• Nuclear Engineering and Technology
• /
• 제55권7호
• /
• pp.2712-2722
• /
• 2023

For an accurate and efficient time-dependent Monte Carlo (TDMC) neutron transport analysis, several advanced methods are newly developed and implemented in the Seoul National University Monte Carlo code, McCARD. For an efficient control of the neutron population, a dynamic weight window method is devised to adjust the weight bounds of the implicit capture in the time bin-by-bin TDMC simulations. A moving geometry module is developed to model a continuous insertion or withdrawal of a control rod. Especially, the history-based batch method for the TDMC calculations is developed to predict the unbiased variance of a bin-wise mean estimate. The developed methods are verified for three-dimensional problems in the C5G7-TD benchmark, showing good agreements with results from a deterministic neutron transport analysis code, nTRACER, within the statistical uncertainty bounds. In addition, the TDMC analysis capability implemented in McCARD is demonstrated to search the optimum detector positions for the pulsed-neutron-source experiments in the Kyoto University Critical Assembly and AGN201K.

• 한국가금학회지
• /
• 제31권3호
• /
• pp.137-143
• /
• 2004

The fractional synthesis rates(FSR) were measured with 2l-wk and 3l-wk-old broiler breeder pullets and hens to investigate the effect of sexual maturity on FSR. The FSR were obtained from chicken tissues and blood samples using High-Performance Liquid Chromatography/Mass Spectrometry(HPLC/MS). A L-l-13C, 15N -leucine saline solution was infused by bolus injection as a tracer into broiler breeder pullets in the experiment. A rapid HPLC/MS method was developed to measure the isotopic enrichments of leucine in plasma, tissue samples, and eggs. The enrichments of stable isotope leucine incorporated into protein and the enrichments of the stable isotope free leucine were measured in liver, breast muscle and blood samples. Two sets of experiments were conducted. In experiment one, 2l-wk-old, sexually immature broiler breeder pullets were divided into groups of three and blood samples were collected at 20 or 30 min intervals until 1.5 h from initial injection. The pullets were sacrificed in groups of three at varying time intervals for 7 h after injection. The liver, breast muscle and blood samples were removed for analysis. The FSR were estimated to be 8.7l%/day for liver, 4.06％/day for breast muscle, and 5.08％/day for blood samples in 30 minutes after injection from the enrichment ratios. In experiment two, sexually matured 3l-wk-old broiler breeder hens were assorted into groups of three and blood samples were obtained at 20 or 30 min intervals for 2 h. The FSR for blood samples were determined. The broiler breeder hens were sacrificed in groups of three at various time intervals until 7 h after injection and liver, breast muscle and blood samples were removed for analysis. The FSR were calculated to be 5.96％/day for liver. Eggs were collected from five chickens daily for 10 days after large bolus injection. The average of total enrichments of stable isotope in egg albumin was increased by 0.064% at 4 days after injection and was back to normal in 7 days.

• Biomolecules & Therapeutics
• /
• 제22권2호
• /
• pp.161-165
• /
• 2014

The main purpose of this study was to develop a novel, in situ gel system for sustained delivery of ranitidine hydrochloride. Ranitidine in situ gels at 0.2%, 0.5%, and 1.0% gellan gum concentration (w/v) were prepared, respectively, and characterized in terms of preparation, viscosity and in vitro release. The viscosity of the gellan gum formulations in solution increased with increasing concentrations of gellan gum. In vitro study showed that the release of ranitidine from these gels was characterized by an initial phase of high release (burst effect) and translated to the second phase of moderate release. Single photon emission computing tomography technique was used to evaluate the stomach residence time of gel containing $^{99m}Tc$ tracer. The animal experiment suggested in situ gel had feasibility of forming gels in stomach and sustained the ranitidine release from the gels over the period of at least 8 h. In conclusion, the in situ gel system is a promising approach for the oral delivery of ranitidine for the therapeutic effects improvement.

• Nuclear Engineering and Technology
• /
• 제31권4호
• /
• pp.423-431
• /
• 1999

A radiotracer technique has been developed to monitor the rotational movement of two piston rings in one cylinder during engine operation. The rings were labeled with two different kinds of radioisotopes, i.e. $^{60}$ Co and $^{192}$ Ir, for identification of the top ring from the second ring. The radiotracers were implanted in a small hole bored on the inner side of each piston ring. The rings were installed in a single cylinder hydrogen engine and three Nal scintillation detectors were mounted around the engine block to measure the gamma radiation. The angle of ring-gap orientation was determined from the radiation counts measured with the three detectors during engine operation. Two windows (upper window for $^{60}$ Co and lower window for $^{192}$ Ir) were set on each ratemeter to count radiation from the two isotopes separately. Procedure to convert the radiation counts to the position of the ring gap was established. With the software programmed with MS-Visualbasic, radiation counts were compared with the reference responses that were measured at angular intervals of 10$^{\circ}$for each piston ring in advance of the experiment. The result was used for the evaluation of the relationship between the orientation of ring-gaps and oil consumption. It was found that an increase in the oil consumption rate of a specific operation condition was closely related to the relative phase angle of the two piston rings.

• International Journal of Aeronautical and Space Sciences
• /
• 제12권3호
• /
• pp.296-304
• /
• 2011

In order to design a shear coaxial injector of solid particles with water, basic experiments on a particle laden jet are necessary. The purpose of the present study is to understand the effect of particle loading ratio on the particle spray characteristics (i.e. spreading angle, distribution of particle number density, velocity profiles, and particle developing region length). Hydro-reactive Al2O3 particles with a primary particle diameter of 35~50 ${\mu}m$ are used in this experiment. An automated particle feeder was designed to supply constant particle mass flowrates. Air is used as the carrier gas. To determine the air velocity at the orifice exit, tracers (aluminum oxide, 0.5~2 ${\mu}m$ primary diameter) are also supplied by a tracer feeder. A plain orifice type injector with 3 mm diameter, and 20 mm length was adopted. Particle image velocimetry is used to measure the mean and fluctuating velocity components along the axial and radial directions.

• 한국기계가공학회지
• /
• 제20권4호
• /
• pp.94-105
• /
• 2021

A graphical user interface (GUI) program for steam tracing system selection was developed by using a theoretical model. We derived the model on the basis of the one-dimensional heat transfer theory of conduction and convection through a composite wall. Computational fluid dynamics (CFD) and experiments were performed for validation at steam temperatures of 120.4[℃] and 158.9[℃]. The temperature of a pipe's outer surface obtained through CFD matched well with that predicted by the proposed model for both conditions. By contrast, the experiment results showed a small error at 120.4[℃] and a large error at 158.9[℃] because of the melting of the heat transfer compound and water phase transition. Thus, the steam temperature range of the proposed model is below 120.4[℃].

• Nuclear Engineering and Technology
• /
• 제53권1호
• /
• pp.79-92
• /
• 2021

Venturi tube is based on turbulent flow, whereby the microbubbles can be generated by the turbulent fragmentation. This phenomenon is common in several venturi bubblers used by the nuclear, aerospace and chemical industries. The first objective of this paper is to study the liquid-phase velocity field experimentally and develop correlations for the turbulent quantities. The second objective is to research velocity field characteristics theoretically. Stereoscopic PIV measurements for the velocity field have been analyzed and utilized to develop the turbulent kinetic energy in the venturi tube. The tracking properties of the tracer particles have been verified enough for us to analyze the turbulence field. The turbulence kinetic energy has a bimodal distribution trend. Also, the results of turbulence intensity along the horizontal direction is gradually uniform along the downstream. Both the mean velocity and the fluctuation velocity are proportional to the Reynolds number. Besides, the distribution trend of the mean velocity and the velocity fluctuation can be determined by the geometric parameters of the venturi tube. An analytical function model for the flow field has been developed to obtain the approximate analytical solutions. Good agreement is observed between the model predictions and experimental data.

• Applied Biological Chemistry
• /
• 제20권2호
• /
• pp.255-261
• /
• 1977

Zn-65 추적자를 이용하여 아연비료의 효율을 평가하기 위해서 산성인 김포토양과 알카리성인 영월토양을 사용하여 pot 실험을 수행하였다. 아연원은 황산아연 탄산아연 염화아연 그리고 산화아연을 이용했고 고저의 두가지 수준으로 처리했으며 사용방법은 토양전체에 혼합하는 방법, 토양표면 또는 관개수에 뿌리는 병과 이양시 수도의 뿌리를 산화아연 용액에 담그는 법을 시도했다. 알카리성인 영월토양이 산성인 김포토양보다 아연비료의 효율이 컸으며 특히 이양후 초기에는 영월토양에서 아연비료의 시용이 필수적임을 알았다. 아연의 처리 방법으로는 토양에 혼합해주는 것이 가장 효과적이었으며 수도근을 아연 용액에 담그는 방법은 이용율의 면에서 우수하였으며 아연원별에 의한 효과의 차이는 나타나지 않았다.

• 생태와환경
• /
• 제51권3호
• /
• pp.245-252
• /
• 2018

생물조절기법 (Biomanipulation)을 이용한 수질개선 방법으로서, 이매패류인 S. woodiana 종이 여과섭식을 통해 남조류(M. aeruginosa)를 효율적으로 제어할 수 있다는 것을 안정동위원소($^{13}C$, $^{15}N$) 추적자 실험을 통하여 밝혀내었다. 이매패류를 이용하여 호소수의 남조류 번성을 억제함으로서 호소 건강성을 회복시키는 것도 중요하지만, 외래종보다는 국내 자생종을 활용하는 것이 생태계 변화를 최소화 할 수 있다는 것을 고려해야 할 것이다.

• 한국농공학회논문집
• /
• 제50권1호
• /
• pp.25-37
• /
• 2008

When livestock facilities in Korea have been changed larger and denser, rearing conditions have been getting worse and the productivity of animal production have been decreased. Especially in the cold season, the minimized ventilation has generally been operated to save energy cost in Korea resulting in very poor environmental condition and high mortality. While the stability, suitability, and uniformity of the rearing condition are the most important for high productivity, the ventilation configuration is the most important to improve the rearing condition seasonally. But, it is so difficult to analyze the internal air flow and the environmental factors by conducting only field experiment because the weather condition is very unpredictable and unstable as well as the structural specification can not be easily changed by the researchers considering cost and labor. Accordingly, an aerodynamic computer simulation was adopted to this study to overcome the weakness of conducting field experiment and study the aerodynamic itself. It has been supposed that the airflow is the main mechanism of heat, mass, and momentum transfers. To make the simulation model accurately and actually, simplified pig models were also developed. The accuracy of the CFD simulation model was enhanced by 4.4 % of errors compared with the data collected from field experiments. In this paper, using the verified CFD model, the CFD computed internal rearing condition of the mechanically ventilated pig house were analyzed quantitatively as well as qualitatively. Later, this developed model will be computed time-dependently to effectively analyze the seasonal ventilation efficiency more practically and extensively with tracer gas decay theory.