• Journal of the Korean institute of surface engineering
• /
• v.44 no.2
• /
• pp.60-67
• /
• 2011

Ternary B-C-N coatings were deposited on Si(100) wafer substrate from $B_4C$ target by RF magnetron sputtering technique in $Ar+N_2+CH_4$ gas mixture. In this work, the effect of reactant gas ratio, $CH_4/(N_2+CH_4)$ on the composition, kinds and amounts of bonding states comprising B-C-N coatings were investigated using two different bias power sources of continuous and unipolar DCs. In addition, the tribological properties of coatings were studied with the composition and bonding state of coating. It was found that the substrate bias power had an effect on chemical composition, and all of the obtained coatings were nearly amorphous. Main bonding states of coatings were revealed from FTIR analyses to be h-BN, C-C, C-N, and B-C. The amount of C-C bonging mainly increased with increase of the reactant gas ratio. From our studies, both C-C and h-BN bonding states improved the tribological properties but B-C one was found to be harmful on those. The best coating from tribological points of view was found to be $BC_{1.9}N_{2.3}$ composition.

• Journal of Veterinary Clinics
• /
• v.29 no.3
• /
• pp.213-219
• /
• 2012

The recombinant bovine somatotropin (rbST) has been used for increasing milk production of dairy cows without adverse health effects. This study was conducted to compare effects of supplementation with $Boostin^{(R)}$-250 containing 250 mg of rbST on milk production with those of $Posilac^{(R)}$ and $Boostin^{(R)}$-S. And safety of rbST supplementation on target animals was also observed. Each twenty-five lactating dairy cows were assigned randomly to one of four groups. $Boostin^{(R)}$-250 and vehicle (control) were administered weekly. $Boostin^{(R)}$-S and $Posilac^{(R)}$ were administered two week intervals. Milk yield, milk components, milk somatic cell count, health status, and body condition score of cows were examined. Supplementation with $Posilac^{(R)}$, $Boostin^{(R)}$-S, and $Boostin^{(R)}$-250 induced more milk yield than control group by 2.9 kg/day (12.3%), 4.2 kg/day (17.9%), and 4.1 kg/day (17.4%), respectively. There was a significant difference in milk yield among three rbST treatment groups and control group (${\alpha}$ = 0.05). The rbST supplementation did not increase the incidence of clinical mastitis and milk somatic cell counts. Supplementation with rbST did not significantly affect milk components (milk fat, protein, and solid not fat). The rbST supplementation of the dairy cows after peak milk yield did not cause negative effect on BCS. However, some cows less than 100 days in milking had decreased BCSs after rbST supplementation. In conclusion, milk production in 250 mg of rbST administered cows every week was similar to that of 500 mg of rbST administered cows every 2 weeks. And supplementation of 250 mg of rbST every week could reduce metabolic stress in cows.

• Korean Journal of Ecology and Environment
• /
• v.45 no.4
• /
• pp.356-367
• /
• 2012

Community structure of fish and inhabiting status of endangered species, Cobitis choii and Gobiobotia naktongensis were investigated in the Ji Stream, a tributary of the Geum River Drainage System of Korea from May to October 2011. Ten to 23 fish species inhabited upper stream (St. 1~St. 4) with a Aa-Bb river type composed of mostly pebble and cobble bottoms, 16~28 species did middle stream (St. 5~St. 7) with a Bb type composed of mostly cobble and boulder bottoms, and 20-29 species did lower stream (St. 8~St. 10) with a Bb-Bc type composed of mostly sand bottoms. A total of 44 species belonging to nine families were found in the stream during the survay. The dominant species were in the order of Zacco platypus (37.2%), Pungtungia herzi (5.8%) and Pseudogobio esocinus (5.5%). Other abundant species included Acheilognathus lanceolatus (5.3%), Zacco koreanus (5.2%), Hemibarbus longirostris (4.9%) and Squalidus gracilis majimae (3.5%). Among residing species, 16 species were endemic to Korea, two (Cobits choii and Gobiobotia naktongensis) were endangered, and one (Micropterus salmoides) was non-indigenous. The similarity index based on species composition and abundance clearly delineated the fish community of the Ji Stream according to the three major sections, which were defined at the above. Dominance index gradually decreased toward downstream, while diversity, evenness and species richness indexes gradually increased toward downstream. The two endangered species, C. choii and G. naktongensis co-occurred at the lower stream due to the prevalence of a sandy substratum.

• Fashion & Textile Research Journal
• /
• v.18 no.4
• /
• pp.424-437
• /
• 2016

The study will analyze the costumes of the Scythians tribes who lived in the region of Altai in the 3-5 century BC. The purpose of this study is to prepare new material to re-examine the theory, which claims that the origin of the circular motives of korean costumes are to be found in the typology of the Scythian costumes. In this study, we analyzed the most recent reports of archaeological excavation about the unearthed clothes in the Pazyryk region and compared its information with european literature. The conclusion of this study is as follows: The jackets of the Pazyryk region are classified in two types, (1) opened jacket with narrow sleeve and (2) enclosed jacket with narrow sleeve. Trousers were separated by (1) narrow and (2) extreme wide trousers. The enclosed jacket of tunic form and extreme wide trousers are newly excavated. It proves, there was a vivid exchange between the Scythians and their neighboring cultures. It can be noted, that there existed a diverse Scythian culture of costumes, besides the commonly known clothing culture of the "Pazyryk-rider". Based upon the results of the previous research, it can be said that the opened jacket with narrow sleeve and narrow trousers are costume typologies which are common for all Scythian tribes of the whole Eurasian region. The hem of the edge of jacket is proven to be a connective element, which is common to all Scythian tribes.

• Journal of the Korean Magnetics Society
• /
• v.22 no.4
• /
• pp.142-146
• /
• 2012

Records regarding to magnetism in the written Korean history were surveyed. In this article, we depicted how the magnetism (magnet) was understood by the public in the past in the Korea. The records about magnetism could be chronically categorized into three eras; 1) an era of recognizing a magnetic characteristics, 2) era of recognizing a magnetic pole, and 3) era of acquiring a modern knowledge. The written history of the Silla dynasty (BC57-AD935) revealed that a magnet was produced in this era. However, no record about magnet was found in the written history of the Goryo dynasty (918-1392). It was revealed that throughout the Korean history the interest in the magnetism (magnet) was emphasized most in the Josun dynasty (1392-1910). The magnetism (magnet) was most widely exploited in a geomancy. A magnetic compass was used widely to find a merciful direction and place in everyday life. In the era of Josun dynasty, a magnet was exploited as a magnetic compass for a navigation over the sea. An interesting usage of the magnet in the Josun dynasty was found in the pharmaceutical purpose.

• Resources Recycling
• /
• v.6 no.3
• /
• pp.28-35
• /
• 1997

Adsorption properities of hcavy metals (Cd, Cu, Fe, Mn, Pb, Zn) and organic compounds (Trichloroethylene and T Tetrachroethy len려 on sh$\xi$1I( oyster and ark shell) were investigated using wat$\xi$r treatment matenals, The shell powder (m띠or C crystal structurc is calcium hydroxide) showed the preference adsorption for heavy metals in order of Mn > Zn > Fe > Cd > eu > P Pb. The high removal capacities of heavy metals arc helicved to be largely due to precipitation by foonation of metal c carhonat,잃 and hydroxides at high pH caused by the $Ca(OH)_2$ component of sl1ell, immobilizatIon of heavy metals in a solid I matrix by calcium‘ and fixation by insoluble organic materials in the oystcr and ark shell. The use of sh려I in water treatment h has the potential to bc benefIcial as a source of inexpensive matcrials‘ moreover, not only treatment of waste but also e environmcntal business including environmental-purification ceramics could be better off by utili낌ng high-valued waste and d developed puri'fication ceramics and media.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.9 no.2
• /
• pp.262-267
• /
• 2005

During several method of improvement efficient, We analyzed Doherty Amplifier That used by simple circuit and 180w PEP LDMOS to analyze improvement of efficient and linearity. We for testing performance of Doherty Amplifier compared with Balanced Class AB, the experimental results show when Peaking Amp $V_gs.P$=1.53V, the efficiency is increased at Maximum 11.6$\%$. After finding optimum bias point of linearity improvement by manual tuning gate bias, when WCDMA 4FA $V_gs.P$=3.68V IMSR could be increased maximum 3.34dB. especially, when we match bias point of Peaking amp at 1.53V, we could get a excellent efficiency increase and have fUR under -3203c at output power 43dBm.

• JSTS:Journal of Semiconductor Technology and Science
• /
• v.16 no.3
• /
• pp.339-345
• /
• 2016

This paper presents a two-stage power amplifier MMIC using a $0.4{\mu}m$ GaN-HEMT process. The two-stage structure provides high gain and compact circuit size using an integrated inter-stage matching network. The size and loss of the inter-stage matching network can be reduced by including bond wires as part of the matching network. The two-stage power amplifier MMIC was fabricated with a chip size of $2.0{\times}1.9mm^2$ and was mounted on a $4{\times}4$ QFN carrier for evaluation. Using a downlink LTE signal with a PAPR of 6.5 dB and a channel bandwidth of 10 MHz for the 2.6 GHz band, the power amplifier MMIC exhibited a gain of 30 dB, a drain efficiency of 32%, and an ACLR of -31.4 dBc at an average output power of 36 dBm. Using two power amplifier MMICs for the carrier and peaking amplifiers, a Doherty power amplifier was designed and implemented. At a 6 dB back-off output power level of 39 dBm, a gain of 24.7 dB and a drain efficiency of 43.5% were achieved.

• Proceedings of the KIEE Conference
• /
• 2006.10a
• /
• pp.18-19
• /
• 2006

In this study, dielectric properties of the ${Mg_5}{B_4}{O_{15}}$ (B=Ta, Nb) cation-deficient perovskite ceramics and its oscillator application are investigated. The cation-deficient perovskite ceramics are prepared through the solid-state route. According to the XRD pattern, ${Mg_4}{Ta_2}{O_9}$ and $Mg{Ta_2}{O_6}$ phase existed in calcined and sintered ${Mg_5}{Ta_4}{O_15}$ powder. Also ${Mg_5}{Ta_4}{O_{15}}$ phase added with increasing sintering temperature. In the case of calcined and sintered ${Mg_5}{Nb_4}{O_{15}}$ powder, single phase of ${Mg_5}{Nb_4}{O_{15}}$ is appeared. In the case of the ${Mg_5}{Ta_4}{O_{15}}$ and ${Mg_5}{Nb_4}{O_{15}}$ ceramics sintered at $1450^{\circ}C$ for 5h, the dielectric constant, quality factor, and temperature coefficient of the resonant frequency (TCRF) were 8.2, 259,473 GHz, $-10.91ppm/^{\circ}C$ and 14, 37,350 GHz, $-52.3\;ppm/^{\circ}C$, respectively. Simulated DR with ${Mg_5}{Ta_4}{O_{15}}$ ceramics had the operating frequency of 10.99 GHz and S(2,1) of -29.795 dB. Size of manufactured oscillator was $56{\times}48{\times}34\;mm^3 and operated at 11.93 GHz. Power output and second harmonic of oscillator were +13.61 dBm and -23.81 dBc at 23.85 GHz, respectively.

• Journal of Veterinary Clinics
• /
• v.30 no.3
• /
• pp.178-185
• /
• 2013

This study evaluated the effects of milk yield on the postpartum health and reproductive performance of dairy cows. In total, data were collected from 1,060 cows on six dairy farms, including their milk production, body condition score (BCS), postpartum disorders, and reproductive performance. The lactation data were grouped based on the 305-day milk yield into control (< 10,000 kg, n = 445) and high milk yield (${\geq}$ 10,000 kg, n = 615) groups. The milk fat and protein, and BCS were lower during the first 5 months postpartum in the high milk yield group compared with the control group (p < 0.01). Ovarian cysts were more frequent (p < 0.0001) in the high milk yield group (28.6%) than in the control group (15.3%), whereas endometritis tended to be less frequent in the high milk yield group (29.6%) than in the control group (35.1%, p = 0.06). A higher proportion of cows tended to receive reproductive hormones (p = 0.06) in the high milk yield group (62.4%) than in the control group (56.6%). The probability of a pregnancy after first insemination tended to be lower (odds ratio = 0.78, p = 0.07) in the high milk yield group (30.2%) than in the control group (35.2%). Furthermore, the hazard of pregnancy by 210 days in milk was lower in the high milk yield group (hazard ratio = 0.84, p = 0.04) than in the control group, which resulted in a 20-day increase in the median interval to pregnancy. In conclusion, high milk yield was related to lower milk fat and protein, lower BCS, an increased incidence of ovarian cysts, and increased use of reproductive hormones, which resulted in decreased reproductive performance of dairy cows.