• Progress in Superconductivity and Cryogenics
• /
• v.16 no.4
• /
• pp.21-25
• /
• 2014

In order to develop 2nd generation (2G) high-temperature superconducting (HTS) wires as commercial products, it is necessary to perform a high speed investigation of their superconducting performance. Room-temperature and non-contact optical scanning tools are necessary to verify the microstructure of the superconducting materials, the current flow below the critical temperature, and the critical current density. In this paper, we report our results of an inspection of the electrical transport properties of coated conductors. The samples that we used in our study were highly qualified rare-earth based coated conductors produced via co-evaporation, and $SmBa_2Cu_3O_{7-y}$ (SmBCO) was the superconducting materials used in our studies. A film grown on IBAD-MgO templates shows larger than 400 A/cm at 77 K and a self-field. The local transport properties of the films were investigated by room-temperature imaging by thermal heating. The room-temperature images show structural inhomogeneities on the surface of the films. Bolometric response imaging via low-temperature bolometric microscopy was used to construct the local current mapping at the surface. These results indicate that the non-uniform regions on the surface disturb the current flow, and laser scanning images at room-temperature and at a low-temperature suggest a correlation between the structural properties and transport properties. Thus this method can be effective to evaluate the quality of the coated conductors.

• Publications of The Korean Astronomical Society
• /
• v.30 no.2
• /
• pp.133-137
• /
• 2015

The Galactic center uniquely provides opportunities to resolve how star clusters form in neutral gas overdensities engulfed in a large-scale accretion flow. We have performed sensitive Green Bank 100m Telescope (GBT), Karl G. Jansky Very Large Array (JVLA), and Submillimeter Array (SMA) mapping observations of molecular gas and thermal dust emission surrounding the Galaxy's supermassive black hole (SMBH) Sgr $A^{\ast}$. We resolved several molecular gas streams orbiting the center on ${\gtrsim}10$ pc scales. Some of these gas streams appear connected to the well-known 2-4 pc scale molecular circumnuclear disk (CND). The CND may be the tidally trapped inner part of the large-scale accretion flow, which incorporates inflow via exterior gas filaments/arms, and ultimately feeds gas toward Sgr $A^{\ast}$. Our high resolution GBT+JVLA $NH_3$ images and SMA+JCMT 0.86 mm dust continuum image consistently reveal abundant dense molecular clumps in this region. These gas clumps are characterized by ${\gtrsim}100$ times higher virial masses than the derived molecular gas masses based on 0.86 mm dust continuum emission. In addition, Class I $CH_3OH$ masers and some $H_2O$ masers are observed to be well associated with the dense clumps. We propose that the resolved gas clumps may be pressurized gas reservoirs for feeding the formation of 1-10 solar-mass stars. These sources may be the most promising candidates for ALMA to probe the process of high-mass star-formation in the Galactic center.

• Journal of Korea Water Resources Association
• /
• v.35 no.4 s.129
• /
• pp.411-423
• /
• 2002

Accurate and real time forecasting of runoff has a high priority in the drainage basins prone to short, high intensity rainfall events causing flash floods. To take into account the resolution of hydrological variables within a drainage basin, use of distributed system models is preferred. The Landsat Thematic Mapper(TM) observations enable detailed information on distribution of land cover and other related factors within a drainage basin and permit the use of distributed system models. This paper describes monitoring technique of rainfall excess by SCS curve number method. The time series maps of rainfall excess were generated for all the storm events to show the spatiotemporal distribution of rainfall excess within study basin. A combination of the time series maps of rainfall excess with a flow routing technique would simulate the flow hydrograph at the drainage basin outlet.

• Journal of Institute of Convergence Technology
• /
• v.2 no.1
• /
• pp.24-30
• /
• 2012

In this study, the trucks(2.9-liter) have been developed to use DME as fuel, and performance test of the vehicle's DME engine, power, emissions, fuel economy and vehicle aspects was conducted. For experiments, the fuel system(common-rail injectors and high-pressure pump included) and the engine control logic was developed, and ECU mapping was performed. As a result, the rail pressure from 40MPa to approximately 65% increase compared to the base injector has been confirmed that. Also, the pump discharge flow is 15.5 kg/h when the fuel rail pressure is 400rpm(40 MPa), and the pump discharge flow is 92.1 kg/h when the fuel rail pressure is 2,000rpm(40MPa). The maximum value of full-load torque capability is 25.5kgfm(based on 2,000rpm), and more than 90% compared to the level of the diesel engine were obtained. The DME vehicle was developed in this study, 120 km/h can drive to the stable, and calculated in accordance with the carbon-balance method of fuel consumptions is 5.7 km/L.

• Proceedings of the Korea Water Resources Association Conference
• /
• 2019.05a
• /
• pp.105-105
• /
• 2019

보나 여수로와 같은 수공구조물의 주변에서 발생하는 흐름 거동은 구조물 모서리에서 발생하는 흐름분리(flow separation)와 이에 따른 전단층(shear layer)과 재순환(recirculation) 흐름 영역의 발달 그리고 분리된 흐름의 재부착(reattachment)이 특징이다. 공학적으로 난류의 해석에 있어서 이러한 흐름 거동들을 정확하게 예측하는 것은 수공구조물 설계에 있어서 중요하다. 이 연구에서는 흐름 분리와 재순환 영역의 발달 그리고 흐름 재부착을 포함하는 후방계단(backward-facing step) 흐름을 155,000의 레이놀즈수 조건에서 하이브리드 RANS/LES 모델을 적용하여 해석결과를 평가한다. 하이브리드 모델로는 벽에 인접한 격자의 해상도에 상대적으로 민감하지 않은 SST(shear-stress transport) 난류 모델을 이용하는 DES(detached-eddy simulation) 기법을 적용하였다. 계단 높이가 h인 계산영역은 흐름방향 길이가 34h, 높이는 계단 상류와 하류에서 각각 1h와 2h 그리고 폭은 $2{\pi}$이다. 계단은 상류단으로부터 10h 하류부 지점에 위치한다. 경계조건으로 상부와 하부 벽면에 대해서는 비활조건을 적용한다. 상류부 수로에서 완전 발달한 흐름을 재현하기 위해서 유입경계조건은 유입부 하류 $2{\pi}h$ 지점에서 계산된 유속과 난류량을 매핑(mapping)기법을 이용하여 반복적으로 적용한다. 총 3.1백만개와 7.3백만개의 셀로 계산영역을 구현한 두 개의 계산격자 그리고 약 3.1백만개의 셀을 이용했지만 벽면 근처에서의 격자 구성을 다른 방식으로 설정한 두 가지 격자를 이용하여 격자 해상도가 DES 수치해석 결과에 미치는 영향을 분석하였다. 수치해석결과는 본 연구에서 상류단 조건으로 적용한 매핑기법이 대상 수로에서 완전 발달한 흐름을 잘 재현함을 보여주며, 합리적인 DES 해석 결과를 얻기 위해서는 벽에 수직한 방향으로 적절한 격자의 해상도와 분포가 필요함을 보여준다.

• Journal of The Geomorphological Association of Korea
• /
• v.26 no.3
• /
• pp.53-67
• /
• 2019

The purpose of this study is to identify the quality of landslide susceptibility in a landslide-prone area (Jinbu-myeon, Gangwon-do, South Korea) by spatial prediction modeling approach and compare the results obtained. For this goal, a landslide inventory map was prepared mainly based on past historical information and aerial photographs analysis (Daum Map, 2008), as well as some field observation. Altogether, 550 landslides were counted at the whole study area. Among them, 182 landslides are debris flow and each group of landslides was constructed in the inventory map separately. Then, the landslide inventory was randomly selected through Excel; 50% landslide was used for model analysis and the remaining 50% was used for validation purpose. Total 12 contributing factors, such as slope, aspect, curvature, topographic wetness index (TWI), elevation, forest type, forest timber diameter, forest crown density, geology, landuse, soil depth, and soil drainage were used in the analysis. Moreover, to find out the co-relation between landslide causative factors and incidents landslide, pixels were divided into several classes and frequency ratio for individual class was extracted. Eventually, six landslide susceptibility maps were constructed using the Bayesian Predictive Discriminant (BPD), Empirical Likelihood Ratio (ELR), and Linear Regression Method (LRM) models based on different category dada. Finally, in the cross validation process, landslide susceptibility map was plotted with a receiver operating characteristic (ROC) curve and calculated the area under the curve (AUC) and tried to extract success rate curve. The result showed that Bayesian, likelihood and linear models were of 85.52%, 85.23%, and 83.49% accuracy respectively for total data. Subsequently, in the category of debris flow landslide, results are little better compare with total data and its contained 86.33%, 85.53% and 84.17% accuracy. It means all three models were reasonable methods for landslide susceptibility analysis. The models have proved to produce reliable predictions for regional spatial planning or land-use planning.

• The Journal of Korean Medicine
• /
• v.27 no.2 s.66
• /
• pp.36-43
• /
• 2006

Objectives : Acupuncture has been widely applied to rehabilitation after stroke by Oriental medical doctors in Korea. It has been reported that acupuncture increased cerebral blood supply and stimulated the functional activity of brain nerve cells. In addition, a correlation between activation of specific areas of brain cortices and corresponding acupuncture stimulation at the therapeutic points had been well illustrated. rill now, however, there were few studies which evaluated a correlation between activation of specific areas of brain and frequently-used acupuncture therapy for stroke, such as LI4-LI11 electro-acupuncture (EA) for paresis after stroke. This study was undertaken to evaluate the effect of LI4-LI11 EA on regional cerebral blood flow (rCBF) in normal volunteers using Single Photon Emission Computed Tomography (SPECT). Methods : In the resting state, $^{99m}Tc-ECD$ brain SPECT scans were performed on 10 normal volunteers (8 males, 2 females, mean age $25.6{\pm}2.3$years; age range from 24 to 31 years). 7 days after the resting examination, 15 minutes of electro-acupuncture were applied at LI 4 and LI 11 on the right side of the subjects. Immediately after LI4-LI11 EA, the second SPECT images were obtained in the same manner as the resting state. Significant increases and decreases of regional cerebral blood flow after LI4-LI11 EA were estimated by comparing their SPECT images with those of the resting state using paired t statistics at every voxel, which were analyzed by Statistical parametric mapping with a threshold of p=0.001, uncorrected (extent threshold: k=100 voxels). Results : EA applied at right LI4-LI11 increased rCBF in right frontopolar area (Brodmann area 10) and left middle frontal area (Brodmann area 46). Interestingly, all the areas showing increased rCBF corresponded to the territories of both anterior cerebral arteries. However, LI4-11 EA decreased rCBF in the left occipital lobe (peristriate area, Brodmann area 19). Conclusions : The results demonstrated a correlation between LI4-11 EA and rCBF increase in the frontal lobes. It is also suggested that there may be a correlation between LI meridian and the territory of the anterior cerebral arterties.

• The Korean Journal of Nuclear Medicine
• /
• v.34 no.3
• /
• pp.183-198
• /
• 2000

Purpose: The purpose of this study was to evaluate alterations of regional cerebral blood flow (CBF) and cerebrovascular reserve (CVR), and correlation between these alternations and cognitive dysfunction in patients with chronic traumatic brain injury (TBI) and normal brain MRI findings. Materials and Methods: Thirty TBI patients and 19 healthy volunteers underwent rest/acetazolamide brain SPECT using Tc-99m HMPAO. Korean-Wechsler Adult Intelligence scale test was also performed in the patient group. Statistical analysis was performed with statistical parametric mapping software (SPM'97) Results: CBF was diminished in the left hemisphere including Wernicke's area in all patients with lower verbal scale scores. In addition, a reduction in CBF in the right frontal, temporal and parietal cortices was related with depressed scores in information, digital span, arithmetic and similarities. In patients with lower performance scale scores, CBF was mainly diminished in the right hemisphere including superior temporal and supramarginal gyri, premotor, primary somatomotor and a part of prefrontal cortices, left frontal lobe and supramarginal gyrus. CVR was diminished in sixty-four Brodmann's areas compared to control. A reduction in CVR was demonstrated bilaterally in the frontal and temporal lobes in patients with lower scores in both verbal and performance tests, and in addition, both inferior parietal and occipital lobes in information subset. Conclusion: Alterations of CBF and CVR were demonstrated in the symptomatic TBI patients with normal MRI finding. These alterations were correlated with the change of intelligence, of which the complex functions are subserved by multiple interconnected cortical structures.

• Composites Research
• /
• v.18 no.4
• /
• pp.35-43
• /
• 2005

In resin transfer molding(RTM), race-track effects and non-uniform fiber volume fraction may cause undesirable resin flow patterns and thus result in dry spots, which affect the mechanical properties of the finished parts. In this study, a real time RTM control strategy to reduce these unfavorable effects is proposed. This control rule is accomplished by means of the permeability mapping and pressure regulation. Through numerical simulations, the validity of the proposed scheme is demonstrated.

• Proceedings of the Korean Society for Emotion and Sensibility Conference
• /
• 2001.05a
• /
• pp.15-19
• /
• 2001

This paper describes effectiveness and characteristics of 3 P(point) task analysis as a new Ergonomic and Kansei design method for extracting user demand especially. The key point in 3 P task analysis is to describe the flow of tasks and extract any problems in each task. A solution of a problem means a user demand. 3 P task analysis cal eliminate an oversight of check items by examining the users' information processing level. The suers' information processing level was divided into the following three stages for problem extraction: acquirement of information ---> understanding and judgment ---> operation. Three stages has fourteenth cues such as difficulty of seeing, no emphasis, mapping for extracting problems. To link analysis results to the formulation of a product concept. I added a column on the right side of the table for writing the requirements (user demand) to resolve the problems extracted from each task. The requirements are extracted by using seventh cues. Finally 3 P task analysis was compared with group interview to make the characteristics of 3 P task analysis, especially extracting user demand, clear.