• Journal of Korean Tunnelling and Underground Space Association
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• v.23 no.6
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• pp.517-534
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• 2021

Hydrogen fuel is emerging as an new energy source to replace fossil fuels in that it can solve environmental pollution problems and reduce energy imbalance and cost. Since hydrogen is eco-friendly but highly explosive, there is a high concern about fire and explosion accidents of hydrogen fueled vehicles. In particular, in semi-enclosed spaces such as tunnels, the risk is predicted to increase. Therefore, this study was conducted on the applicability of the equivalent TNT model and the numerical analysis method to evaluate the hydrogen explosion pressure in the tunnel. In comparison and review of the explosion pressure of 6 equivalent TNT models and Weyandt's experimental results, the Henrych equation was found to be the closest with a deviation of 13.6%. As a result of examining the effect of hydrogen tank capacity (52, 72, 156 L) and tunnel cross-section (40.5, 54, 72, 95 m²) on the explosion pressure using numerical analysis, the explosion pressure wave in the tunnel initially it propagates in a hemispherical shape as in open space. Furthermore, when it passes the certain distance it is transformed a plane wave and propagates at a very gradual decay rate. The Henrych equation agrees well with the numerical analysis results in the section where the explosion pressure is rapidly decreasing, but it is significantly underestimated after the explosion pressure wave is transformed into a plane wave. In case of same hydrogen tank capacity, an explosion pressure decreases as the tunnel cross-sectional area increases, and in case of the same cross-sectional area, the explosion pressure increases by about 2.5 times if the hydrogen tank capacity increases from 52 L to 156 L. As a result of the evaluation of the limiting distance affecting the human body, when a 52 L hydrogen tank explodes, the limiting distance to death was estimated to be about 3 m, and the limiting distance to serious injury was estimated to be 28.5~35.8 m.

• The Korean Journal of Nuclear Medicine Technology
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• v.18 no.2
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• pp.22-27
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• 2014

Purpose There is the recent PET/CT scan in tendency that use low dose to reduce patient's exposure along with development of equipments. We diminished $^{18}F$-FDG dose of patient to reduce patient's exposure after setting up GE Discovery 690 PET/CT scanner (GE Healthcare, Milwaukee, USA) establishment at this hospital in 2011. Accordingly, We evaluate acquisition time per proper bed by change of infusion dose to maintain quality of image of PET/CT scanner. Materials and Methods We inserted Air, Teflon, hot cylinder in NEMA NU2-1994 phantom and maintained radioactivity concentration based on the ratio 4:1 of hot cylinder and back ground activity and increased hot cylinder's concentration to 3, 4.3, 5.5, 6.7 MBq/kg, after acquisition image as increase acquisition time per bed to 30 seconds, 1 minute, 1 minute 30 seconds, 2 minute, 2 minutes 30 seconds, 3 minutes, 3 minutes 30 seconds, 4 minutes, 4 minutes 30 seconds, 5 minutes, 5 minutes 30 seconds, 10 minutes, 20 minutes, and 30 minutes, ROI was set up on hot cylinder and back radioactivity region. We computated standard deviation of Signal to Noise Ratio (SNR) and BKG (Background), compared with hot cylinder's concentration and change by acquisition time per bed, after measured Standard Uptake Value maximum ($SUV_{max}$). Also, we compared each standard deviation of $SUV_{max}$, SNR, BKG following in change of inspection waiting time (15minutes and 1 hour) by using 4.3 MBq phantom. Results The radioactive concentration per unit mass was increased to 3, 4.3, 5.5, 6.7 MBqs. And when we increased time/bed of each concentration from 1 minute 30 seconds to 30 minutes, we found that the $SUV_{max}$ of hot cylinder acquisition time per bed changed seriously according to each radioactive concentration in up to 18.3 to at least 7.3 from 30 seconds to 2 minutes. On the other side, that displayed changelessly at least 5.6 in up to 8 from 2 minutes 30 seconds to 30 minutes. SNR by radioactive change per unit mass was fixed to up to 0.49 in at least 0.41 in 3 MBqs and accroding as acquisition time per bed increased, rose to up to 0.59, 0.54 in each at least 0.23, 0.39 in 4.3 MBqs and in 5.5 MBqs. It was high to up to 0.59 from 30 seconds in radioactivity concentration 6.7 MBqs, but kept fixed from 0.43 to 0.53. Standard deviation of BKG (Background) was low from 0.38 to 0.06 in 3 MBqs and from 2 minutes 30 seconds after, low from 0.38 to 0 in 4.3 MBqs and 5.5 MBqs from 1 minute 30 seconds after, low from 0.33 to 0.05 in 6.7 MBqs at all section from 30 seconds to 30 minutes. In result that was changed the inspection waiting time to 15 minutes and 1 hour by 4.3 MBq phantoms, $SUV_{max}$ represented each other fixed values from 2 minutes 30 seconds of acquisition time per bed and SNR shown similar values from 1 minute 30 seconds. Conclusion As shown in the above, when we increased radioactive concentration per unit mass by 3, 4.3, 5.5, 6.7 MBqs, the values of $SUV_{max}$ and SNR was kept changelessly each other more than 2 minutes 30 seconds of acquisition time per bed. In the same way, in the change of inspection waiting time (15 minutes and 1 hour), we could find that the values of $SUV_{max}$ and SNR was kept changelessly each other more than 2 minutes 30 seconds of acquisition time per bed. In the result of this NEMA NU2-1994 phantom experiment, we found that the minimum acquisition time per bed was 2 minutes 30 seconds for evaluating values of fixed $SUV_{max}$ and SNR even in change of inserting radioactive concentration. However, this acquisition time can be different according to features and qualities of equipment.

• Journal of Korea Water Resources Association
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• v.53 no.1
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• pp.15-27
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• 2020

Streamflow discharge as a fundamental riverine quantity plays a crucial role in water resources management, thereby requiring accurate in-situ measurement. Recent advances in instrumentations for the streamflow discharge measurement has complemented or substituted classical devices and methods. Among various potential methods, surface current meter using microwave has increasingly begun to be applied not only for flood but also normal flow discharge measurement, remotely and safely enabling practitioners to measure flow velocity postulating indirect contact. With minimized field preparedness, this method facilitated and eased flood discharge measurement in the difficult in-situ conditions such as extreme flood in active ways emitting 24.125 GHz microwave without relying on natural lights. In South Korea, a rectangular shaped instrument named with Microwave Water Surface Current Meter (MWSCM) has been developed and commercially released around 2010, in which domestic agencies charging on streamflow observation shed lights on this approach regarding it as a potential substitute. Considering this brand-new device highlighted for efficient flow measurement, however, there has been few noticeable efforts in systematic and comprehensive evaluation of its performance in various measurement and riverine conditions that lead to lack in imminent and widely spreading usages in practices. This study attempted to evaluate the MWSCM in terms of instrumen's monitoring configuration particularly regarding tilt and yaw angle. In the middle of pointing the measurement spot in a given cross-section, the observation campaign inevitably poses accuracy issues related with different tilt and yaw angles of the instrument, which can be a conventionally major source of errors for this type of instrument. Focusing on the perspective of instrument configuration, the instrument was tested in a controlled outdoor river channel located in KICT River Experiment Center with a fixed flow condition of around 1 m/s flow speed with steady flow supply, 6 m of channel width, and less than 1 m of shallow flow depth, where the detailed velocity measurements with SonTek micro-ADV was used for validation. As results, less than 15 degree in tilting angle generated much higher deviation, and higher yawing angle proportionally increased coefficient of variance. Yaw angles affected accuracy in terms of measurement area.

• The Korean Journal of Emergency Medical Services
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• v.15 no.1
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• pp.47-63
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• 2011

Purpose : This research is to examine the work and job satisfaction of paramedics in the emergency room of university hospitals. This research is done to provide basic data needed for establishing work realms of paramedics in hospitals and to enhance their degree of satisfaction. Methods : Research questionnaire survey was conducted on 141 paramedics working in the emergency room of 32 university hospitals from August 24, 2010 to September 30, 2010 through direct visits and telephone interviews or email to explain the purpose of this research and assurance of confidentiality of responses on the questionnaires. As the tool for the degree of job satisfaction, 'The Index of Work Satisfaction' developed by Slavitt, et al(1978) and revised and supplemented by Soon-shim Kim and Hye-ran Kwon(2002) was used. The collected data were analyzed by evaluating frequency, percentage, mean, standard deviation, t-test and ANOVA, Cronbach's $\alpha$ by using SPSS WIN 18.0 program. Results : 1. Investigating the work and role of paramedics in the emergency room of university hospitals, electrocardiogram(EKG) was found to be highest with $\alpha$ was widely used with the rate of patient evaluation and test area. In the medical treatment for patients area, cardiopulmonary resuscitation(CPR) with 95%(134 persons) and ventilation assistance through ambu bagging(BVM) with 95%(134 persons) were found to be high. $\alpha$ were performed. In the role within the hospital and other areas, a member of CPR team in the hospital accounted for 78%(110 persons). 2. In the measurements of the job satisfaction of paramedics working at university hospitals, the total mean score was 2.91. The mean score in each question area indicated: section on job 3.48, autonomy 3.05, interaction 3.01, organizational demand 2.85, working conditions 2.67, salaries 2.40. This result obviously demonstrates the work of paramedics itself was most satisfied but the salaries were most dissatisfied. 3. In the measurements of the job satisfaction of paramedics working at university hospitals, job satisfaction based on the general characteristics showed significant difference in age (F=6.547, p=.002), gender (F=4.436, p=.000) marital status (F=-3.270, p= .001), religion (F=2.041, p= .043), motive for application (F=3.603, p= .015), and salary (F=6.658, p= .000). 대학병원 응급실 내 1급 응급구조사의 업무와 직무만족도 The Journal of the Korean Society of Emergency Medical Technology Vol. 15 (1) 63 4. In the measurements of the job satisfaction of paramedics working at university hospitals, job satisfaction based on the working environmental characteristics showed significant difference in total number of paramedics (F=3.779, p= .012), form of employment (F=5.601, p= .001), existence or non-existence of intention to change jobs (F=-4.037, p= .000). Conclusion : The work of paramedics in the emergency room of university hospitals consists of lots of treatment processes after specialized diagnosis and performance of professionally subdivided works. However, current legislation does not reflect such circumstances to which paramedics are exposed; thus, it should be considered for further revision and modification. The degree of job satisfaction of paramedics in the emergency room of university hospitals was high but low in salaries and working conditions were the weak points. The measures to enhance their degree of job satisfaction should be taken though improvement of labor conditions such as consideration of the rate of increase in salaries, compensation for overtime work, providing rest areas, improvement of current employment system, and conversion of temporary employees into regular employees.

• Journal of the Korea institute for structural maintenance and inspection
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• v.15 no.6
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• pp.135-146
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• 2011

Steel structures have been generally painted to prevent corrosion damage. However, the painted film is deteriorated with increase in service life, and then corrosion damage resulting in cross sectional area occurs on steel surface. As a result, the buckling strength of steel structures can be decreased due to the corrosion damages. The evaluation method of the axial buckling strength of columns about a variety of section shapes and supporting conditions have been presented, but evaluation method of buckling strength about irregular nonprismatic columns is not established. In this study, the axial buckling strength of corroded steels was evaluated based on the buckling test results of corroded steel specimens that were cut off at a temporary steel structure. The corroded specimens were picked up total 10 specimens according to various slenderness ratio from the web of a temporary structure's main beam. The length of specimens is 200, 300, 400, 500 and 600mm respectively. The rust productions were removed by the chemical treatment. Then, the surface geometry was measured at intervals of $1{\times}1mm$ by using the optical 3D digitizing system, and the residual thickness of the specimens was calculated. The axial buckling test was performed on 10 corroded specimens and 12 non-corroded specimens under the fixed-fixed support condition. From the test results, the effect of corrosion damages on axial buckling load was investigated. Regardless of corrosion damage degree, the axial buckling strength of corroded specimens and non-corroded specimens was evaluated identically by using minimum average residual thickness or average residual thickness to minus its standard deviation. Reasonable measuring intervals of residual thickness was proposed by using the results to apply for practical works.

• Journal of Korean Academy of Nursing Administration
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• v.6 no.3
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• pp.389-404
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• 2000

This study was designed to determine the cost and measurement of nursing care hours for hospice patients hostpitalized in one university hospital. 314 inpatients in the hospice unit 11 nursing manpower were enrolled. Study was taken place in C University Hospital from 8th to 28th, Nov, 1999. Researcher and investigator did pilot study for selecting compatible hospice patient classification indicators. After modifying patient classification indicators and nursing care details for general ward, approved of content validity by specialist. Using hospice patient classification indicators and per 5 min continuing observation method, researcher and investigator recorded direct nursing care hours, indirect nursing care hours, and personnel time on hospice nursing care hours, and personnel time on hospice nursing care activities sheet. All of the patients were classified into Class I(mildly ill), Class II (moderately ill), Class III (acutely ill), and Class IV (critically ill) by patient classification system (PCS) which had been carefully developed to be suitable for the Korean hospice ward. And then the elements of the nursing care cost was investigated. Based on the data from an accounting section (Riccolo, 1988), nursing care hours per patient per day in each class and nursing care cost per patient per hour were multiplied. And then the mean of the nursing care cost per patient per day in each class was calculated. Using SAS, The number of patients in class and nursing activities in duty for nursing care hours were calculated the percent, the mean, the standard deviation respectively. According to the ANOVA and the $Scheff{\'{e}$ test, direct nursing care hours per patient per day for the each class were analyzed. The results of this study were summarized as follows : 1. Distribution of patient class : class IN(33.5%) was the largest class the rest were class II(26.1%) class III(22.6%), class I(17.8%). Nursing care requirements of the inpatients in hospice ward were greater than that of the inpatients in general ward. 2. Direct nursing care activities : Measurement ${\cdot}$ observation 41.7%, medication 16.6%, exercise ${\cdot}$ safety 12.5%, education ${\cdot}$ communication 7.2% etc. The mean hours of direct nursing care per patient per day per duty were needed ; 69.3 min for day duty, 64.7 min for evening duty, 88.2 min for night duty, 38.7 min for shift duty. The mean hours of direct nursing care of night duty was longer than that of the other duty. Direct nursing care hours per patient per day in each class were needed ; 3.1 hrs for class I, 3.9 hrs for class II, 4.7 hrs for class III, and 5.2 hrs for class IV. The mean hours of direct nursing care per patient per day without the PCS was 4.1 hours. The mean hours of direct nursing care per patient per day in class was increased significantly according to increasing nursing care requirements of the inpatients(F=49.04, p=.0001). The each class was significantly different(p<0.05). The mean hours of direct nursing care of several direct nursing care activities in each class were increased according to increasing nursing care requirements of the inpatients(p<0.05) ; class III and class IV for medication and education ${\cdot}$ communication, class I, class III and class IV for measurement ${\cdot}$ observation, class I, class II and class IV for elimination ${\cdot}$ irrigation, all of class for exercise ${\cdot}$ safety. 3. Indirect nursing care activities and personnel time : Recognization 24.2%, house keeping activity 22.7%, charting 17.2%, personnel time 11.8% etc. The mean hours of indirect nursing care and personnel time per nursing manpower was 4.7 hrs. The mean hours of indirect nursing care and personnel time per duty were 294.8 min for day duty, 212.3 min for evening duty, 387.9 min for night duty, 143.3 min for shift duty. The mean of indirect nursing care hours and personnel time of night duty was longer than that of the other duty. 4. The mean hours of indirect nursing care and personnel time per patient per day was 2.5 hrs. 5. The mean hours of nursing care per patient per day in each class were class I 5.6 hrs, class II 6.4 hrs, class III 7.2 hrs, class IV 7.7 hrs. 6. The elements of the nursing care cost were composed of 2,212 won for direct nursing care cost, 267 won for direct material cost and 307 won for indirect cost. Sum of the elements of the nursing care cost was 2,786 won. 7. The mean cost of the nursing care per patient per day in each class were 15,601.6 won for class I, 17,830.4 won for class II, 20,259.2 won for class III, 21,452.2 won for class IV. As above, using modified hospice patient classification indicators and nursing care activity details, many critical ill patients were hospitalized in the hospice unit and it reflected that the more nursing care requirements of the patients, the more direct nursing care hours. Emotional ${\cdot}$ spiritual care, pain ${\cdot}$ symptom control, terminal care, education ${\cdot}$ communication, narcotics management and delivery, attending funeral ceremony, the major nursing care activities, were also the independent hospice service. But it is not compensated by the present medical insurance system. Exercise ${\cdot}$ safety, elimination ${\cdot}$ irrigation needed more nursing care hours as equal to that of intensive care units. The present nursing management fee in the medical insurance system compensated only a part of nursing car service in hospice unit, which rewarded lower cost that that of nursing care.