• Nuclear Engineering and Technology
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• 제30권2호
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• pp.112-127
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• 1998

The present study is to assess the applicability of the best-estimate thermal-hydraulic codes, RELAP5/MOD3.2 and CATHARE2V1.3U, to the analysis of thermal-hydraulic behavior in PWRs during midloop operation following the loss of RHRS. The codes simulate an integral test, BETHSY 6.94, which was conducted in the large scale test facility of BETHSY in France. The test represents the accident where the loss of RHRS occurs during midloop operation with the pressurizer and upper head vents open and the sight level indicator broken. Besides, the hot legs are half filled with water and the upper parts of the primary cooling system are filled with nitrogen, with a letdown line open and only one SG available. The purposes of this study are to understand the physical phenomena associated with reflux cooling in the 5G U-tubes when noncondensable gas is present under low pressure and to assess the applicability of the codes to simulate the loss of RHRS event by comparing the predictions with the test results. The results of the study may contribute to actual applications for plant safety evaluation and description of the emergency operating procedure.

• Asian-Australasian Journal of Animal Sciences
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• 제32권8_spc호
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• pp.1296-1305
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• 2019

There have been recent advances concerning research of the feeding and nutrition of dairy goats in a wide array of areas. Ruminally emitted methane and supplementary feedstuffs to a lesser extent make appreciable contributions to the carbon footprint of dairy goats, with the former affected by type of production system and associated dietary characteristics. Unique behavior of goats necessitates careful consideration of the nature of confinement facilities to achieve optimal production by animals differing in social hierarchy. Physiological conditions such as nutritional needs and perhaps health status may influence diet selection by goats in both grazing and confinement settings. Some research suggests that low concentrations of protein and fat in milk of high-yielding dairy goat breeds could involve the type and nature of dietary ingredients as influencing end products of ruminal fermentation. With the relationship between milk urea nitrogen concentration and efficiency of dietary protein utilization, through future research the measure may be a useful tool for diet formulation as in dairy cattle. Effects of dietary inclusion of sources of fats and oils vary considerably depending on their nature, as is also true for byproduct feedstuffs and conventional ones being substituted for. Supplementation of dairy goats with sources of polyunsaturated fatty acids can affect oxidative stress and various feedstuffs influence antioxidant status; however, research addressing the significance of such changes under practical production settings would be beneficial.

• 센서학회지
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• 제28권1호
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• pp.47-51
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• 2019

Sweat-based glucose sensors are being widely investigated and researched as they facilitate painless and continuous measurement. However, because the concentration of sweat glucose is almost a hundred times lower than that of blood glucose, it is important to develop electrochemical sensing electrode materials that are highly sensitive to glucose molecules for the detection of low concentrations of glucose. The preparation of a flexible and ultra-sensitive sensor for detection of sweat glucose is presented in this study. Oxygen and nitrogen are removed from the surface of a polyimide film by exposure to a CO2 laser; hence, laser-induced graphene (LIG) is formed. The fabricated LIG electrode showed favorable properties of high roughness and good stability, flexibility, and conductivity. After the laser scanning, Pt nanoparticles (PtNP) with good catalytic behavior were electrodeposited and the glucose sensor thus developed, with a LIG/PtNP hybrid electrode, exhibited a high order of sensitivity and detection limit for sweat glucose.

• Bulletin of the Korean Chemical Society
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• 제8권4호
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• pp.225-230
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• 1987

The redox properties of 2-mercaptopyridine N-oxide (mpno) and its oxovanadium complex, $VO (mpno)_2$ have been studied by the use of polarography and cyclic voltammetry. The radical anion of mpno is generated in acetone and is adsorbed to the electrode to form an adsorption wave at -0.21 V vs Ag/AgCl electrode. The normal wave appeared at -0.50 V is attributed to the formation of radical anion. The $VO (mpno)_2$ exhibits one oxidation wave at +0.57 V, and two reduction waves at -1.07 V and -1.76 V vs. Ag/AgCl electrode; the oxidation is fully reversible one-electron process ($VO (mpno)_2\;{\leftrightarrow}\;VO(mpno)_2^+ + e).$ The reduction wave at -1.07 V is quasireversible and is arised from the formation of $VO (mpno)_2^-.$ The second reduction wave at -1.76 V is irreversible and this reduction process consists of two one-electron steps. The sulfur containing ligands seem to enhance the stability of lower oxidation state of vanadium while the oxygen or nitrogen donor of the ligands stabilize the higher oxidation state of vanadium when comparisons are made among several oxovanadium complexes.

• 대한금속재료학회지
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• 제49권3호
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• pp.203-210
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• 2011

Bake hardening steels have to resist strain aging to prevent the yield strength increment and stretcher strain during press process and to enhance the bake hardenability during baking process after painting. The bake hardening steels need to control the solute carbon and the solute nitrogen to improve the bake hardenability. Ti and/or Nb alloying for nitride and carbide precipitation and low carbon content below 0.003% are used to solve strain aging and formability problem for automotive materials. However, in the present study, the effect of micro-precipitation of copper sulfide on the bake hardenability and fatigue properties of extremely low carbon steel has been investigated. The bake hardenability of Cu-alloyed bake hardening (Cu-BH) steel was slightly higher (5 MPa) than that of Nb-alloyed bake hardening (Nb-BH) steel, but the fatigue limit of Cu-BH steel was far higher (45 MPa) than that of Nb-BH steel. All samples showed the ductile fracture behavior and some samples revealed distinct fatigue stages, such as crack initiation, stable crack growth and unstable crack growth.

• 한국안전학회지
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• 제36권2호
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• pp.18-25
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• 2021

Specialty contractor facilities, which involve a combination of welding and commissioning, face a high risk of serious accidents such as fire, explosion, and suffocation associated with welding work, nitrogen, and argon use. In such facilities, the organizational safety culture has considerable impact on the frequency of accidents. In this study, a safety culture evaluation was conducted on specialty contractors. NOSACQ-50, a standardized survey method on safety culture, was selected as an assessment tool to evaluate the safety culture in specialized construction companies that could not afford to invest heavily in safety. The self-administered questionnaire survey was conducted with 201 workers of four construction companies and the results were analyzed. It was found that in companies with low safety culture, the occurrence of irrationality was 66.0%, while in companies with high safety culture, the occurrence of irrationality was 42.6%. Thus, the difference in the occurrence of irrationality by safety culture was statistically significant. The difference in safety culture level according to the experience of occurrence of irrationality was also significant. It was also found that the higher the belief in safety management authorization, safety responsibilities of managers, worker safety priorities, and safety system effects, the lower the probability of irrationality.

• Elastomers and Composites
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• 제58권3호
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• pp.121-127
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• 2023

The effect of diisocyanate type on the decomposition temperature of polyurethane (PU) hydrolysis was investigated in a subcritical water medium up to 250℃. PU samples were prepared using different types of diisocyanate: two aromatic diisocyanates (4,4'-methylene diphenyl diisocyanate (MDI) and methyl phenylene diisocyanate (TDI)), one unbranched aliphatic diisocyanate (hexamethylene diisocyanate (HDI)), and two cyclic aliphatic diisocyanates (4,4'-methylene dicyclohexyl diisocyanate (H₁₂MDI) and isophorone diisocyanate (IPDI)). The pressure had no effect on hydrolysis in the range of 70-250 bar. The decomposition temperature of the PU samples increased in the following order: TDI-PU (199℃) < H₁₂MDI ≈ IPDI ≈ HDI (218-220℃) < MDI-PU (237℃). This order of increase in temperature is related to the electron-donating ability of the group to connected to the nitrogen of the urethane unit. When the temperature of the (PU + water) mixture reached the specific decomposition temperature, the PU samples hydrolyzed completely within 5 min into primary amine and 1,4-butanediol. The hydrolysis products from MDI-PU and H₁₂MDI-PU were separated into a liquid phase rich in (BD + water) and a solid low phase rich in amine, whereas the products from TDI-, IPDI-, and HDI-PU existed in a single aqueous phase.

• 가정∙방문간호학회지
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• 제31권1호
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• pp.66-76
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• 2024

Purpose: This study aimed to develop and evaluate an integrated management program to enhance self-efficacy, compliance with sick-role behaviors, symptom management, and biomarker indication in hemodialysis patients. Methods: The integrated management program was developed through a systematic review of literature, analysis of relevant online data, and expert validation. It comprised 480 min of video-based education delivered eight times over four weeks, supplemented by weekly phone consultations and text message support from a nurse. To evaluate the program's effectiveness, it was administered to 44 patients with hemodialysis in a single group in a pre-post test experimental study. Changes in self-efficacy, sick-role behavior compliance, dialysis symptom index, and biomarkers were assessed. Results: The program yielded statistically significant improvements in self-efficacy (t=-7.13, p<.001), sick-role behavioral compliance (t=-7.35, p<.001), dialysis symptom index (t=4.32, p<.001), and blood urea nitrogen levels (t=2.55, p=.014) among the participants. Conclusion: The integrated management program is an effective intervention for improving hemodialysis patients' self-efficacy, compliance with sick-role behaviors, and experience of symptoms. Additionally, it is considered an intervention with high clinical applicability and efficiency through video reproducibility.

• 한국수정란이식학회지
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• 제22권1호
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• pp.15-19
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• 2007

본 연구는 번식 효율 증진을 위해 BCS, BUN과 발정 발현과의 관계를 조사하였으며, 공시된 홀스타인 젖소 51두 중 37두에서 배란 및 28두에서 발정 발현을 확인하였다. 발정 유기율에서 BCS $2.0{\sim}2.49$와 $2.5{\sim}3.0$인 우군에서는 각각 78.9% 및 73.9%인 반면 2.0 미만인 우군에서는 55.6%로 유의적인(p<0.05)차이를 보였으며, 발정 발현율과 승가 허용율에서도 BCS $2.0{\sim}2.49$인 우군에서 각각 73.3% 및 46.7%이고 BCS $2.5{\sim}3.0$인 우군은 각각 88.2% 및 64.7%를 보인 반면 BCS 2.0 미만인 우군에서는 각각 40% 및 0%로 BCS 2.0 이상인 우군에 비해 유의적(p<0.05)으로 낮게 나타났다. 발정 동기화 우군의 BUN과 발정 발현율과의 관계에서 BUN 수준이 10mg/dl 이상인 우군에서 85.7%의 발정 발현율를 보인 반면 10 mg/dl 이하인 우군에서는 52.1%로 유의적으로(p<0.05) 낮게 나타났다. 발정 행동별(외음부 냄새 맡기, 턱비빔, 승가 및 승가 허용) BUN 수준에 있어서는 영향을 미치지 않는 것으로 나타났다. 발정 발현율과 BUN 수준은 초산우와 2산 이상우 사이에서 유의적인 차이를 보이지 않았다. 본 연구의 결과 BCS와 BUN 수준이 낮으면 발정 발현에 영향을 미치는 것을 알 수 있다. 발정 발현율이 점차 떨어지고 있는 현 시점에서 효율적인 영양관리가 뒷받침되어야 번식 효율이 향상될 것으로 생각된다.

• 청정기술
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• 제25권3호
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• pp.231-237
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• 2019

연속 유입식 SBR 공정의 BOD 제거효율은 체류 시간 9 ~ 15 h에서는 92.1 ~ 96.0%에서 체류 시간 6 h에서는 86.9 ~ 90.7%로 감소하였으나, 체류 시간 6 h까지 안정적인 제거효율을 보였다. T-N 제거효율은, 체류시간 12 ~ 15 h에서는 80.1 ~ 87.9%, 체류시간 9 h에서는 71.9 ~ 87.0%, 체류시간 6 h에서는 60.1 ~ 65.7%로 감소되었다. 유기물 및 질소 제거 결과 실험결과 연속 유입식 SBR 반응조의 최적 체류시간은 9 h로 판단된다. 체류시간 9 h에서 반송률(1 ~ 5Q) 변화에 따른 유기물 제거효율 검토 결과, TCODcr의 제거율은 88.4 ~ 96.0%, TBOD 제거효율은 92.1 ~ 98.1%로 조사되어 내부반송률 변화가 유기물 제거에 미치는 영향은 미미한 것으로 조사되었다. 내부반송률 변화에 따른 T-N은 1 ~ 2Q에서 70.3 ~ 80.4%, 3Q는 77.2 ~ 85.6%, 4 ~ 5Q는 61.5 ~ 80.8%로 조사되어, 내부반송률 3Q에서 질소 제거효율이 가장 높게 조사되었다. T-P는 1 ~ 4Q에서 제거효율은 75.0 ~ 84.6%, 5Q에서는 63.3 ~ 72.4%로 감소하였는데, 이러한 이유는 반송률 5Q 이상에서는 미생물에 의한 인(P)의 용출 및 섭취가 원활하게 이루어지지 않기 때문으로 판단된다. 따라서 유기물 및 영양염류 제거를 위한 최적 반송률은 3Q로 조사되었다.