• Corrosion Science and Technology
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• 제16권3호
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• pp.100-108
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• 2017

In this investigation corrosion behavior of newly developed high-pressure die cast Al-Ni (N15) and Al-Ni-Ca (NX1503) alloys was studied in 3.5% NaCl solution. The electrochemical corrosion behavior was evaluated using open circuit potential (OCP) measurement, potentiodynamic polarization, and electrochemical impedance spectroscopy (EIS) techniques. Potentiodynamic polarization results validated that NX1503 alloy exhibited lower corrosion current density ($i_{corr}$) value ($5.969{\mu}A/cm^2$) compared to N15 ($7.387{\mu}A/cm^2$). EIS-Bode plots revealed a higher impedance (${\mid}Z{\mid}$) value and maximum phase angle value for NX1503 than N15 alloy. Equivalent circuit curve fitting analysis revealed that surface layer ($R_1$) and charge transfer resistance ($R_{ct}$) values of NX1503 alloy was higher compared to N15 alloy. Immersion corrosion studies were also conducted for alloys using fishing line specimen arrangement to simultaneously measure corrosion rates from weight loss ($P_W$) and hydrogen volume ($P_H$) after 72 hours and NX1503 alloy had lower corrosion rate compared to N15 alloy. The addition of Ca to N15 alloy significantly reduced the Al3Ni intermetallic phase and further grain refinement may be attributed for reduction in the corrosion rate.

• Progress in Superconductivity
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• 제11권2호
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• pp.106-111
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• 2010

Sapphire resonators with $YBa_2Cu_3O_{7-\delta}$ (YBCO) endplates have provided a way to realize extremely high quality factor due to the extremely low dielectric loss of sapphire and conductive loss of YBCO films, which enables to measure the low surface resistance of superconductor films at microwave frequencies. We present microwave properties of HTS sapphire resonators designed for measuring the surface resistance of HTS films at millimeter-wave frequencies by using the two-resonance mode dielectric resonator method. Despite enhanced surface resistance ($R_S$) of YBCO films due to the quadratic frequency dependence of the $R_S$, the unloaded quality factor ($Q_0$) of the $TE_{021}$ mode sapphire resonator still appears to be well above $1\;{\times}\;10^6$ at a mm-wave frequency of 38 GHz at 10 K. However, it appears that the $TE_{012}$ mode $Q_0$ is unexpectedly low despite that the corresponding resonance peak looks uncoupled with parasitic modes. We discuss possible reasons for the unexpected results using the surface resistance at the $TE_{021}$, $TE_{012}$, and $TE_{011}$ mode frequencies.

• The Journal of Advanced Prosthodontics
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• 제6권4호
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• pp.266-271
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• 2014

PURPOSE. The purpose of this study was to compare the fracture strength of the metal and the bond strength in metal-ceramic restorations produced by selective laser sintering (SLS) and by conventional casting (CAST). MATERIALS AND METHODS. Non-precious alloy (StarLoy C, DeguDent, Hanau, Germany) was used in CAST group and metal powder (SP2, EOS GmbH, Munich, Germany) in SLS group. Metal specimens in the form of sheets ($25.0{\times}3.0{\times}0.5mm$) were produced in accordance with ISO 9693:1999 standards (n=30). To measure the bond strength, ceramic was fired on a metal specimen and then three-point bending test was performed. In addition, the metal fracture strength was measured by continuing the application of the load. The values were statistically analyzed by performing independent t-tests (${\alpha}=.05$). RESULTS. The mean bond strength of the SLS group (50.60 MPa) was higher than that of the CAST group (46.29 MPa), but there was no statistically significant difference. The metal fracture strength of the SLS group (1087.2 MPa) was lower than that of the CAST group (2399.1 MPa), and this difference was statistically significant. CONCLUSION. In conclusion the balling phenomenon and the gap formation of the SLS process may increase the metal-ceramic bond strength.

• Nutrition Research and Practice
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• 제1권3호
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• pp.231-236
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• 2007

Underreporting patterns by the level of obesity have not been fully assessed yet. The purpose of this study was to examine the differential underreporting patterns on cardiovascular risk factor, macronutrient, and food group intakes by the level of Body Mass Index (BMI). We analyzed cross-sectional baseline nutritional survey data from the population-based longitudinal study, the Healthy Women Study (HWS) cohort. Study subjects included 538 healthy premenopausal women participating in the HWS. Nutrient and food group intakes were assessed by the one-day 24-hour dietary recall and a semi-quantitative food frequency questionnaire, respectively. The ratio of reported energy intake (EI) to estimated basal metabolic rate (BMR) was used as a measure of relative energy reporting status and categorized into tertiles. Overweight group ($BMI{\geq}25kg/m^2$) had a higher ratio of EI to BMR (EI/BMR) than normal weight group ($BMI<25kg/m^2$). Normal weight and overweight groups showed similar patterns in cardiovascular risk factors, nutrient intake, and food group intake by the EI/BMR. Fat and saturated fat intakes as a nutrient density were positively associated with the EI/BMR. Proportion of women who reported higher consumption (${\geq}4\;times/wk$) of sugar/candy, cream and red meat groups was greater in higher tertiles of the EI/BMR in both BMI groups. Our findings suggest similar patterns of underreporting of cardiovascular risk factors, and macronutrient and food group intakes in both normal and overweight women.

• 한국가금학회:학술대회논문집
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• 한국가금학회 2000년도 제17차 정기총회 및 학술발표
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• pp.91-93
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• 2000

Soybean meal(SMB) has not only been an important source of protein, but also a major source of isolfavones(IF) for poultry diet. Since the IF is one of effective phytoestrogens, evaluation of bioavailability of the phytochemicals for poultry and development of an animal model for assessment of the availability should be essential for its practical application. Present study was to develop bird model for assessing their bioavailability. No reports for such measurments with poultry could have every been found. Eight, 6-wk-old, layer-type, male birds were divided into two groups of four birds; normal (N) and colostomized(COL). Each bird was tube-fed a SMB sample at a level of 1% body weight. Samples from blood, urine and feces(COL birds) or urine+feces (N) were collected at 0, 2, 8, 15, 24 and 48 hours after the feeding. Plasma and urine samples were treated with -glucuronidase and fecal samples with 4N HCl for measurement of genistein(GE) and daidzein (DA) with HPLC set with an electrochemical detector. Maximum peaks of plasma IF appeared at 2 h after the meal for both birds groups. However the IF peak for N group was GE, while that for COL group was DA. Plasma DA levels for COL birds were always higher than those of GE, which was in opposite trend for N birds. This trend observed in the N birds is in accordance with those reported in rats fed SBM. In conclusion the results seem to suggest that colostomy as an attempt to separate urine from feces in birds affected the IF metabolism in the intestine and may not be a proper bird model to measure the IF bioavailability.

• Safety and Health at Work
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• 제11권1호
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• pp.109-117
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• 2020

Background: Ammonia and hydrogen sulfide are harmful gases generated during aerobic/anaerobic bacterial decomposition of livestock manure. We evaluated ammonia and hydrogen sulfide concentrations generated from workplaces at livestock farms and determined environmental factors influencing the gas concentrations. Methods: Five commercial swine farms and five poultry farms were selected for monitoring. Real-time monitors were used to measure the ammonia and hydrogen sulfide concentrations and environmental conditions during the manure-handling processes. Monitoring was conducted in the manure storage facility and composting facility. Information on the farm conditions was also collected through interview and walk-through survey. Results: The ammonia concentrations were significantly higher at the swine composting facilities (9.5-43.2 ppm) than at other manure-handling facilities at the swine and poultry farms, and high concentrations of hydrogen sulfide were identified during the manure agitation and mixing process at the swine manure storage facilities (6.9-19.5 ppm). At the poultry manure-handling facilities, the ammonia concentration was higher during the manure-handling processes (2.6-57.9 ppm), and very low hydrogen sulfide concentrations (0-3.4 ppm) were detected. The air temperature and relative humidity, volume of the facility, duration of manure storage, and the number of animals influenced the gas concentrations. Conclusion: A high level of hazardous gases was generated during manure handling, and some levels increased up to risk levels that can threaten workers' health and safety. Some of the farm operational factors were also found to influence the gas levels. By controlling and improving these factors, it would be possible to protect workers' safety and health from occupational risks.

• 한국지형학회지
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• 제25권2호
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• pp.15-29
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• 2018

The sediment transport process in a river reflects the process of geomorphological change in the watershed, influencesthe river bed variation and the river channel migration, and is a parametric phenomenon that exhibits a dynamic self-adjusting process. Sediment load is divided into bedload and suspended load depending on the dominant mechanism. Quantitative sediment load is important information for solving river problems. Because it is difficult and time consuming to measure bedload, compared to that ofsuspended load, data on the sediment transport load and the research required for the gravel-bed rivers are insufficient. This study is to analyze the ratio of the bedload to the total sediment load in gravel-bed rivers. The sediment load ratio in gravel-bed rivers increases with the flow rate per unit width, and the rate of the bedload varies more rapidly than the suspended load. The sediment transport efficiency coefficient has been affected by the ratio of the flow depth to the mean diameter of particles and has been dependent on the shear velocity Reynolds number. So $A^{\ast}$ and $B^{\ast}$ are introduced to compensate for the uncertainties such as bed materials, sediment transport, and flow velocity distribution, and the coefficient of bedload ratio has been presented. For the sediment load data in experimental channels and rivers, A* was 3.1. The dominant variables of $B^{\ast}$ were $u_*d_m/{\nu}$ in the gravel-bed and h/dm in the sand-bed. When $B^{\ast}$ the is the same, in the experimental channels the coefficient of bedload ratio was affected by the bed forms, but in the rivers it was of little difference between the gravel-bed and sand-bed.

• Journal of Animal Science and Technology
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• 제65권5호
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• pp.922-938
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• 2023

The current study was designed to evaluate the effect of sequential low and high dietary linseed oil (LO; as omega-3 enriched fatty acid; FA) before and post insemination, respectively, on different plasma variables of ewes. Fat-tailed Qezel ewes were assigned randomly to be fed a diet enriched with 3% LO (n = 30) or the saturated FA (SFA; n = 30) three weeks before insemination (Day 0). The lipogenic diet supplemented with 6% LO or SFA was fed after insemination until Day +21. The control ewes were fed an isocaloric and isonitrogenous diet with no additional FA during the study. Estrus was synchronized by inserting a vaginal sponge (Spongavet^®) for 12 days + 500 IU equine chorionic gonadotropin (eCG; Gonaser^®), and ewes were inseminated via laparoscopic approach 56-59 h after eCG injection. The size of ovarian structures was assessed by transvaginal ultrasonography at -21, -14, -2, 0, and +10 days. Blood samples were collected weekly to measure the plasma's different biochemical variables and FA profile. Treatment did not affect the amounts of glucose, aspartate aminotransferase, alanine aminotransferase, lactate dehydrogenase, interleukin-10, interleukin-2, and non-esterified FA (p > 0.05). Conversely, concentrations of triglyceride, cholesterol, tumor necrosis factor-alpha, and insulin-like growth factor-1 were higher in SFA-fed ewes relative to control animals (p < 0.05). LO feeding resulted in greater amounts of n-3 FA isomers in plasma, while higher amounts of stearic acid were detected in SFA fed group 0 and +21 (p < 0.05). The number of ovarian follicles and corpora lutea also were not affected by treatment. Other reproductive variables were not affected by treatment except for the reproductive rate. It seems that LO or SFA feeding of fat-tailed ewes peri-insemination period was not superior to the isocaloric non-additional fat diet provided for the control group during the non-breeding season.

• 한국지하수토양환경학회지:지하수토양환경
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• 제6권3호
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• pp.3-12
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• 2001

본 시험은 제주지역 화산회토에서 pressure-vacuum soil water sampler를 이용하여 시비 양분의 토양깊이별 이동상태를 조사하기 위하여 실시하였다. lysimeter(single chamber : model SW-071)를 각각 20, 40, 60, 80, 100, 120cm의 깊이에 매설한 후 전작물로는 옥수수, 후작물로는 감자를 재배하면서 강우시 침투수를 채수하여 pH및 양, 음이온의 농도를 조사하였다. 시비량은 질소-인산-가리를 옥수수는 36-30-30kg씩, 감자는 28-22-24kg씩 각각 파종전에 시용하였다. 채취한 침투수중 Cl, $NO_3$-N, $Ca^{+2}$, $K^{+}$의 평균농도는 시비 1개월 후에 20~40cm 깊이에서 급격하게 높아진 후 농도가 점차 낮아지면서 심토층으로의 하향 이동이 계속되어 5개월 후에는 시험 전 토양과 비슷한 수준이 되었다. 심토층(120cm)에서의 $NO_3$-N은 시비 1~l.5개월 후 그 농도가 가장 높았고, 다른 양이온도 비슷한 경향을 보였다. 용탈수의 PH와 $NO_3$-N은 부의 상관을 보였고, $NO_3$-N과 양이온간에는 고도의 정의 상관을 보여 $NO_3$-N이 표토에서 심토층으로 하향이동시 $Ca^{+2}$, $K^{+}$, $Mg^{+2}$ 등의 양이온도 동반용탈되는 것으로 조사되었다.

• 한국방사선학회논문지
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• 제13권4호
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• pp.653-659
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• 2019

본 연구는 고용량 $^{131}I$ 치료 후 방사선원이 된 퇴원 환자로부터 나오는 방사선 피폭에 관해 외부 선량률을 측정하고, 그에 따른 피폭선량을 예측하는 것이 목적이다. 200 mCi 이상 고용량 $^{131}I$ 치료를 받은 30명의 환자에서 구리링 3개를 이용하여 환자로부터 거리 및 방위각에 따른 선량평가를 시행하였다. 정확한 방사선 계측을 위하여 GM 계측기를 이용하여 2명의 측정자가 방위각 8 포인트와 거리 변화를 주며 계측하였다. 측정값을 기반으로 3가지 예측 시뮬레이션을 설정하여 불특정 다수 일반인에 대한 피폭선량을 계산하였다. 1m 높이에서 방위각에 따른 외부 선량률이 가장 높은 부위는 0도이다. 거리에 따른 선량률은 거리별 방위각의 선량률 평균값을 사용하였다. 거리에 따른 외부 선량률의 최고치는 50, 100, 150 cm에서 각각 $214{\pm}16.5$, $59{\pm}9.1{\mu}Sv/h$, $38{\pm}5.8{\mu}Sv/h$ 이다. 고용량 $^{131}I$ 치료 환자가 대중교통을 이용해서 5시간 이동할 때 반경 50 cm 지점의 옆좌석에 안은 불특정 일반인이 받을 수 있는 피폭선량은 1.14 mSv이다. 소변 통(urin bag)을 착용한 퇴원환자로부터 100 cm 거리에서 4일 동안 간병인이 받을 수 있는 최대 피폭선량은 6.5 mSv이다. 퇴원 환자 귀가로 인해 7일 동안 150 cm 거리에서 보호자가 받을 수 있는 최대 피폭선량은 1.08 mSv이다. 개발된 예측 모델링으로 불특정 $^{131}I$ 치료 환자의 주변 일반인에게 적용하였을 때 연간 선량 한도를 단시간에 초과하는 수준이었다. 따라서 본 연구를 통해 현행 고용량 $^{131}I$ 치료 환자의 퇴원 후 주변의 일반인의 방호체계의 합리적인 가이드라인을 제시하는 데 도움을 줄 수 있을 것으로 사료된다.