• Journal of Powder Materials
• /
• v.5 no.1
• /
• pp.42-49
• /
• 1998

A study on the improvement of the impact energy in 93W heavy alloy with a Ni/Fe ratio of 9/1 has been carried out as a function of heat treatment temperature. The obtained results were compared to that of the traditional alloy system in which the Ni/Fe ratio is 7/3 or 8/2. With increasing heat treatment temperature from 1150 to 125$0^{\circ}C$, the impact energy of the alloy with the Ni/Fe ratio of 9/1 is remarkably increased from 42 to 72 J, which is higher than that of traditional alloy, up to 118$0^{\circ}C$ and then saturated. Fracture mode was also changed from brittle W/W boundary failure to W cleavage. The temperature showing the dramatic shrinkage by dilatometric anaysis of the heavy alloy with Ni/Fe ratio of 9/1 was found to be 1483 $^{\circ}C$, which is higher than that (146$0^{\circ}C$) of the heavy alloy with Ni/Fe ratio of 7/3. Auger Electron Spectroscopy showed that the segregation of impurities, such as S, P, and C in W/W grain boundary was considerably decreased with increasing heat treatment temperature from 1150 to l18$0^{\circ}C$. From the above results, it was found that the impurity segregation in W/W grain boundary played an important role on the decrease of impact properties, and the heat treatment temperature should be appropriately chosen, as considering the Ni/Fe ratio of the alloy, in order to get good impact properties.

• Geophysics and Geophysical Exploration
• /
• v.17 no.4
• /
• pp.202-208
• /
• 2014

KIGAM (Korea Institute of Geoscience and Mineral Resources) and MRAM (Mineral Resources Authority of Mongolia) performed joint survey on Bayan-Onjuul W-Mo mineralized area. Following the survey, we carried out magnetic survey. W-Mo occurrences are located with keeping a certain distance from the northern boundary of granite which has higher magnetic susceptibility values. Also, the 3D imaging results of magnetic inversion show that granite bodies are extended to the W-Mo occurrence areas from the deep main body with decreasing of susceptibility. The results of magnetic data analysis are well matched with the general characteristics of ore solution involved with W mineralization. The further study about the hidden ore deposits which have similar spatial relationship between granite and known WMo occurrences are necessary to improve the economic feasibility.

• Journal of the Korean Data and Information Science Society
• /
• v.22 no.4
• /
• pp.651-660
• /
• 2011

This study aims at improving teaching and learning abilities on the courses of probability/statistics in the fields of the S/W and H/W. In order to do this, this paper firstly conducts a survey which measures the perception of the surveyees' necessity of the related courses, and includes the contents that the related courses should cover. Secondly, this paper analyzes the educational effect on the achievement by studying Pattern Recognition, a major course of S/W and H/W, with combining probability/statistics or data analysis. Lastly, this paper suggests the promising pedagogical method for educating probability/statistics by using a survey and the case studies. In this way, this paper shows the necessity of probability/statistics for acquiring a new technology and the flexible approach of various subjects.

• Journal of the Korean Home Economics Association
• /
• v.34 no.4
• /
• pp.327-343
• /
• 1996

The objective of this study were 1) to determine the stages of concern of HE teachers about the practical problem-based curriculum approach, as illustrated by the Ohio's Work and Family Life Curriculum (W&FLC); 2) to determine the relationships between home economics (HE) teacher's stages of concern about W&FLC and personal and professional characteristics of HE teachers; and 3) to determine aspects of interest about the practical problem-based curriculum approach, such as the Ohio W&FLC. Respondents in this study were 225 HE teachers. The data were collected during the in-service teacher training sessions after presentation about W&FLC. Concerns Based Adoption Model (CBAM) was modified to provide a conceptual framework for this study. Frequencies, SD, mean, mode, range were used to determine the stages of concern of HE teachers. To determine the relationships between stages of concerns and personal and professional characteristics of HE teachers, coefficient of Chi-Square contingency tables was used. Content analysis was used to determine aspects of interest about the practical problem-bsed curriculum approach, such as W&FLC. The median of the stages of HE teachers' concerns about W&FLC was Stage 1, Information Stage. About 60% of HE teachers were interested in learning more details about W&FLC. Chi-square revealed no statistically significant relationships between stages of concerns about W&FLC and characteristics of HE teachers. Content analysis was used to determine aspects of interest about W&FLC of HE teachers. Nine categories were found: content, teaching strategies, implementation of the curriculum, philosophical framework, how to adopt W&FLC, resource materials, students' outcomes, in-service teacher training, and HE teacher organization. The majority of HE teachers were interested in relationships with family and others, resource management, family relationships, personal development, communication skill, family life, creating a self-identity, life planning, roles of family members, homemaking management, child care, and parenting.

• Plant Journal
• /
• v.14 no.3
• /
• pp.42-48
• /
• 2018

If the combined operation of Gwanggyo Cogeneration plant is similar to that of 2017, the CHP return temperature is lowered to $4^{\circ}C$, $6.3^{\circ}C$ and $7.8^{\circ}C$ according to the increase of heat surface area and the electric power is increased by 413 kW and 676 kW from its original 39,025 kW, and when the heat surface area is increased 75% electric power increases by 834 kW, totaling 39,859 kW. NPV, which is an economic analysis standard, is worth 350 million won, 500 million won, and 520 million won, and all measures to increase the heat surface area are proven to be worth the investment. As the heat transfer area increased, the electric power and NPV increased proportionally but the rise amount decreased. The electrical output and NPV were found to be the highest among the three options when the heat transfer area was increased by 75%.

• Food Science and Preservation
• /
• v.7 no.4
• /
• pp.373-379
• /
• 2000

The Ulmi corex extract was prepared using various solvents to investigate the availability as a natural antioxidant. The extracts were added to lard emulsion and the antioxidant activities were compared. The extract that had a greater antioxidant activity was fractionized. Then the antioxidant activity and substrate specificity of the fraction were examined and optimum concentration of addition was determined. To observe the antioxidative effect of the fraction in vivo, an inhibition rate of lipid peroxidation from which might be derived was measured using a microsome in rat's liver. Among the extracts of Ulmi cortex, the extract from water had the best antioxidant activity, and the addition of 0.05% (w/w) of ethyl acetate fraction showed similar antioxidant activity to a synthetic antioxidant, butylated hydroxyanisole(BHA). Ethyl acetate fraction (0.05%, w/w) also presented the antioxidative effect in lard, soybean oil, palm oil, and com oil. The inhibition of lipid peroxidation in liver microsome showed feater in the ethyl acetate fraction than caffeic acid in both nonenzymatic peroxidation (Fe$\^$++/ascorbate system) and enzymatic peroxidation (Fe$\^$++/-ADP/NaDPH system).

• Bulletin of the Korean Chemical Society
• /
• v.30 no.1
• /
• pp.107-113
• /
• 2009

This study investigated the decomposition activities of toluene on 10 mol% Al-W-incorporated mesoporous titano (15 mol %) silicates. The mesopore sizes observed in the transmission electron microscopy images ranged from 2.0 to 5.0 nm, and the pores were irregular on the addition of 10 mol% Al or W ions, but changed to regular hexagonal forms with the simultaneous additions of Al and W. The X-ray photon spectroscopy results showed a shift of the special peak for Ti2p in Al-incorporated mesoporous titanosilicates to a stronger binding energy compared to those of mesoporous titanosilicates and Al-incorporated mesoporous titanosilicates. Three O1s peaks in the spectra of the Al and W coexisted samples were observed at 530.5 and 531.7, 533, and 533.7eV, which were assigned to $Ti-Os\;in\;TiO_2\;and\;Ti_2O_3,\;Si-O\;in\;SiO_2\;and\;Al-O\;in\;Al_2O_3$, respectively. The toluene molecules desorbed at lower temperatures over W-incorporated mesoporous titanosilicates, and the amounts of toluene desorbed were also small; however, Al-incorporated mesoporous titanosilicates adsorbed much more toluene, particular over $Al_7.5-W_2.5-Ti_15-Si_75$. The photocatalytic decomposition of toluene was more enhanced over $Al_7.5-W_2.5-Ti_15-Si_75$ than over Al- or W-incorporated mesoporous titanosilicates only.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.9 no.1
• /
• pp.115-125
• /
• 1998

This paper examined the feasibility of adding a new NGSO/MSS(Non-Geostationary orbit/Mobile satellite service) service link to a frequency band which is already allocated to fixed-service microwave(M/W) system. To achieve this goal, the NGSO/MSS handset performance under the influence of the M/W multiple stations and the influence of handsets on the M/W station were both analyzed. Sharing criterions were also obtained by means of coordination contour in the former case, and handset capacity in the latter case. As the results, it was proven that sharing was feasible only when the vertical distance between handset and trendline was above 4 km except front and back points of M/W antenna bore sight under influence of 9 hops(the distance between hops = 50 km) M/W system on the NGSO/MSS handset, and only when the capacity of handset was below $7.0\times10^{-14}$ handsets/ $m^{2}$ under influence of handsets on the M/W station.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.29 no.2
• /
• pp.138-141
• /
• 2018

In this paper, we describe the designed digital waveform of a linear frequency-modulated (FM) chirp signal using field-programmable gate arrays (FPGAs) for image radar, and this signal is modulated with an I-Q modulator, and multiplied by 24 frequency multipliers to obtain a 94-GHz W-band wideband chirp generator. The developed chirp generator is an FM signal with a 94-GHz carrier frequency and a 960-MHz bandwidth, and the flatness is less than 1.0 dB at intermediate frequency (IF) (3.9 GHz), 2.0 dB in the W-band, and it has a 0.3-W output power in the W-band.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.18 no.11
• /
• pp.2697-2702
• /
• 2014

In this paper, we demonstrated a Ku-band 2W MMIC power amplifier for satellite communication applications. The device technology used relies on $0.25{\mu}m$ GaAs pseudomorphic high electron mobility transistor (PHEMT) of Wireless Information Networking (WIN) Semiconductor foundry. The 2W MMIC power amplifier has gain of over 29 dB and saturation output power of over 33.4 dBm in the frequency range of 13.75 ~ 14.5 GHz. Power added efficiency (PAE) is a 29 %. To our knowledge, this is the highest power added efficiency reported for any commercial GaAs-based 2W MMIC power amplifier in the Ku-band.