• KIEE International Transactions on Power Engineering
• /
• v.3A no.1
• /
• pp.1-6
• /
• 2003

As power systems grow more complex and power demands increase, the fault current tends to gradually increase. In the near future, the fault current will exceed a circuit breaker rating for some substations, which is an especially important issue in the Seoul metropolitan area because of its highly meshed configuration. Currently, the Korean power system is regulated by changing the 154 ㎸ system configuration from a loop connection to a radial system, by splitting the bus where load balance can be achieved, and by upgrading the circuit breaker rating. A development project applying 154 ㎸ Superconducting Fault Current Limiter(SFCL) to 154 ㎸ transmission systems is proceeding with implementation slated for after 2010. In this paper, the resistive and inductive SFCLs are applied to re-duce the fault current in Korean power system and their technical and economic impacts are evaluated. The results show that the application of SFCL can eliminate the need to upgrade the circuit breaker rat-ing and the economic potential of SFCL is evaluated positively.

• Journal of Information Processing Systems
• /
• v.11 no.1
• /
• pp.125-133
• /
• 2015

The Remote Device Management (RDM) protocol is used to manage the devices in the lighting control networks. RDM provides bi-directional communications between a controller and many lighting devices over the DMX512-A network. In RDM, using a simple binary search scheme, which is based on the 48-bit unique ID (UID) of each device, discovers the lighting devices. However, the existing binary search scheme tends to require a large delay in the device discovery process. In this paper, we propose a novel partition-based discovery scheme for fast device discovery in RDM. In the proposed scheme, all devices are divided into several partitions as per the device UID, and the controller performs device discovery for each partition by configuring a response timer that each device will use. From numerical simulations, we can see that there is an optimal number of partitions to minimize the device discovery time for a given number of devices in the proposed scheme, and also that the proposed partition-based scheme can reduce the device discovery time, as compared to the existing binary search scheme.

• KIEE International Transactions on Power Engineering
• /
• v.4A no.4
• /
• pp.221-226
• /
• 2004

As power systems grow more complex and power demands increase, the fault current tends to gradually increase. In the near future, the fault current will exceed a circuit breaker rating for some substations, which is an especially important issue in the Seoul metropolitan area because of its highly meshed configuration. Currently, the Korean power system is regulated by changing the 154kV system configuration from a loop connection to a radial system, by splitting the bus where load balance can be achieved, and by upgrading the circuit breaker rating. A development project applying a 154kV Superconducting Fault Current Limiter (SFCL) to 154kV transmission systems is proceeding with implementation slated for after 2010. In this paper, SFCL is applied to reduce the fault current in power systems according to two different application schemes and their technical and economic impacts are evaluated. The results indicate that both application schemes can regulate the fault current under the rating of circuit breaker, however, applying SFCL to the bus-tie location is much more appropriate from an economic view point.

• Nuclear Engineering and Technology
• /
• v.35 no.4
• /
• pp.299-308
• /
• 2003

Fabrication technique of $(Th,U)O_2$ pellets has been investigated. Powder mixtures of $ThO_2\;and\;UO_2$ were milled in two different ways-dry and wet milling. Milled powder was compacted and sintered to $(Th,U)O_2$ pellets. The wet-milled powder leads to a $(Th,U)O_2$ pellet having a high sintered density and uniform distribution of U and Th, compared to the dry-milled powder. The sintered density of a $(Th,U)O_2$ pellet tends to decrease by increasing the content of $ThO_2$. The thermal conductivity of $ThO_2\;and\;(Th,U)O_2$ pellets was measured by the laser flash method. The thermal conductivity of the $ThO_2$ pellet is higher than that of the $UO_2$ pellet, and the thermal conductivities of $(Th,U)O_2$ pellets containing $65wt\%\;and\;35wt\%\;ThO_2$ pellets are lower than that of the $UO_2$ pellet.

• Journal of Korean Society on Water Environment
• /
• v.27 no.6
• /
• pp.914-925
• /
• 2011

The variation of streamflow is regarded as one of the most influential factors on the fluctuation of water quality in the stream. The characteristics of the variation should be taken into account in the plans for the management of Total Maximum Daily Loads (TMDLs). This study analysed and characterized spatial distribution and temporal variation of streamflow at each unit watershed in Guem-river basin. For the analysis of the distribution of streamflow, the type and the extent of the distribution were investigated for the unit watershed. For the analysis of the variation, short and long term changes of streamflow were examined. The result showed that most of the distributions were not log-normalized and the extent of variation tends to be greater at the unit watershed placed on the tributaries in the basin. A kind of margin could be granted to the unit watershed involving high variations so as to establish the water quality goal and load allotment more reasonably and effectively in view of whole waterbody.

• Nuclear Engineering and Technology
• /
• v.54 no.7
• /
• pp.2386-2394
• /
• 2022

In this paper, smooth and notched bar tensile tests of austenitic stainless steel 304 are performed, covering four different multi-axial stress states and six different strain rate conditions, to investigate the effect of the stress triaxiality and strain rate on fracture strain. Test data show that the measured true fracture strain tends to decrease with increasing stress triaxiality and strain rate. The test data are then quantified using the Johnson-Cook (J-C) fracture strain model incorporating combined effects of the stress triaxiality and strain rate. The determined J-C model can predict true fracture strain overall conservatively with the difference less than 20%. The conservatism in the strain-based acceptance criteria in ASME B&PV Code, Section III, Appendix FF is also discussed.

• Korean Institute of Interior Design Journal
• /
• v.26 no.3
• /
• pp.63-70
• /
• 2017

The purpose of this study is to analyze the inner space of detached houses from 1980 to 2016. It was used 'space syntax program' for analysis and analyzed with intervals of 10 years as 1980~1990, 1990~2000 and so on. The research results will be summarized as follows: 1) Overall, all inner space that was examined shows a trend that integration space tends to increase while segregating space tends to decrease. 2) In the case of the master bedrooms(M B) in 1980s, these were composed of 2 rooms as a front room(F R) and a master bedroom type, but as time went by, the F R which was attached room to the M B disappeared. While inside space of M B attached powder-room and wardrobe instead of the F R of the M B. And F R was an integrated space at first in 1980s, but it began to change to a segregating space to protect personal privacy. 3) The dining(D) and kitchen(K) spaces were strictly separated in the 1980s but began to change to D+K and L+D+K types after 1990. 4) In the 2000s, the most typical living space in every house is continuing to change from an separate space in the other space to an integrated space where it is clearly seen from the kitchen and the dining room in the types as L+D and L+D+K.

• Journal of the Korean earth science society
• /
• v.35 no.4
• /
• pp.237-248
• /
• 2014

To analyze the characteristics of deposition and dispersion of volcanic ash emitted from Mt. Kirishima on January 26, 2011, several numerical simulations were carried out by using the numerical models including Weather and Research Forecast (WRF) and FLEXPART. The dispersion of ash located under 1 km high tends to be concentrated along the prevailing wind direction on January 26 2011. On the other hand, volcanic ash released on the following day spreads to Kirishima bay due to the intensified high pressure air mass in southern Kyushu. When Siberian air mass was intensified January 26, 2011, the deposition of volcanic ash is concentrated restrictedly in the narrow area along the wind direction of the downwind side of Mt. Kirishima. The development of high pressure air mass over the eruption area tends to induce the intensified horizontal diffusion of volcanic ash. Since the estimated deposition of volcanic ash is agreed well with observed values, the proposed numerical simulation is reasonable to use the assessment on the behavior of volcanic ash.

• Fashion & Textile Research Journal
• /
• v.11 no.4
• /
• pp.621-632
• /
• 2009

The purpose of this study was to analyze the physical characteristic of the wheelchair users by directly measuring the disabled men who use a wheelchair and to classify body types. The subjects were 178 male wheelchair users 20-69 years range of age. The results of this study were as follows. The cause of disability was classified into four groups; Poliomyelitis(P), Spinal Cord Injury(S), Cerebral Palsy(C), Amputee(A). There was a remarkable difference in the physical characteristic of the wheelchair users due to their cause of disability. A have greater values in all the dimensions. P have the largest drop values and smaller values in the lower body dimensions. S have greater values in the height of upper body trunk, back interscye length, and chest circumference, whereas smaller values in waist front length and thigh circumference. C have smaller values in most body dimensions except circumference of lower limb. By the factor analysis on the anthropometric data came out the result to be eight factors. The result of cluster analysis using factor scores shows the body types of wheelchair users can be divided into four body types; PY, RBB, TBP, RA. PY type is short and has the largest drop values, whereas RBB type tends to have the smallest drop values. TBP type is tall and the torso tends to be larger than those of the other types. RA type has smaller values in front body dimensions and moderate values in other dimensions. The diversity in body types should be considered among the wheelchair users.

• Nuclear Medicine and Molecular Imaging
• /
• v.42 no.sup1
• /
• pp.39-45
• /
• 2008

PET or PET/CT detects only less than 50% of early gastric cancer and 62-98% of advanced gastric cancer. Therefore, mass screening programs are recommended for all adults over the age of 40 for early detection and early treatment of gastric cancer through endoscopy or various radiological tests. The most important step after diagnosis of gastric cancer is accurate staging, which mainly evaluates tumor resectability to avoid unnecessary surgery. Important factors that affect tumor resectability are whether the tumor can be separated from adjacent organs or important blood vessels, the extent of lymph node metastasis, presence of peritoneal metastasis, or distant organ metastasis. To evaluate the extent of local tumor invasion, anatomical imaging that has superior spatial resolution is essential. There are a few studies on prognostic significance of FDG uptake with inconsistent results between them. In spite of lower sensitivity for lymph node staging, the specificity of CT and PET are very high, and the specificity for PET tends to be higher than that for CT. Limited data published so far show that PET seems less useful in the detection of lung and bone metastasis. In the evaluation of pleural or peritoneal metastasis, PET seems very specific but insensitive as well. When FOG uptake of primary tumor is low, distant metastasis also tends to show low FDG uptake reducing its detection on PET. There are only a few data available in the evaluation of recurrence detection and treatment response using FDG PET or PET/CT.