• Journal of Korean Academy of Nursing Administration
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• v.7 no.2
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• pp.265-284
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• 2001

The case management has been applied to improve the quality of care and the cost-effectiveness in the most health care institutions. In a way of case management, the critical pathway(CP) has been executed in many acute care settings, focused on the diagnoses with high cost, high volume, and high risk. This study was conducted to develop a case management program using CP as an intervention of patients with lumbar spinal stenosis for the surgery of posterolateral fusion, and to find out the effects of the critical pathway on the quality of nursing care, patient satisfaction as an outcome of care, length of stay and medical charge, and nurses' job satisfaction. At the same time, patients' functional states were checked with the Oswestry Low Back Pain Index, to show that the CP would not decrease the patients' function compared to the control group. The subjects were 25 control patients with a usual operation of lumbar fusion and 25 experimental patients with CP. They were all female, aged $50s{\sim}70s$, admitted in the Orthopedic surgery ward of a university hospital. Also nurses on the floor using CP were asked to respond to measurement tool of job satisfaction before and after the application of CP, and compared with other nurses on the different wards. Data were analyzed with t-test for continuous variables and chi-square for non-parametric variables in addition to the reliability test of the measurement tools. The results of this study were as followings: 1. Patients' functional states The differences in Oswestry scores of the experimental and control groups assessed at preoperation and at discharge were not statistically significant. The change in scores of the experimental group measured at preoperation and at discharge was larger than that of the control group, however the difference was not statistically significant. The results indicate that the CP did not decrease the patients' functional status. 2. The quality of nursing care The total of quality of nursing care given to the experimental group was better than that of the control group(P=.000). In addition, the experimental group showed better scores of quality of every item of care than the control group(P=.000 -.004). 3. Patient satisfaction Patients of the experimental group were not more satisfied with general care than the control group. But they were more satisfied with discharge care of 'explanation about medication, body posture, and brace application' and 'explanation about the adjustment of daily living and exercise during recovery'(P= .047, P=.028). 4. Nurses' job satisfaction Nurses working with the CP showed more job satisfaction than before the CP introduction(P=.048). But the control group of nurses on a different floor showed no change in job satisfaction at the same period of time. 5. Length of stay and medical charge The mean length of stay of the experimental group was shorter than that of the control group without statistical significance. The charge of medication and treatment of the experimental group were smaller than that of the control group(P=.011, P=.000). The results of the study support that the case management using critical pathway enables to improve the quality of care and job satisfaction, to reduce the medical charge, and consequently to increase satisfaction with care. However, the case management should be instituted focusing on the quality improvement of nursing and the client satisfaction, not just for the purpose of cost-effectiveness of health care facilities.

• Journal of the Korean Chemical Society
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• v.50 no.3
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• pp.243-246
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• 2006

The LiCoO2 thin films were prepared on the Pt/Ti/SiO2/Si substrate by spin coating using citrate sol. The citrate sol was spin-coated on substrate and dried at 380oC for 15 min. to evaporate the solvents and remove the organic materials. The as-deposited films were annealed at 750oC for 10 min. in air for crystallization. The X-ray diffraction patterns for the film have been indexed hexagonal system with space group R3m. The active area of LiCoO2 films for electrochemical test was about 11cm2. A Li foil and 1M LiClO4 in propylene carbonate(PC) and ethylene carbonate(EC) (1:1)were used as an anode and an electrolyte, respectively. The galvanostatic charge-discharge test was carried out at constant current density ranging from 5 A/cm2 in the voltage window between 4.2 and 3.0 V. The first discharge capacity of the film is 0.35Ah/cm2-m. The cycling behavior of the LiCoO2 film is also reported.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.17 no.10
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• pp.883-890
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• 2005

In this study, 2 pure hydrocarbon refrigerants of R1270 (Propylene) and R290 (Propane) and 3 binary mixtures composed of R1270, R29O and R152a were tested in a refrigerating bench tester with a scroll compressor in an attempt to substitute R502 used in most of the low temperature applications. The test bench provided 3\sim3.5$ kW capacity and water and water/glycol mixture were employed as the secondary heat transfer fluids. All tests were conducted under the same external conditions resulting in the average saturation temperatures of -28 and $45^{\circ}C$ in the evaporator and condenser, respectively. Test results showed that all refrigerants tested had $9.6\sim18.7\%$ higher capacity and $17.1\sim27.3\%$ higher COP than R502. The compressor discharge temperature of R1270 was similar to that of R502 while those of all other refrigerants were $23.7\sim27.9\%$ lower than that of R502. For all alternative refrigerants, the amount of charge was reduced up to $60\%$ as compared to R502. Overall, these alternative refrigerants offer better system performance and reliability than R502 and can be used as long term substitutes for R502 due to their excellent environmental properties.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.18 no.10
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• pp.761-767
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• 2006

In this study, performance of 2 pure hydrocarbons R290 and R1270 was measured in an attempt to substitute R22 under 3 different temperature conditions. They were tested in a refrigerating bench tester with a hermetic rotary compressor. The test bench provided about 3.5 kW capacity and water and water/glycol mixture were employed as the secondary heat transfer fluids. All tests were conducted under the same external conditions resulting in the average saturation temperatures of $7/45^{\circ}C$ and $-7/41^{\circ}C$ and $-21/28^{\circ}C$ in the evaporator and condenser, respectively. Test results show that the coefficient of performance (COP) of these refrigerants is up to 11.54% higher than that of R22 in all temperature conditions. Compressor discharge temperatures were reduced by $14{\sim}31^{\circ}C$ with these fluids. There was no problem with mineral oil since the mixtures were mainly composed of hydrocarbons. The amount of charge was reduced up to 58% as compared to R22. Overall, these fluids provide good performance with reasonable energy savings without any environmental problem and thus can be used as long term alternatives for residential air-conditioning and heat pumping application.

• Proceedings of the SAREK Conference
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• 2006.06a
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• pp.58-63
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• 2006

In this study, performance of 2 pure hydrocarbons and 3 mixtures was measured in an attempt to substitute R22 under 3 different temperature conditions. The mixtures were composed of R1270(propylene), R290(propane) and R152a. They were tested in a refrigerating bench tester with a hermetic rotary compressor The test bench provided about 3.5 kW capacity and water and water/glycol mixture were employed as the secondary heat transfer fluids. All tests were conducted under the same external conditions resulting in the average saturation temperatures of $7^{\circ}C/45^{\circ}C$ and $-7^{\circ}C/41^{\circ}C$ and $-21^{\circ}C/28^{\circ}C$ in the evaporator and condenser, respectively. Test results show that the coefficient of performance (COP) of these refrigerants is up to 11.54% higher than that of R22 in all temperature conditions. Compressor discharge temperatures were reduced by $14{\sim}31^{\circ}C$ with these fluids. There was no problem with mineral oil since the mixtures were mainly composed of hydrocarbons. The amount of charge was reduced up to 58% as compared to R22. Overall, these fluids provide good performance with reasonable energy savings without any environmental problem and thus can be used as long term alternatives for residential air-conditioning and heat pumping application.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.18 no.4
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• pp.312-319
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• 2006

In this study, performance of 2 pure hydrocarbons and 7 mixtures was measured in an attempt to substitute HCFC22 used in air-conditioners and heat pumps. The mixtures were composed of R1270 (propylene), R290 (propane), HFC152a, and RE170 (Dimethyl ether, DME). The pure and mixed refrigerants tested have GWPs of $3{\sim}58$ as compared to that of $CO_2$ and the mixtures are all near-azeotropic showing the gliding temperature difference (GTD) of less than $0.6^{\circ}C$. Thermodynamic cycle analysis was carried out to determine the optimum compositions and actual tests were performed in a laboratory heat pump test bench at the evaporation and condensation temperatures of 7.5 and $45.1^{\circ}C$ respectively. Test results show that the coefficient of performance (COP) of these mixtures is up to 5.7% higher than that of HCFC22. While propane showed 11.5% reduction in capacity, most of the fluids tested had the similar capacity to that of HCFC22. Compressor discharge temperatures were reduced by $11{\sim}17^{\circ}C$ with these fluids. There was no problem with mineral oil since the mixtures were mainly composed of hydrocarbons. The amount of charge was reduced up to 55% as compared to HCFC22. Overall, these fluids provide good performance with reasonable energy savings without any environmental problem and thus can be used as long term alternatives for. residential air-conditioning and heat pumping application.

• Journal of Electrochemical Science and Technology
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• v.13 no.4
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• pp.472-478
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• 2022

Solar energy harvesting is practiced by various nations for the purpose of energy security and environment preservation in order to reduce overdependence on oil. Converting solar energy into electrical energy through Photovoltaic (PV) module can take place either in on-grid or off-grid applications. In recent time Lithium battery is exhibiting its presence in on-grid applications but its role in off-grid application is rarely discussed in the literature. The preliminary capacity and Peukert's study indicated that the battery quality is good and can be subjected for life cycle test. The capacity of the battery was 10.82 Ah at 1 A discharge current and the slope of 1.0117 in the Peukert's study indicated the reaction is very fast and independent on rate of discharge. In this study Lithium Iron Phosphate battery (LFP) after initial characterization was subjected to life cycle test which is specific to solar off-grid application as defined in IEC standard. The battery has delivered just 6 endurance units at room temperature before its capacity reached 75% of rated value. The low life of LFP battery in off-grid application is discussed based on State of Charge (SOC) operating window. The battery was operated both in high and low SOC's in off-grid application and both are detrimental to life of lithium battery. High SOC operation resulted in cell-to-cell variation and low SOC operation resulted in lithium plating on negative electrode. It is suggested that to make it more suitable for off-grid applications the battery by default has to be overdesigned by nearly 40% of its rated capacity.

• Journal of the Korean Electrochemical Society
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• v.4 no.4
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• pp.152-159
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• 2001

Electric vehicle performance is very dependent on traction batteries. For developing the electric vehicles with high performance and good reliability, the traction batteries have to be managed to get maximum performance under various operating conditions. The enhancement of the battery performance can be accomplished by implementing battery management system (BMS) that plays important roles of optimizing the control mechanism of charge and discharge of the batteries as well as monitoring battery status. In this study the battery management system has been developed for maximizing the use of Ni/MH batteries in electric vehicle. This system provides several tasks: the control of charging and discharging, overcharge and over-discharge protection, the calculation and display of state of charge, safety and thermal management. The BMS was installed in and tested using the DEV5-5 electric vehicle developed by Daewoo Motor Co. and Institute for Advanced Engineering in Korea. The 18 modules of Panasonic Ni/MH battery, 12 V-95 Ah, were used in the DEV5-5. The high accuracy within the range of $3\%$ and the good reliability were shown in the test results. The BMS can also improve the performance and cycle life of Ni/MH battery pack as well as the reliability and safety of the electric vehicles (EV).

• Journal of the Korean Electrochemical Society
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• v.11 no.4
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• pp.289-296
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• 2008

Electrochemical studies were performed by a half-cell test for the nickel hydroxide (cathode) and hydrogen storage alloy(anode) electrodes for the sealed Ni-MH batteries applicable to industrial use. The electrodes were fabricated and checked a charge efficiency and an internal pressure of the battery during charge-discharge cycling. In order to reduce the internal pressure of the sealed Ni-MH battery, cyclic voltammetry (CV) were performed on the electrodes of nickel hydroxide(cathode) and hydrogen storage alloy(anode), respectively. The results of the test showed clearly the oxidation/reduction and oxygen evolution reaction in a nickel hydroxide electrode and the hydrogenation behavior of a hydrogen storage electrode. The sealed Ni-MH battery of 130Ah was fabricated by using nickel hydroxide of a high over-voltage for an oxygen gas evolution and hydrogen storage alloy of a good performance for activation The battery showed a good characteristics such as a high charge efficiency of 98% at 1 C charge current, a low level internal pressure of 4 atm on a continuous over-charging and a large preservation capacity of 95% at 400 cycle.

• JSTS:Journal of Semiconductor Technology and Science
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• v.15 no.4
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• pp.445-453
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• 2015

A fully integrated cost-effective and low-power single chip Lithium-Ion (Li-Ion) battery protection IC (BPIC) for portable devices is presented. The control unit of the battery protection system and the MOSFET switches are integrated in a single package to protect the battery from over-charge, over-discharge, and over-current. The proposed BPIC enters into low-power standby mode when the battery becomes over-discharged. A new auto release function (ARF) is adopted to release the BPIC from standby mode and safely return it to normal operation mode. A new delay shorten mode (DSM) is also proposed to reduce the test time without increasing pin counts. The BPIC implemented in a $0.18-{\mu}m$ CMOS process occupies an area of $750{\mu}m{\times}610{\mu}m$. With DSM enabled, the measured test time is dramatically reduced from 56.82 s to 0.15 s. The BPIC chip consumes $3{\mu}A$ under normal operating conditions and $0.45{\mu}A$ under standby mode.