• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.21 no.6
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• pp.367-372
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• 2009

The performance of a $CO_2$ heat pump water heater was measured with a variation of operating conditions such as refrigerant charge amount, outdoor temperature, compressor frequency, EEV opening, and water mass flow rate. The optimum refrigerant charge amount of the $CO_2$ system was 1800 g. At water mass flow rates of 75, 85, and 95 kg/h, the water heating temperatures were 74, 67, and $62^{\circ}C$ and COPs were 2.6, 2.8, and 3.0, respectively. Besides, the compressor frequency and water mass flow rate were adjusted to maintain the water heating temperature at $60^{\circ}C$ with the decrease of outdoor temperature. As the outdoor temperature decreased by $5^{\circ}C$, the compressor frequency increased beyond 60 Hz and the water mass flow rate decreased by 16.7%.

• Proceedings of the SAREK Conference
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• 2008.11a
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• pp.310-315
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• 2008

In this study, experimental study on the heating performance of a $CO_2$ heat pump water heater with a variation of operating conditions such as refrigerant charge amount, outdoor temperature, compressor frequency, EEV opening and water mass flow rate. Based on the test results, the optimum charge amount was 1800 g. At the water mass flow rates of 75, 85, 95 kg/hr, the water heating temperature was 62, 67, $74^{\circ}C$ and COP was 2.6, 2.8, 3.0, respectively. Besides, the water mass flow rate and compressor frequency were varied to maintain above the water heating temperature of $60^{\circ}C$ with the decrease of outdoor temperature. So, The compressor frequency increased beyond 65 Hz and the water mass flow rate was 45 kg/hr at the outdoor temperature of $-13^{\circ}C$, 65 kg/hr at $-8^{\circ}C$, 75 kg/hr at $-3^{\circ}C$ and 85 kg/hr at 2, $7^{\circ}C$. As the outdoor temperature decreased, the heating COP decreased by 2.5-39.8%.

• Transactions of the Korean Society of Mechanical Engineers
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• v.13 no.4
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• pp.780-788
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• 1989

An experimental study has been performed to investigate the process from nonequilibrium state to equilibrium state in redeveloping turbulent boundary layer beyond separation-reattachment using pitot tube and hot-wire anemometer. The model sued in the experiment has the form of a backward facing step which is assembled by a two-dimensional 4:1 half elipse and a plate. Measurements are carried out up to a distance of about 50 step height downstream of the step, where the reattachment observed at about x/h=6.5. The profiles of the shape factor H the Clauser parameter G and the coefficient of friction $C^{f}$ exhibited the characteristics similar to those of the equilibrium turbulent boundary layer from x/h=25, and the profiles of the trubulent quantities did from x/h=35. However, the wake region of the boundary layer does not seem to recover the equilibrium turbulent boundary layer even at x/h=50. By considering the distributions of the intermittency factor it has been noted that the turbulence structure changes gradually from a mixing layer to a turbulent boundary layer along downstream direction after reattachment. This becomes clearer as we analyse the one-dimensional energy spectra and the dissipation energy spectra which are measured and caculated at various downstream positions after the backward facing step.p.

• Journal of Preventive Medicine and Public Health
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• v.52 no.5
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• pp.323-332
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• 2019

Objectives: The aim of this study was to describe general practitioners (GPs)' opinions and practices of preventive care and patients' opinions, attitudes, and behaviors towards prevention. Methods: The data stemmed from a cross-sectional national survey on prevention conducted in Switzerland from 2015 to 2016. In total, 170 randomly drawn GPs and 1154 of their patients participated. The GPs answered an online questionnaire and the patients answered a questionnaire administrated by fieldworkers present at their practices. Results: Both patients and GPs agreed that delivering preventive care is the dedicated role of a GP. It appeared that beyond classical topics of prevention such as cardiovascular risk factors, other prevention areas (e.g., cannabis consumption, immunization, occupational risks) were scarcely covered by GPs and reported as little-known by patients. In addition, GPs seemed to use a selective approach to prevention, responding to the clinical context, rather than a systematic approach to health promotion. The results also highlight possibilities to improve prevention in family medicine through options such as more supportive tools and public advertising, more time and more delegated tasks and, finally, a more recognized role. Conclusions: Despite an unfavorable context of prevention within the healthcare system, preventive care in family medicine is reasonably good in Switzerland. However, some limitations appear regarding the topics and the circumstances of preventive care delivery. A global effort is needed to implement necessary changes, and the responsibility should be broadened to other stakeholders.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.12 no.7
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• pp.1218-1226
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• 2008

With the development of semiconductor integrated technology and with the increasing use of multimedia functions in computer, more functions have been implemented as hardware. Nowadays, most microprocessors beyond 32 bits generally implement an integer multiplier as hardware. However, as for a divider, only specific microprocessor implements traditional SRT algorithm as hardware due to complexity of implementation and slow speed. This paper suggested an algorithm that uses a multiplier, 'w bit $\times$ w bit = 2w bit', to process $\frac{N}{D}$ integer division. That is, the reciprocal number D is first calculated, and then multiply dividend N to process integer division. In this paper, when the divisor D is '$D=0.d{\times}2^L$, 0.5 < 0.d < 1.0', approximate value of ' $\frac{1}{D}$', '$1.g{\times}2^{-L}$', which satisfies ' $0.d{\times}1.g=1+e$, $e<2^{-w}$', is defined as over reciprocal number and then an algorithm for over reciprocal number is suggested. This algorithm multiplies over reciprocal number '$01.g{\times}2^{-L}$' by dividend N to process $\frac{N}{D}$ integer division. The algorithm suggested in this paper doesn't require additional revision, because it can calculate correct reciprocal number. In addition, this algorithm uses only multiplier, so additional hardware for division is not required to implement microprocessor. Also, it shows faster speed than the conventional SRT algorithm and performs operation by word unit, accordingly it is more suitable to make compiler than the existing division algorithm. In conclusion, results from this study could be used widely for implementation SOC(System on Chip) and etc. which has been restricted to microprocessor and size of the hardware.

• Culinary science and hospitality research
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• v.21 no.6
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• pp.242-254
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• 2015

Barley is a main food source, along with rice, in our dietary life that is easy to buy and process. It is required to develop a beverage base and barley syrup for desserts in order to raise utilization of barley beyond its present use in Sikhye (sweet fermented rice drink) and Jocheong (grain syrup) production. In pursuit of the goal to increase the usability of barley as an ingredient of processed food, this study examined the optimal preparation conditions of barley mash for barley syrup. In addition, the study prepared a barley syrup using saccharified barley liquid, analyzed quality characteristics, and conducted a sensory evaluation. Saccharified barley liquid(barley mash) was prepared with ratios of adding malt of unhulled barley germinated as 0 g(CON), 10 g(BM10), 20 g(BM20), and 30 g(BM30). The results of measuring pH under the varied conditions of saccharification temperatures from $50^{\circ}C$, $60^{\circ}C$, and $70^{\circ}C$, as well as time from 1 to 8 hours, treveal that the optimum condition for malt saccharification is $60^{\circ}C$ for 5 hours. By adding oligosaccharides and lemon juice to the saccharified barley liquid at the different ratios of added malt, this study measured quality characteristics(color value, viscosity, pH, sweetness) of barley syrup warmed up for 1 hour. As the result of measuring color in the barley syrup prepared by saccharified barley liquid, higher levels of added malt saw L-value decreased while a-value and b-value both increased. BMs30 showed the highest viscosity of $1,202.67{\pm}3.06$. As for pH, BMs30 was the highest at pH $3.57{\pm}0.02$. The result of the sensory evaluation of barley syrup showed the superior sensory characteristics of BMs20 in terms of color, flavor, sweetness, viscosity and overall quality.

• Nuclear Engineering and Technology
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• v.55 no.3
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• pp.1061-1070
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• 2023

Over the last few years, lead-free inorganic metal perovskites have gained impressive ground in empowering satellites in space exploration owing to their material stability and performance evolution under extreme space environments. The present work has examined the versatility of eight such perovskites as space radiation shielding materials by computing their photon, charged particles and neutron interaction parameters. Photon interaction parameters were calculated for a wide energy range using PAGEX software. The ranges of heavy charged particles (H, He, C, N, O, Ne, Mg, Si and Fe ions) in these perovskites were estimated using SRIM software in the energy range 1 keV-10 GeV, and that of electrons was computed using ESTAR NIST software in the energy range 0.01 MeV-1 GeV. Further, the macroscopic fast neutron removal cross-sections were also calculated to estimate the neutron shielding efficiencies. The examined shielding parameters of the perovskites varied depending on the radiation type and energy. Among the selected perovskites, Cs₂TiI₆ and Ba₂AgIO₆ displayed superior photon attenuation properties. A 3.5 cm thick Ba₂AgIO₆-based shield could reduce the incident radiation intensity to half its initial value, a thickness even lesser than that of Pb-glass. Besides, CsSnBr₃ and La_0.8Ca_0.2Ni_0.5Ti_0.5O₃ displayed the highest and lowest range values, respectively, for all heavy charged particles. Ba₂AgIO₆ showed electron stopping power (on par with Kovar) better than that of other examined materials. Interestingly, La_0.8Ca_0.2Ni_0.5Ti_0.5O₃ demonstrated neutron removal cross-section values greater than that of standard neutron shielding materials - aluminium and polyethylene. On the whole, the present study not only demonstrates the employment prospects of eco-friendly perovskites for shielding space radiations but also suggests future prospects for research in this direction.

• Journal of Preventive Medicine and Public Health
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• v.29 no.1 s.52
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• pp.113-131
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• 1996

This study was carried out to evaluate the relations among workers' general characteristics, work-related behaviors and health related behaviors in a steel industry with 1,134 workers in Pohang. The results were as follows; 1. The mean age of workers was 50 years old and working duration was 15 years and over. Most of them were married(94.5%) and had studied beyond high school (53.0%). They performed three shift work and most of them(63.0%) had experienced industial accidents. The frequency of noise and dust exposure was defined by a minimum of 6 hours per day, and workers complained about noise exposure(62.9%) and dust(55.6%). There were current smokers(67.7%), current drinkers(74.3%) and current exercising workers(32.3%) in the industry. The number of cigarette consumption in current drinkers was significantly high $(13.6{\pm}8.4\;pieces/day)$ and the alcohol consumption in current smokers was significantly high$(104.5{\pm}113.5\;g/wk)$. And the number of cigarette consumption of exercisers was significantly low and the alcohol consumption of exercisers was higher than non-exercisers. 3. The ratio of current smokers on frequent noise in exposed workers versus non-exposed workers was not significantly high but the current drinkers in frequent noise and dust exposed workers was significantly higher than non-exposed. 4. The normal levels of SGOT workers in non-smokers were significantly higher than in current smokers, and the normal levels of LFT (SGOT, SGPT, $\gamma-GTP$ workers in nondrinkers were significantly high. The normal levels of SBP and DBP workers in current smokers were not significantly high but were significantly high in non-drinkers. 5. The ratio of current smokers in voters unsatisfied with their job and working condition was higher than non-smokers, but the ratio of current drinkers in workers satisfied with their job and working condition were higher. 6. The significant factors for SGOT and $\gamma-GTP$ were age, the drinking amount and BMI. But the only significant factor for r-GTP was BMI. The significant factors for DBP were age, the alcohol consumption and BMI. And the significant factors for SBP were age, BMI.

• The Korean Journal of Physiology
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• v.16 no.1
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• pp.13-23
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• 1982

Effects of external pH and potassium concentrations on the electrical and mechanical properties were investigated on rabbit papillary muscle. Papillary muscles were perfused in horizontal chamber with Tris Tyrode solutions and action potential along with isometric tension was recorded simultaneously. Potassium concentrations were varied between 1 and 12 mM at low(6.9), normal(7.4) and high (7.9) external pH. The following results were obtained: 1) On rasing the potassium concentration from 1 to 12 mM resting membrane potentials decreased from $-88.8{\pm}2.8$ to $-66.4{\pm}1.2\;mV$ at normal pH and the amplitude of action potential decreased from $115.1{\pm}0.7$ to $97.5{\pm}2.8\;mV$. On lowering the potassium concentration, membrane hyperpolarized and at 1 mM potassium concentration resting potentials were $-107{\pm}2.2\;mV$. Duration of action potential especially $APD_{60}{\sim}APD_{90}$ increased($APD_{90}$: $214{\pm}15.8\;ms$ at 1 mM $K^+$ to $287{\pm}18.1\;ms$ at 12 mM $K^+$). 2) During acidosis membranes hyperpolarized by more than 20 mV within 1 min. and then slow recovery was observed during the following 10 min. During alkalosis membranes depolarized about 10 mV, which were maintained until washing with normal Tyrode solutions. 3) On lowering the external pH(7.9-6.5), duration of action potential increased progressively and it was most prominent at pH 6.5 and $K^+$ 1mM. 4) Magnitude of developed tension was $0.6{\pm}0.14\;g/mm^2$ at normal pH and potassium concentration (stimulus frequency : 60/min). Relative isometric tension to normal value increased along the increment of stimulus frequency($44.2{\pm}4.2%$ at 6/min to $271{\pm}86.7%$ at 180/min). Force-frequency relations were altered quantitatively during the perfusion with different external pH solutions. 5) Developed tension did not show marked variation within the range of $2{\sim}8\;mM$ potassium concentrations. Positive inotropism was observed at less than 2 mM $K^+$ and negative inotropism beyond 12 mM $K^+$ concentrations. From the above results we concluded that the effects of potassium ion concentration on electrical and mechanical properties of rabbit papillary muscle are related to the changes in surface negative charge due to acid base disturbances.

• 한국정보디스플레이학회:학술대회논문집
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• 2005.07b
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• pp.1203-1206
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• 2005

Electron temperature and plasma density in coplanar alternating-current plasma display panels (AC-PDP's) have been experimentally investigated in accordance with discharge time by a micro-probe in this experiment. The resolution of a step mortor to move in micro-Langmuir probe is 10um.[1-3] The used gas in this experiment is He-Ne-Xe (4%) mixure gas. And sustain voltage is 320V which is above of firing voltage for degradation. The electron temperature and plasma density can be obtained from current-voltage (I-V) characteristics of micro Langmuir probe, in which negative to positive bias voltage was applied to the probe. And Efficiency is calculated by formula related discharge power and light emission. Those experiments operated as various discharge time ($0{\sim}72$ Hours). As a result of this experiment, Electron Temperature was increased from 2eV to 5eV after discharge running time of 20 hours and saturates beyond 20 hours. The plasma density is inversely proportional to the square root of electron temperature. So the plasma density was decreased from $1.8{\times}10^{12}cm^{-3}$ to $8{\times}10^{11}cm^{-3}$ at above discharge running time. And the Efficiency was reduced to 70% at 60hours of discharge running time.