• Nuclear Engineering and Technology
• /
• v.56 no.2
• /
• pp.575-600
• /
• 2024

During an earthquake on December 29th 2020, the Krško NPP automatically shutdown due to the trigger of the negative neutron flux rate signal on the power range nuclear instrumentation. From the time course of the detector signal, it can be concluded that the fluctuation in the detector signal may have been caused by the mechanical movement of the ex-core neutron detectors or the pressure vessel components rather than the actual change in reactor power. The objective of the analysis was to evaluate the sensitivity of the neutron flux at the ex-core detector position, if the detector is moved in the radial or axial direction. In addition, the effect of the core barrel movement and core inside the baffle movement in the radial direction were analysed. The analysis is complemented by the calculation of the thermal and total neutron flux gradient in radial, axial and azimuthal directions. The Monte Carlo particle transport code MCNP was used to study the changes in the response of the ex-core detector for the above-mentioned scenarios. Power and intermediate-range detectors were analysed separately, because they are designed differently, positioned at different locations, and have different response characteristics. It was found that the movement of the power range ex-core detector has a negligible effect on the value of the thermal neutron flux in the active part of the detector. However, the radial movement of the intermediate-range detector by 5 cm results in 7%-8% change in the thermal neutron flux in the active part of the intermediate-range detector. The analysis continued with an evaluation of the effects of moving the entire core barrel on the ex-core detector response. It was estimated that the 2 mm core barrel radial oscillation results in ~4% deviation in the power and intermediate-range detector signal. The movement of the reactor core inside baffle can contribute ~6% deviation in the ex-core neutron detector signal. The analysis showed that the mechanical movement of ex-core neutron detectors cannot explain the fluctuations in the ex-core detector signal. However, combined core barrel and reactor core inside baffle oscillations could be a probable reason for the observed fluctuations in the ex-core detector signal during an earthquake.

• Proceedings of the Korean Society for Technology of Plasticity Conference
• /
• 2004.05a
• /
• pp.87-90
• /
• 2004

In this paper, net-shape forming of an automobile gear is investigated. Barrel, a component of automobile start motor, is adopted as a net-shape forming. In order to accomplish the goal of net-shape forming without cutting of tooth and cam after forming, forming ability is raised through billet treatment and die design. As a technique of billet treatment spheroidizing annealing of billet to get low hardness and molybdenum disulphide coating to get low contact friction between billet and die is carried out. One of critical points of die design, fillet radii variation of tooth of die is applied to get smooth surface of barrel after cold forging. As a measurement of tooth accuracy, distance between two pins and lead-tooth alignments are investigated. Cam profile accuracy is checked with a 3D measuring instrument. Results obtained from the tests revealed reasonable result with respect to design goal. By these results, the paper shows that reasonable results can be obtained by billet treatment and die design for net-shape forming.

• Transactions of The Korea Fluid Power Systems Society
• /
• v.1 no.3
• /
• pp.7-13
• /
• 2004

The hydraulic pump for a Electro-hydrostatic Actuator for aircrafts should be able to quickly feed large volume of oil into hydraulic cylinder in order to reduce the response time. On the other hand, it should be also able to precisely dispense small amount of oil by low-speed operation so that the steady state position control error of the EHA can be accurately compensated. This paper is focused on the investigation how the plasma coating surface treatment of cylinder barrel with CrSiN can contribute to the reduction of low-speed friction torque of a bent-axis type piston pump. The results showed that the reduction of the friction torque was not remarkable, but that the anti-wear characteristics of the CrSiN-coated cylinder barrel were much better that those of the original one.

• Journal of Mechanical Science and Technology
• /
• v.20 no.3
• /
• pp.358-365
• /
• 2006

The hydraulic pump of an Electro-hydrostatic Actuator should be able to quickly feed large volume of oil into hydraulic cylinder in order to reduce the response time. On the other hand, it should be also able to precisely dispense small amount of oil through low-speed operation so that the steady state position control error of the actuator can be accurately compensated. Within the scope of axial piston type hydraulic pumps, this paper is focused on the investigation how the surface treatment of their cylinder barrel with TiN plasma coating can contribute to the reduction of the friction and wear rate of valve plate in the low-speed range with mixed lubrication. The results showed that the friction torque of the valve plate mated with a TiN coated cylinder barrel could be reduced to 22% of that with an uncoated original one when load pressure was 300 bar and rotational speed 100 rpm. It means that the torque efficiency of the test pump was expected to increase more than 1.3% under the same working condition. At the same time, the wear rate of the valve plate could be reduced to $40\sim50%$.

• Journal of Ginseng Research
• /
• v.37 no.2
• /
• pp.219-226
• /
• 2013

This study was conducted to investigate the effect of extrusion conditions (moisture content 20% and 30%, screw speed 200 and 250 rpm, barrel temperature $115^{\circ}C$ and $130^{\circ}C$) on the acidic polysaccharide, ginsenoside contents and antioxidant properties of extruded Korean red ginseng (KRG). Extruded KRGs showed relatively higher amounts of acidic polysaccharide (6.80% to 9.34%) than non-extruded KRG (4.34%). Increased barrel temperature and screw speed significantly increased the content of acidic polysaccharide. The major ginsenosides (Rb1, Rb2, Rc, Rd, Re, Rf, Rg2s, Rg3s, Rh1, and Rg3r) of KRG increased through extrusion, while the ginsenoside (Rg1) decreased. The EX8 (moisture 30%, screw speed 250 rpm, and temperature $130^{\circ}C$) had more total phenolics and had a better scavenging effect on 2,2-diphenyl-1-picrylhydrazyl radicals than those of extruded KRG samples. The extrusion cooking showed a significant increase (6.8% to 20.9%) in reducing power. Increased barrel temperature significantly increased the values of reducing power, the highest value was 1.152 obtained from EX4 (feed moisture 20%, screw speed 250 rpm, and temperature $130^{\circ}C$). These results suggest that extrusion conditions can be optimized to retain the health promoting compounds in KRG products.

• Journal of the Korean Society of Manufacturing Technology Engineers
• /
• v.18 no.6
• /
• pp.585-589
• /
• 2009

Extruder is divided to greatly three part at extrusion process. First, by hopper(Hopper) second, barrel(Barrel) with Screw that is point of extruder and third that is raw material supply wealth extrusion into dies(DIES) Part that decide shape of do product greatly divide. Hopper is role that distribute in raw material supply wealth (Feeding zone) of Screw preserving raw material in state of high quality how at extrusion process, and make distributed raw material as Screw in barrel rotates and 3 stage and inflicting heat and pressure raw material melting(Melting) state. And raw material of melting state Screw's measuring stoker(Metering zone) whereabouts anaphora do and product is completed through pipe channel of dies. Dies that is the most important as Screw in extrusion is part that is last part of melting state process of raw material and causes huge effect in quality of product. If more than design of dies happens, manufacture itself of dies is hard, but there are a lot of amount of losses accordingly. In this research, make pipe channel that raw material of melting state flows in dies can present dies basic design method through flow analysis of ideal pipe channel using CFdesign.

• The Research Journal of the Costume Culture
• /
• v.18 no.4
• /
• pp.599-611
• /
• 2010

The purpose of this study is to develop the most appropriate garment patterns for dog. This study is analyzed the body structures and bodily movements of different types of dogs and constructed garment patterns that are appropriate for each category: the basic pattern for dogs with oval-shaped chests; and the modified pattern for the ones with barrel-shaped chests. Analyzing some of the existing patterns in the market as well as studying the size chart of one of the dog apparel manufacturers, who participated in the Fashion Week for the very first time, were undertaken in order to understand the bodily figures and movements of dogs. Furthermore, based the previous studies and relevant information available regarding some of the most popular dogs in four selected countries: (names of the selected countries), dogs were broadly categorized into three groups according to the shape of their chests: Oval, Barrel, and Flat-sided. Later, two types of pattern were created and then constructed for fitting: the basic pattern for oval-shaped chest; and the modified pattern for barrel-shaped chest. As a result, the two patterns turned out to be most suitable for pet dogs.

• Steel and Composite Structures
• /
• v.14 no.6
• /
• pp.571-586
• /
• 2013

This paper focuses on the buckling capacity of a hybrid grid shell. The eigenvalue buckling, geometrical non-linear elastic buckling and elasto-plastic buckling analyses of the hybrid structure were carried out. Then the influences of the shape and scale of imperfections on the elasto-plastic buckling loads were discussed. Also, the effects of different structural parameters, such as the rise-to-span ratio, beam section, area and pre-stress of cables and boundary conditions, on the failure load were investigated. Based on the comparison between elastic and elasto-plastic buckling loads, the effect of material non-linearity on the stability of the hybrid barrel vault is found significant. Furthermore, the stability of a hybrid barrel vault is sensitive to the anti-symmetrical distribution of loads. It is also shown that the structures are highly imperfection sensitive which can greatly reduce their failure loads. The results also show that the support conditions pose significant effect on the elasto-plastic buckling load of a perfect hybrid structure.

• The Bulletin of The Korean Astronomical Society
• /
• v.45 no.1
• /
• pp.68.1-68.1
• /
• 2020

외계행성 대기 연구를 위한 투과스펙트럼 관측에 적합한 측분광기를 개발하고 있다. 이 측분광기의 광학적 특성은 380~685nm의 파장범위, FOV 10', R>~400이며, 슬릿부, collimator, VPH grism, imaging lens와 CCD로 구성되어 있는데, 보현산천문대 1.8m 망원경의 CIM(Cassegrain Interface Module)에 카트리지 방식으로 장착되어 사용한다. 그 중 doublet 렌즈 2개를 대칭으로 배치하여 초점거리 280mm가 되도록 만든 collimator는 슬릿을 통과한 f/8 입사광에서 지름 35 mm의 pupil을 만드는데, 이곳에 VPH grism을 설치하였다. collimator 렌즈는 axial spring과 radial spring으로 알루미늄 barrel에 고정하였다. 이 collimator barrel은 CIM에 쉽게 장탈착 할 수 있도록 모듈화 하였다. Collimator Barrel에 대한 구조 해석 결과, 망원경 이동에 따른 중력에 의한 변형은 충분히 작았다. Grism은 슬라이딩 형태로 장착되어 영상 확인도 가능하도록 설계하였다.

• Food Science and Preservation
• /
• v.12 no.3
• /
• pp.241-246
• /
• 2005

This study showed the optimum conditions for producing rice extrudate added with the sea tangle powder, and presented the effects of moisture content, barrel temperature and the amount of sea tangle powder. From the results, the more the amount of sea tangle powder was added, the less the water absorption ratio was showed, while the more the texture became smooth, the more the expansion ratio increased. From the sensory evaluation, the best preference was obtained when the moisture content was $18\%$, and the barrel temperature was at $100^{\circ}C$. Between control and $10\%$ sea tangle, there was no significant difference in all observed parameters. But if more than $20\%$ sea tangle was added, low sensory evaluation scores were obtained due to the peculiar smell from sea tangle. From these results, addition of sea tangle below $10\%$(w/w) did not affect the quality of products.