• Journal of Bio-Environment Control
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• v.27 no.1
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• pp.20-26
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• 2018

This study was conducted to develop a device for measuring the air flow by space variation through monitoring program, which acquires data by each point from each environmental sensor located in the greenhouse. The distribution of environmental factors(air temperature, humidity, wind speed, etc.) in the greenhouse is arranged at 12 points according to the spatial variation and a large number of measurement points (36 points in total) on the X, Y and Z axes were selected. Considering data loss and various greenhouse conditions, a bit rate was at 125kbit/s at low speed, so that the number of sensors can be expanded to 90 within greenhouse with dimensions of 100m by 100m. Those system programmed using MATLAB and LabVIEW was conducted to measure distributions of the air flow along the greenhouse in real time. It was also visualized interpolated the spatial distribution in the greenhouse. In order to verify the accuracy of CFD modeling and to improve the accuracy, it will compare the environmental variation such as air temperature, humidity, wind speed and $CO_2$ concentration in the greenhouse.

• Economic and Environmental Geology
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• v.53 no.2
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• pp.147-157
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• 2020

Mass change in the Antarctic Ice Sheet(AIS) is the most important indicator of changes in Earth's climate system including global mean sea level rise that are largely affected by ongoing global warming. In this study, AIS mass variations are examined with satellite gravity data and outputs from a regional climate model. The analysis of gravity data shows that along the coastal region the Western AIS has experienced a continuous and significant ice loss while a slight increasing in the Eastern AIS during the study period (2002.08-2016.08). The temporal and spatial variations in ice mass changes are recovered by a regional climate model, but the recovered amplitudes are much smaller than those of observations. This under-estimation is remarkably resolved by modifying a base flow field for the ice discharge. The recovered estimates based on the ice-flow field can explain about 97% of the rate of mass change in observations before 2009. This implies that changes in ice flow dynamics along the coast line plays a pivotal role in regulating long-term budget of ice mass in AIS.

• Clean Technology
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• v.26 no.1
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• pp.22-29
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• 2020

Recently, as the fine dust is increased and the emission regulations of diesel engines have been tightened, interest in diesel soot filtration devices has rapidly increased. There is specifically a demand for the technological development of higher diesel exhaust gas after-treatment device efficiency. As part of this, many studies were conducted to increase exhaust gas treatment efficiency by improving the flow uniformity of the exhaust gas in the diesel particulate filter (DPF) and reducing the pressure drop between the inlet and the outlet of DPF. In this study, the effects of pressure drop by the flow rate and temperature of exhaust gas, DPF I/O ratio, Ash, and PM amount in diesel reduction device were simulated via a 12" diameter DPF and diesel oxidation catalyst (DOC) using ANSYS Fluent. As the flow rate and temperature decreased, the pressure drop decreased, whereas the PM amount affected the pressure drop more than the ash amount and the pressure drop was lower in anisotropic DPF than isotropic DPF. In the case of DPF flow uniformity, it was constant regardless of the various variables of DPF. In ESC and ETC conditions, the filtration efficiency for PM was similar regardless of anisotropic and isotropic DPF, but the filtration efficiency for PN (particle number) was higher in anisotropic DPF than isotropic DPF.

• Nuclear Engineering and Technology
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• v.52 no.8
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• pp.1756-1763
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• 2020

The paper studies spark plasma sintering (SPS) of industrially used UO₂-based fuel containing integral fuel burnable absorber (IFBA) of neutrons Gd₂O₃. Densification dynamics of pristine UO₂ powder and the one added with 2 and 8 wt% of Gd₂O₃ under ultrasonication in liquid has been studied under SPS conditions at 1050, 1250, and 1450 ℃. Effect of sintering temperature on phase composition as well as on O/U stoichiometry has been investigated for UO₂ SPS ceramics. Sintering of uranium dioxide added with Gd₂O₃ yields solid solution (U,Gd)O₂, which is isostructural to UO₂. SEM with EDX and metallography were implemented to analyze the microstructure of the obtained UO₂ ceramics and composite UO₂-Gd₂O₃ one, particularly, open porosity, defects, and Gd₂O₃ distribution were studied. Microhardness, compressive strength and density were shown to reduce after addition of Gd₂O₃. Obtained results prove the hypothesis on formation of stable pores in the system of UO₂-Gd₂O₃ due to Kirkendall effect that reduces sintering efficiency. The paper expands fundamental knowledge on pros and cons of fuel fabrication with IFBA using SPS technology.

• Science of Emotion and Sensibility
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• v.8 no.2
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• pp.95-101
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• 2005

This study is based on previous information regarding reduced cardiac vagal activity in patients with coronary artery disease(CAD), on reduced variance(SDNN : standard deviation of all normal RR intervals), low-frequency power(LF), and the complexity of heart rate variability(HRV) in patients with chronic heart failure(CHF), and on the normalized high-frequency power of HRV is the highest in the right lateral decubitus position among 3 recumbent postures in patients with CAD, However, nothing is known about the nonlinear dynamics of HRV for the 3 recumbent postures in patients with CAD. To investigate the linear and non-linear characteristics of HRV in patients with CAD, 29 patients as CAD group and 23 patients as control group were studied. Electrocardiogram(ECG) with lead II channel was measured on these patients for 3 recumbent postures in random order. The HRV from ECG was analyzed with linear method(for time and frequency domains) and nonlinear method. The lower the high-frequency power in normalized unit(nHF) in the supine or left lateral decubitous position, the higher the increase in nHF when the position was changed from supine or left lateral decubitous to right lateral decubitous. Among the 3 recumbent postures in patients with severe CAD, the right lateral decubitus position was observed to induce the highest vagal modulation, the lowest sympathetic modulation, and the highest complexity of human physiology system.

• BMB Reports
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• v.31 no.6
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• pp.590-594
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• 1998

X-ray crystallographic studies of the deoxy form of human adult hemoglobin (Hb A) have shown that ${\beta}99Asp$ is hydrogen bonded to both ${\alpha}42Tyr$ and ${\alpha}97Asn$ in the ${\alpha}_1{\beta}_2$ subunit interface, suggesting that the essential role of ${\beta}99Asp$ is to stabilize the deoxy-Hb by creating the intersubunit hydrogen bond. In particular, for Hb Kempsey (${\beta}99Asp{\rightarrow}Asn$), molecular dynamics simulation indicated that a new hydrogen bond involving ${\beta}99Asn$ can be induced by replacing ${\alpha}42Tyr$ with a strong hydrogen-bond acceptor such as Asp. Designed mutant recombinant (r) Hb (${\beta}99Asp{\rightarrow}Asn$, ${\alpha}42Tyr{\rightarrow}Asp$) have been produced in the Escherichia coli expression system and have shown that functional defects of Hb Kempsey could be compensated by the ${\alpha}42Tyr{\rightarrow}Asp$ substitution. However, as the ${\alpha}42 Tyr{\rightarrow}Asp$ mutation has never been reported before, it is still possible that the functional properties of r Hb (${\beta}99Asp{\rightarrow}Asn$, ${\alpha}42Tyr{\rightarrow}Asp$) may be due to the mutation itself. Thus, it is required to produce r Hb (${\alpha}42Tyr{\rightarrow}Asp$) and r Hb Kempsey (${\beta}99Asp{\rightarrow}AsnX$( as controls, and to compare their properties with those of r Hb (${\beta}99Asp{\rightarrow}Asn$, ${\alpha}42Tyr{\rightarrow}Asp$). r Hb (${\alpha}42Tyr{\rightarrow}Asp$) could not be purified because it is an unstable hemoglobin which forms Heinz bodies. r Hb Kempsey (${\beta}99Asp{\rightarrow}Asn$) exhibits very high oxygen affinity and greatly reduced cooperativity. Thus, r Hb (${\beta}99Asp{\rightarrow}Asn$) and r Hb (${\alpha}42Tyr{\rightarrow}Asp)$ compensate each other.

• Biomedical Science Letters
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• v.6 no.4
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• pp.229-235
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• 2000

In situ brain-pancreas perfusion was performed on male adult Sprague-Dawley rats, of which the central nervous systems (CNS) were intact during the perfusion procedure. The modified Krebs-Ringer buffer with 100 mg/dL of glucose and 20 mM of arginine was perfused for 30 min. In the experimental groups, a cephalic glucopenia was induced at 0 min (GLP1 group) or at 16 min (GLP2 group). The glucopenia was not induced in the control (CONT group). Insulin and glucagon concentrations in the effluent samples from the pancreas were measured using a RIA method. In all three groups, the first and second phases in the dynamics of the insulin and glucagon secretion were observed, which was a typical biphasic secretory pattern. The amount of insulin secretion tended to decrease in the GLP1 and GLP2 groups, but there was no statistically significant difference among the groups. However, the amount of glucagon secretion during 0~15 min of the perfusion period in the GLP1 group was greater as compared to the CONT group (p<0.05). The amount of glucagon secretion during 16~30 min of the perfusion period in the GLP2 group tended to be greater as compared to the CONT group, however there was no statistical significance. These data indicate that the cephalic glucopenia stimulates the direct secretion of glucagon from the pancreas during the early period of perfusion in the CNS-intact pancreatic perfused rats.

• Journal of Advanced Marine Engineering and Technology
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• v.40 no.6
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• pp.484-492
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• 2016

The turbine is an important component and has a significant impact on the thermodynamic efficiency of the organic Rankine cycle. A precise preliminary design is essential to developing efficient turbines. In addition, performance analysis and structural analysis are needed to evaluate the performance and structural safety. However, there are only a few exclusive studies on the development process of the radial inflow turbines for the organic Rankine cycle (ORC). In this study, a preliminary design of the ORC radial inflow turbine was performed. Subsequently, the performance and structural analysis were also carried out. The RTDM, which was developed as an in-house code, was used in the preliminary design process. The results of the performance analysis were found to be in good agreement with target performances. Structural analysis of the designed turbine was also carried out in order to determine whether the material selection for this study is suitable for the flow conditions of the designed turbine, and it was found that the selected aluminum alloy is suitable for the designed turbine. However, the reliability of the preliminary design algorithms and numerical methods should be strictly verified by an actual experimental test.

• Fire Science and Engineering
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• v.26 no.3
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• pp.21-28
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• 2012

The objective of this study is to evaluate the prediction accuracy of FDS(Fire Dynamic Simulator) for the thermal and chemical characteristics of under-ventilated fire with unsteady fire growth in a semi-closed compartment. To this end, a standard doorway width of the full-scale ISO 9705 room was modified to 0.1 m and the flow rate of heptane fuel was increased linearly with time (until maximum 2.0 MW based on ideal heat release rate) using a spray nozzle located at the center of enclosure. To verify the capability of FDS, the predicted results were compared with a previous experimental data under the identical fire conditions. It was observed that with an appropriate grid system, the numerically predicted temperature and heat flux inside the compartment showed reasonable agreement with the experimental data. On the other hand, there were considerable limitations to predict accurately the unsteady behaviors of CO and $CO_2$ concentration under the condition of continuous fire growth. These results leaded to a discrepancy between the present evaluation of FDS and the previous evaluation conducted for steady-state under-ventilated fires. It was important to note that the prediction of transient CO production characteristics using FDS was approached carefully for the under-ventilated fire in a semi-closed compartment.

• Sleep Medicine and Psychophysiology
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• v.5 no.2
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• pp.185-193
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• 1998

Objectives : The hypothesis that the brain is a nonlinear dynamical system exhibiting deterministic chaos has offered new perspectives to the investigation of information processing in the brain of schizophrenic patients. It seemed worthwhile to estimate nonlinear measures of the electroencephalogram (EEG) in positive and negative schizophrenics, because nonlinear measures might serve as indicators of the specific brain function in schizophrenia according to specific psychopathologies. Method : Previous studies which estimated the chaoticity in the brain of schizophrenia with nonlinear methods recorded the EEGs at limited electrodes, so we tried to record EEGs from 16 channels for nonlinear analysis in 8 positive and 9 negative schizophrenics and 8 healthy control subjects. We employed a new method to calculate the nonlinear invariant measures. For limited noisy data, this algorithm was strikingly faster and more accurate than previous ones. Results : Our results showed that the patients with negative schizophrenia had lower the first positive Lyapunov exponents ($L_1$) than the positive schizophrnics and control subjects at $T_3$ lead. Positive symptoms were positively correlated with $L_1$ in $C_3,\;O_1$ leads, and negatively correlated with $C_4$ lead. Conclusion : These results suggest that if clinical variables such as psychopathology or neuroleptic medications would be well controlled, the nonlinear analysis of the EEGs in patients with schizophrenia seems to be a useful tool in analyzing EEG data to explore the neurodynamics.