• Nuclear Engineering and Technology
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• 제41권5호
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• pp.729-738
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• 2009

Given the evolution of High-Temperature Gas-cooled Reactor(HTGR) designs, the source terms for licensing must be developed. There are three potential source terms: fission products, actinides in the fuel and tritium in the coolant. It is necessary to provide first an inventory of the source terms under normal operations. An analysis of source terms has yet to be performed for HTGRs. The previous code, which can estimate the inventory of the source terms for LWRs, cannot be used for HTGRs because the general data of a typical neutron cross-section and flux has not been developed. Thus, this paper uses a combination of the MCNP, ORIGEN, and MONTETEBURNS codes for an estimation of the source terms. A method in which the HTR-10 core is constructed using the unit lattice of a body-centered cubic is developed for core modeling. Based on this modeling method by MCNP, the generation of fission products, actinides and tritium with an increase in the burnup ratio is simulated. The model developed by MCNP appears feasible through a comparison with models developed in previous studies. Continuous fuel management is divided into five periods for the feeding and discharging of fuel pebbles. This discrete fuel management scheme is employed using the MONTEBURNS code. Finally, the work is investigated for 22 isotope fission products of nuclides, 22 actinides in the core, and tritium in the coolant. The activities are mainly distributed within the range of $10^{15}{\sim}10^{17}$ Bq in the equilibrium core of HTR-10. The results appear to be highly probable, and they would be informative when the spent fuel of HTGRs is taken into account. The tritium inventory in the primary coolant is also taken into account without a helium purification system. This article can lay a foundation for future work on analyses of source terms as a platform for safety assessment in HTGRs.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제8권2호
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• pp.483-503
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• 2014

In this paper, human action recognition using pyramid histograms of oriented gradients and collaborative multi-task learning is proposed. First, we accumulate global activities and construct motion history image (MHI) for both RGB and depth channels respectively to encode the dynamics of one action in different modalities, and then different action descriptors are extracted from depth and RGB MHI to represent global textual and structural characteristics of these actions. Specially, average value in hierarchical block, GIST and pyramid histograms of oriented gradients descriptors are employed to represent human motion. To demonstrate the superiority of the proposed method, we evaluate them by KNN, SVM with linear and RBF kernels, SRC and CRC models on DHA dataset, the well-known dataset for human action recognition. Large scale experimental results show our descriptors are robust, stable and efficient, and outperform the state-of-the-art methods. In addition, we investigate the performance of our descriptors further by combining these descriptors on DHA dataset, and observe that the performances of combined descriptors are much better than just using only sole descriptor. With multimodal features, we also propose a collaborative multi-task learning method for model learning and inference based on transfer learning theory. The main contributions lie in four aspects: 1) the proposed encoding the scheme can filter the stationary part of human body and reduce noise interference; 2) different kind of features and models are assessed, and the neighbor gradients information and pyramid layers are very helpful for representing these actions; 3) The proposed model can fuse the features from different modalities regardless of the sensor types, the ranges of the value, and the dimensions of different features; 4) The latent common knowledge among different modalities can be discovered by transfer learning to boost the performance.

• 대한인간공학회지
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• 제24권3호
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• pp.11-27
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• 2005

The objectives of this study are to analyze representative wrist postures while using hand tools and parts at general assembly processes, to evaluate perceived discomfort on the wrist when external loads are present, and to suggest an evaluation and prediction model of perceived discomfort. Sixteen subjects participated in an experiment to appraise perceived discomfort. Three types of the wrist postures with five levels of non-neutralities were analyzed when five levels of external load were applied to each posture. The ANOVA results showed that the perceived discomfort of wrist postures was significantly affected by both the wrist posture and external load (p$<$0.001). It was also shown that some of the interactions between external loads and the wrist postures(Flexion/$Extension^*$Load, Flexion/$Extension^*$supination/pronation, ulnar/radial $deviation^*$supination/pronation) were significant(p$<$0.001). The result implies that a new posture classification scheme for workload assessment methods may be needed to reflect such effects of external load and wrist posture. A regression model of perceived discomfort was developed with respect to wrist posture and external load from the experimental data. A subsequent experiment revealed that the correlation coefficient between the predicted values of perceived discomfort from the model and the actual values obtained from the experiment was about 0.98. It is expected that the results help to properly estimate the body stress resulting from worker's postures and external loads and can be used as a valuable design guideline to analyze potential hazard of musculoskeletal diseases in industry.

• 한국자동차공학회논문집
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• 제10권3호
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• pp.192-200
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• 2002

Semi-active suspension systems are greatly expected to be in the mainstream of future controlled suspensions for passenger cars. In this study, a continuous variable damper for a passenger car suspension is developed, which is controlled actively and exhibits high performance with light weight, low cost, and low energy consumption. To get fast response of the damper, reverse damping mechanism is adapted, and to get small pressure change rate after blow-off, a pilot controlled proportional valve is designed and analyzed. The reverse continuous variable damper is designed as a HS-SH damper that offers good body control with reduced transferred input force from tire, compared with any other type of suspension system. The damper structure is designed, so that rebound and compression damping force can be tuned independently, of which variable valve is placed externally. The rate of pressure change with respect to the flow rate after blow-off becomes smooth when the fixed orifice size increases, which means that the blow-off slope is controllable using the fixed orifice size. The damping force variance is wide and continuous, and is controlled by the spool opening, of which scheme is usually adapted in proportional valves. The reverse continuous variable damper developed in this study is expected to be utilized in the semi-active suspension systems in passenger cars after its performance and simplicity of the design is confirmed through real car test.

• 대한물리의학회지
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• 제11권3호
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• pp.65-72
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• 2016

PURPOSE: The purpose of this study is to determine the differences between the muscle activity of cranio-cervical flexion and extension muscles according to the types of tools used through a short-term intervention of cranio-cervical static stabilization exercises using small tools. METHODS: A total of fifteen male and female adults in their 20s who showed forward head posture in the overall body posture measurement system participated in this study. Each subject performed cranio-cervical static stabilization exercises about flexion and extension while using a sling, a foam roller, a TOGU ball, and without tools separately, and the muscle activity of the sternocleidomastoid muscle, scalenus anterior and splenius capitis was measured. Each value was measured for 10 seconds a total of three times. The maximum voluntary isometric contraction value was computed using the average during the middle four seconds. RESULTS: Cranio-cervical flexion exercises using various tool types, the average activity of the sternocleidomastoid and scalenus anterior muscles was significantly higher when applying the TOGU ball (p<.05). According to the results of implementing cranio-cervical flexion exercise using various tools, the maximum muscle activity of the sternocleidomastoid muscle was significantly higher for the TOGU ball (p<.05). CONCLUSION: Based on these results, the provision of an unstable surface using small tools rather than a stable surface is recommended as an exercise scheme for proprioceptive stimulation in a forward head posture. Particularly, we recommend using the TOGU ball for the provision of an unstable surface to increase the muscle activity of the sternocleidomastoid muscle and scalenus anterior.

• 대한기계학회논문집A
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• 제40권2호
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• pp.133-138
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• 2016

기존에는 로봇 말단에 6축 힘/토크 센서를 부착하여 로봇의 힘제어 및 충돌감지를 수행하였지만, 이 방법은 매우 고가이고, 로봇의 몸체에서 발생한 충돌을 감지할 수 없었다. 이의 대안으로 각 관절에 관절 토크센서를 장착하였으나, 토크 측정 시에 발생하는 다양한 오차로 인하여 실제 적용에 한계가 있었다. 이러한 문제를 해결하고자 본 연구에서는 정확한 토크 측정을 위한 관절 토크센서 및 이를 포함하는 관절모듈을 개발하였다. 제안된 관절모듈은 로봇에 인가되는 모멘트 부하를 지지하고, 조립 시 발생하는 응력을 감소시키기 위하여 토크센서에 디스크형 커플링을 첨가하여 원하는 회전토크만을 효과적으로 측정할 수 있도록 하였다. 본 논문에서는 다양한 실험을 통하여 제안한 토크센서의 성능을 검증하였다.

• Asian-Australasian Journal of Animal Sciences
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• 제27권9호
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• pp.1368-1372
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• 2014

Several studies arduously reported that gayal (Bos frontalis) is an independent bovine species. The population size is shrinking across its distribution. In Bangladesh, it is the only wild relative of domestic cattle and also a less cared animal. Their body size is much bigger than Bangladeshi native cattle and has prominent beef type characters along with the ability to adjust in any adverse environmental conditions. Human interactions and manipulation of biodiversity is affecting the habitats of gayals in recent decades. Besides, the only artificial reproduction center for gayals, Bangladesh Livestock Research Institute (BLRI), has few animals and could not carry out its long term conservation scheme due to a lack of an objective based scientific mission as well as financial support. This indicates that the current population is much more susceptible to stochastic events which might be natural catastrophes, environmental changes or mutations. Further reduction of the population size will sharply reduce genetic diversity. In our recent investigation with 80K indicine single nucleotide polymorphism chip, the $F_{IS}$ (within-population inbreeding) value was reported as $0.061{\pm}0.229$ and the observed ($0.153{\pm}0.139$) and expected ($0.148{\pm}0.143$) heterozygosities indicated a highly inbred and less diverse gayal population in Bangladesh. Prompt action is needed to tape the genetic information of this semi-domesticated bovine species with considerable sample size and try to investigate its potentials together with native zebu cattle for understanding the large phenotypic variations, improvement and conservation of this valuable creature.

• 한국항해항만학회:학술대회논문집
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• 한국항해항만학회 2005년도 춘계학술대회 논문집
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• pp.399-404
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• 2005

본 논문은 생체시스템의 인공면역시스템을 이용한 Immunized PID 제어기를 구성하였으며, 상층부위에 제동시스템이 부착된 다층 건축물의 진동제어에 적용하였다. 인공면역시스템은 인체가 외부로부터 침투하는 바이러스, 병원균 등으로부터 보호하기 위하여 내부의 항체들이 이를 극복하기 위하여 행동하는 현상을 모델링한 것으로써 외란입력에 대한 적응성 및 강인한 응답특성을 가지고 있다. 본 논문에서 설계된 제어시스템은 항만의 건축물에 능동제어기로 적용하였으며, 바람이나 지진과 같은 환경적 부하로 인해 발생되는 건축물의 응답변위를 컴퓨터 시뮬레이션을 통해 나타내었다. 그리고, 기존의 진동제어에 널리 이용되는 제어기도 함께 적용하여 제안한 제어기 성능의 우수성을 입증하고자 함과 동시에 인공면역시스템을 응용한 제어기 설계에 대한 비젼도 제시하고자 한다.

• 대한전자공학회논문지SD
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• 제48권4호
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• pp.24-31
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• 2011

본 논문은 Medical Implant Communications Service (MICS) 주파수 대역을 사용해서 SD급 동영상의 실시간 전송이 가능한 체내이식용 의료기기를 위한 고속 전송기법을 제안한다. 제안 기법은 채널당 300 kHz에 불과한 좁은 대역폭으로 인한 전송률의 제한을 극복하기 위해서 직교 주파수 분할 다중화(orthogonal frequency division multiplexing, OFDM) 기법에 기반을 둔 다중반송파 전송방식을 사용하여 다채널 전송이 가능하게끔 한다. 여러 개의 MICS 채널을 동시에 활용하는 송신신호의 파워스펙트럼이 MICS 대역의 주파수 활용 조건을 만족시키면서 스펙트럼 효율을 최대화할 수 있도록, 최적화된 부반송파 할당과 IFFT 사이즈, 그리고 사이드로브 억압 기술이 사용된다. 또한 제안하는 기법의 효율적인 구현을 위한 하드웨어 구조도 제시한다. 실험 결과, 본 논문의 기법을 적용한 시스템은 기존의 MICS 대역 트랜시버들보다 최대 약 10배의 전송률 (4.86 Mbps)을 지원할 수 있는 것으로 나타났다.

• 전자공학회논문지 IE
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• 제47권4호
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• pp.1-9
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• 2010

초음파신호를 이용하여 두 물체 사이의 거리를 측정할 수 있도록 초음파신호를 발생시키고 이를 수신하여 증폭하는 프론트-앤드 IC를 설계하였다. 40[kHz]~300[kHz]의 초음파 신호를 발생시켜서 피에조진동자를 통해 간헐적으로 송신하는 회로와 피에조 수신기에서 받은 미세한 반사 신호를 증폭하여 노이즈를 제거한 후 처음 송신된 신호와의 시간 차이를 펄스폭으로 출력하고 이를 이용하여 물체사이의 거리를 계산할 수 있는 기능을 내장하였다. 본 설계에서는 두 가지 기술을 작용하여 기능을 개선하였다. 첫째, 주파수 자동조정(SFC) 회로이다. OTA회로의 gm을 가변시켜 초음파 신호발생기의 출력주파수와 수신단의 밴드패스필터의 중심주파수가 서로 연동되도록 조정해 줌으로써 신호 복원을 용이하게 하였다. 둘째, 가변 이득 조절회로(VGC)이다. 이 회로는 두 물체사이의 거리에 상관없이 수신되는 신호의 진폭이 일정하도록 동작하는 기능을 한다. 또한, 출력레벨변환회로를 적용하여 송신신호의 진폭을 40[V]로 상승시켜 측정거리를 늘리는 시도를 하였다. 시뮬레이션을 위한 공정은 0.6um] 급, 40[V] CMOS 공정을 사용하였다. 전원전압 5[V], 소비전력은 약 12[mW]정도이다. 회로의 규모가 최소화 되어 있고 외부소자 수를 줄였기 때문에 휴대형기기에 편리하게 사용할 수 있게 하였다.