the first health examination was 1.68% and hypertension was 76.05% to all disease. These rates mentioned to above were higher than any other rate in disease. Subsequently, being low, the rate of diabetes was 15.54%. From the view point of age, the higher rate appeared in men and women over 35 years old of B group and over 45 years old of C,D groups in three occupations in comparison with other ages and the older men were, the higher men who took a disease were.

• International Journal of Advanced Culture Technology
• /
• v.7 no.4
• /
• pp.63-68
• /
• 2019

Recently, the United States and China have declared a 25% retaliatory tariff for the partner country products of 50 billion dollar scale. "Trade war" is getting full swing. Such conflicts between economic powers may spread to Japan like the domino phenomenon following the EU (European Union) and become bigger in the global trade war. As a result, Korea has an economic system with a high degree of external dependence, and there is an expert's analysis that it will become the largest victim of the global trade war. If the WTO Dispute Settlement Authority approves this US 301 retaliation measure in the same way as the past case (US-EU hormone-treated beef imports), the United States will not import any Chinese imported products Chinese products) can be imposed. If the US launches a special 301 or super 301, which is stronger than the regular 301, then China is very likely to enforce US retaliation against it, and the trade war between the two countries could become a reality. This phenomenon is likely to have a negative impact on Korean companies. In particular, Korea, which is highly reliant on intermediate goods exports to China, is expected to suffer a great deal of damage. Therefore, Korea needs flexible response at home and abroad, it is necessary to enhance the autonomy of companies and protect export industries. Adjusting corporate tax rate as well as domestic industry height will be one way. The long-term (21 months) trade war between the United States and China has resulted in economic uncertainty. The resulting damage must be compensated. It is necessary to prepare the compensation through the economic council between countries. In the future, the punitive damage compensation system should be introduced.

• Safety and Health at Work
• /
• v.13 no.2
• /
• pp.148-154
• /
• 2022

Background: Bus driving is a mentally demanding activity that requires prolonged attention to ensure safety. The aim of the study was to assess mental fatigue caused by driving a public bus and to find a profile of workers at higher risk. Methods: We evaluated changes of critical flicker fusion (CFF) (index of central arousal) and heart rate variability (HRV) (index of autonomic balance) in a 6-hour driving shift on a real route, in 31 professional bus drivers, and we tested the influence of personal factors such as sleep quality, BMI, and age. Paired t-test was used to test differences of CFF and HRV between both initial and final phase of driving, while multiple linear regression tested the influence of personal variables on the indexes of mental fatigue. Results: Results showed that CFF significantly decreased after 6 hours of bus driving (41.91 Hz, sd 3.31 vs. 41.15 Hz, sd 3.15; p = 0.041), and heart rate significantly decreased in the final phase of driving, with respect to the initial phase (85 vs. 78 bpm, p = 0.027). Increasing age (beta = -0.729, p = 0.022), risk of obstructive sleep apnea syndrome (beta = -0.530, p = 0.04), and diurnal sleepiness (beta = -0.406, p = 0.017) showed a significant effect on influencing mental fatigue. Conclusion: Elderly drivers at higher risk of sleep disorders are more prone to mental fatigue, when exposed to driving activity. Monitoring indexes of central arousal and autonomic balance, coupled with the use of structured questionnaires can represent a useful strategy to detect profile of workers at higher risk of mental fatigue in such duty.

• The Korean Society of Law and Medicine
• /
• v.18 no.1
• /
• pp.143-169
• /
• 2017

The Act on Special Cases Concerning the Punishment, etc. of Child Abuse Crimes intends to encourage reporting and punishment of child abuse by using the concept of 'crime' in child abuse cases. Article 10 of the Act imposes duty to report child abuse on a number of different professions, including medical professionals. Currently, more than 80% of child abuse cases occur among family members and the detection rate of child abuse is as low as 0.5% in Korea. On the other hand, medical professionals can identify child abuse relatively clearly with specific medical opinions. Therefore, it is necessary that medical professions are informed of this duty and does not bear disincentive from reporting. This paper makes policy suggestions in this regard. First, it is necessary that medical students and medical professionals receive regular education about the obligation to report child abuse. Education should include details of the reporting duty, as well as the fact that there is legal obligation to report even if the child abuse is "suspicious", not certain. Second, it is imperative to establish and implement protective programs for medical professionals who report child abuse. The current law provides a rough framework for protection of people who report child abuse, but it is necessary to produce detailed guidelines that are applicable in the context of medical setting. Education for medical students and medical professionals should include the contents of these guidelines, so that they do not hesitate reporting because they fear the aftermath of reporting. Third, it is highly recommended that physicians use the national Baby/Infant Health Checkup Program as an opportunity to detect child abuse. In Korea, the Baby/Infant Health Checkup Program provides physicians to periodically monitor health condition of all babies and children until the age of 71 months. In order to utilize this program for early detection of child abuse, it is imperative that the bBaby/Infant Health Checkup Program is modified to involve child abuse experts and medical professionals who participate in the program are educated about child abuse.

• Journal of the Institute of Electronics Engineers of Korea SC
• /
• v.46 no.2
• /
• pp.72-77
• /
• 2009

In this paper, a 3.2Gb/s clock and data recovery (CDR) circuit for a high-speed serial data communication without the reference clock is described This CDR circuit consists of 5 parts as Phase and frequency detector(PD and FD), multi-phase Voltage Controlled-Oscillator(VCO), Charge-pumps (CP) and external Loop-Filter(KF). It is adapted the PD and FD, which incorporates a half-rate bang-bang type oversampling PD and a half-rate FD that can improve pull-in range. The VCO consists of four fully differential delay cells with rail-to-rail current bias scheme that can increase the tuning range and tuning linearity. Each delay cell has output buffers as a full-swing generator and a duty-cycle mismatch compensation. This materialized CDR can achieve wide pull-in range without an extra reference clock and it can be also reduced chip area and power consumption effectively because there is no additional Phase Locked- Loop(PLL) for generating reference clock. The CDR circuit was designed for fabrication using 0.18um 1P6M CMOS process and total chip area excepted LF is $1{\times}1mm^2$. The pk-pk jitter of recovered clock is 26ps at 3.2Gb/s input data rate and total power consumes 63mW from 1.8V supply voltage according to simulation results. According to test result, the pk-pk jitter of recovered clock is 55ps at the same input data-rate and the reliable range of input data-rate is about from 2.4Gb/s to 3.4Gb/s.

• Journal of Information Processing Systems
• /
• v.2 no.1
• /
• pp.39-43
• /
• 2006

In this paper, we proposed TASL-MAC, a medium-access control (MAC) protocol for wireless sensor networks. In wireless sensor networks, sensor nodes are usually deployed in a special environment, are assigned with long-term work, and are supported by a limited battery. As such, reducing the energy consumption becomes the primary concern with regard to wireless sensor networks. At the same time, reducing the latency in multi-hop data transmission is also very important. In the existing research, sensor nodes are expected to be switched to the sleep mode in order to reduce energy consumption. However, the existing proposals tended to assign the sensors with a fixed Sleep/Listening schedule, which causes unnecessary idle listening problems and conspicuous transmission latency due to the diversity of the traffic-load in the network. TASL-MAC is designed to dynamically adjust the duty listening time based on traffic load. This protocol enables the node with a proper data transfer rate to satisfy the application's requirements. Meanwhile, it can lead to much greater power efficiency by prolonging the nodes' sleeping time when the traffic. We evaluate our implementation of TASL-MAC in NS-2. The evaluation result indicates that our proposal could explicitly reduce packet delivery latency, and that it could also significantly prolong the lifetime of the entire network when traffic is low.

• Journal of Korean Clinical Nursing Research
• /
• v.14 no.2
• /
• pp.59-70
• /
• 2008

Purpose: Purposes of this study were to promote understanding on mutually informed consent by comparing and analyzing the perception and experience of informed consent among physicians, nurses, and patients. Method: Participants in the study were 145 physicians, 300 nurses, and 178 patients from eight hospitals in Busan. To examine their understanding and experience with informed consent, all participants responded to a questionnaire. The collected data were analyzed using SPSS/PC 12.0 program. Results: On the necessity of informed consent, the affirmative percentages were 95.9% for physicians, 99.0% for nurses and 84.8% for patients. As to the most important reason for informed consent 47.6% of the physicians and 64.3% of the nurses answered 'because it is an occupational and ethical duty', while 46.6% of the patients answered 'because it is protection for physicians'. Regarding the legal decision maker for informed consent, 33.1% of the physicians, 27% of the nurses, and 42.1% of the patients answered that the legal decision-making right belonged to the 'patient'. The agreement rate on the necessity of providing a comprehensive explanation about informed consent was 89.0% for physicians, 98.3% for nurses, and 96.1% for patients. Conclusion: Most physicians, nurses, and even patients have inaccurate perceptions and inappropriate experience with informed consent.

• The Journal of Asian Finance, Economics and Business
• /
• v.7 no.12
• /
• pp.515-521
• /
• 2020

Work motivation is critical for ensuring sustainability of any business firm. Motivated personnel essentially helps an organization achieve its organizational goal and objective. Hence, it has become an essential duty for business managers and management committees to identify the motivating factors that would strongly affect their employees. The purpose of the current research is to identify which are the factors that motivate service employees most at their workplace in Bangladesh. The study has used survey questionnaires to collect data from service employees. Convenience sampling is used for data collection. A total of 240 questionnaires were distributed and 183 completed questionnaires were returned (response rate: 77%). The study used purposeful motivating factors, which are ranked (from 1 to 10) by the service employees according to the significance of the factors. Mean value is applied to determine the most crucial motivating factor, where the factor with lowest mean value is considered as the highest significant motivating factor. Results reveal that job certainty, career growth and advancement opportunity, and quality working environment have been the most crucial and influential motivating factors for the service employees. The study adequately underlines the necessity of motivational factors and provides some guidelines to keep employees motivated.

• ETRI Journal
• /
• v.40 no.2
• /
• pp.167-179
• /
• 2018

This paper proposes an IEEE 802.15.4m compliant TV white-space orthogonal frequency-division multiplexing (TVWS)-(OFDM) radio frequency (RF) transceiver that can be adopted in advanced metering infrastructures, universal remote controllers, smart factories, consumer electronics, and other areas. The proposed TVWS-OFDM RF transceiver consists of a receiver, a transmitter, a 25% duty-cycle local oscillator generator, and a delta-sigma fractional-N phase-locked loop. In the TV band from 470 MHz to 698 MHz, the highly linear RF transmitter protects the occupied TV signals, and the high-Q filtering RF receiver is tolerable to in-band interferers as strong as -20 dBm at a 3-MHz offset. The proposed TVWS-OFDM RF transceiver is fabricated using a $0.13-{\mu}m$ CMOS process, and consumes 47 mA in the Tx mode and 35 mA in the Rx mode. The fabricated chip shows a Tx average power of 0 dBm with an error-vector-magnitude of < 3%, and a sensitivity level of -103 dBm with a packet-error-rate of < 3%. Using the implemented TVWS-OFDM modules, a public demonstration of electricity metering was successfully carried out.