• Journal of Welding and Joining
• /
• v.12 no.2
• /
• pp.39-48
• /
• 1994

In comparison to the conventional brazing, laser welding of ceramics has advantages of direct bonding without filler material, which causes the thermal stress due to the differences of thermal expansion coefficients. In pulse-mode, laser welding of dispersion ceramic having high thermal resistance is possible at relatively low preheating temperature of $1300^{\circ}C$ In CW-mode, alumina can be welded at high preheating temperature $1500^{\circ}C$ under the condition of low feed rate of 500 mm/min, respectively. Further studies on developing mechanism of pores in the bead during laser welding of ceramics is required.

• Journal of IKEEE
• /
• v.17 no.1
• /
• pp.10-15
• /
• 2013

This paper, we analyzed that the measured data of the radiated power spectrum of electromagnetic waves of the normal spark ignition system and the spark ignition system with feed through type ceramic condenser. The results show that the strength of power spectrum radiated from the system with feed through type ceramic condenser is weaker than the normal system, and the density of power spectrum radiated from the system with feed through type ceramic condenser is smaller than the normal system. From these results, the feed through type ceramic condenser can reduce the electromagnetic waves radiating from the spark ignition system which is the spurious emission, and it can be concluded that the ignition coil of the spark ignition system generating high voltage pulse is equivalent to the radio frequency oscillator which is oscillating high frequency from a electronic point of view.

• Asian-Australasian Journal of Animal Sciences
• /
• v.20 no.7
• /
• pp.1039-1048
• /
• 2007

Two experiments were conducted to determine whether leptin is a metabolic signal for gonadotropin secretion in ewes. In the first experiment, twenty-eight cyclic Chal ewes were assigned randomly to an energy restricted, no leptin group (ERNL) (60% of maintenance; n = 14) and an energy normal, no leptin group (ENNL) (100% of maintenance; n = 14) for 71 days (6 estrous cycles). Estrus was synchronized with seven consecutive injections of $PGF_{2{\alpha}}$ Biweekly, body weight (BW) and body condition score (BCS) were determined and blood samples were collected to measure plasma leptin concentration. Blood samples were also taken to determine plasma progesterone concentration twice weekly. After each PG injection from the second injection to the end of experiment, four ewes were selected and blood samples were collected at 20 minutes and at hourly intervals for 3 h to detect plasma LH and FSH concentration. In the second experiment, after the ceasing of the estrous cycle caused by energy restriction, six acyclic ewes were selected and randomly allotted to two groups (n = 3) and received the following treatment for four days. Ewes in an energy restricted, leptin group (ERL) were fed with a ration which provided 60% of maintenance energy requirements and intravenously injected with $4{\mu}g$ leptin/kg BW daily. Ewes in an energy excess, no leptin group (EENL) were fed with a ration that provided 180% (120%+60%) of maintenance energy requirements and intravenously injected with 1 ml saline daily. In both groups, blood samples were collected at 20 minutes and at hourly intervals for 3 h before feeding on d 0 and d 5, and for 3 h before and after injections as above on d 2 and d 4 to detect plasma LH and FSH concentration. In the first experiment, BW and BCS from the $2^{nd}$ estrous cycle, and leptin from the $3^{rd}$ estrous cycle to the end of the experiment significantly (p<0.05) decreased. In ERNL ewes, mean plasma concentrations of FSH significantly (p<0.01) decreased from the $4^{th}$ estrous cycle to d 71 and LH pulsatile secretion was suppressed on d 71, so that, mean plasma concentrations of LH (p<0.05), LH pulse frequency (p<0.01) and LH pulse amplitude (p<0.05) significantly decreased. In the second experiment, injection of leptin significantly increased mean circulating concentrations of LH (p<0.05), LH pulse frequency (p<0.01), LH pulse amplitude (p<0.05) and mean circulating concentrations of FSH (p<0.01) and leptin (p<0.01). High energy intake significantly (p<0.05) stimulated pulsatile secretion of LH and leptin secretion (p<0.01), but non-significantly increased plasma FSH concentration. The results of this study indicate that leptin is a metabolic signal for the GnRH-LH/FSH axis in feed-restricted fat-tailed ewes.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.24 no.12B
• /
• pp.2382-2390
• /
• 1999

In this paper, we employed a new quantization scheme called sample-adaptive product quantizer (SAPQ) to quantize image data based on the differential pulse code modulation (DPCM) coder, which has fixed length outputs and high bit rates. In order to improve the performance of traditional DPCM coders, the scalar quantizer should be replaced by the vector quantizer (VQ). As the bit rate increases, it will be nearly impossible to implement a conventional VQ or modified VQ, such as the tree-structured VQ, even if the modified VQ can significantly reduce the encoding complexity. SAPQ has a form of the feed-forward adaptive scalar quantizer having a short adaptation period. However, since SAPQ is a structurally constrained VQ, SAPQ can achieve VQ-level performance with a low encoding complexity. Since SAPQ has a scalar quantizer structure, by using the traditional scalar value predictors, we can easily apply SAPQ to DPCM coders. For synthetic data and real images, by employing SAPQ as the quantizer part of DPCM coders, we obtained a 2~3 dB improvement over the DPCM coders, which are based on the Lloyd-Max scalar quantizers, for data rates above 4 b/point.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.66 no.7
• /
• pp.1066-1071
• /
• 2017

Recently high voltage impulse (HVI) technique has been extensively studied for desalting processes to control the $CaCO_3$ scale formation in industrial water practices such as power plant, boiler, and heat exchange operations. Investigation of the operational parameters for the HVI is important, however, those had not been reported yet. In this study, the effect of initial feed volume and contact time on reduction of calcium ion concentration by the HVI technique was investigated. Initial feed volumes of artificial hard water which contained 100 mg/L of $Ca^{2+}$, were set to 1, 2, and 3 L respectively. After 24hr of HVI contact with 12kV, $Ca^{2+}$ ion was reduced to 50, 29 and 19 % of their initial concentration, indicating that calcium removal increased as initial feed volume decreased. This implies the applied HVI pulse energy per unit mass of calcium is important parameter determining overall desalting efficiency. A series of extended operations of HVI up to 30 days verified the long term stability of the HVI system. The calcium ion declined to 40 mg/L after 2~3 days, and further reduction of calcium was not achieved, indicating that optimum operation time could be 2~3 days under these experimental conditions. Consequently, it was confirmed that the important operational parameter of HVI technique is initial feed volume and contact time as well as the applied voltage that was already proven in the previous study.

• Journal of Animal Reproduction and Biotechnology
• /
• v.36 no.1
• /
• pp.25-34
• /
• 2021

Kisspeptin is a key player in the central control of reproductive axis. Central administration of kisspeptin has been shown to advance puberty in rats. Stimulation of hypothalamic GnRH pulse generating mechanism by kisspeptin has been proposed to be the mechanism behind the onset of puberty. We hypothesized that chronic high doses of kisspeptin administration suppresses the reproductive axis and hence delays the pubertal onset. Hence, we investigated the effect of peripheral administration of chronic high doses of kisspeptin on pubertal onset, feed intake and body weight in female rats. Rats were treated with saline or kisspeptin (100 nmoles per day; intraperitoneal) for 26 days (day 25 to day 50 postnatal) and the day of vaginal opening was marked as day of puberty. Kisspeptin treated rats had delayed pubertal onset and reduced feed intake and body weight. Gonadal GPR54 mRNA was reduced suggesting that chronic high doses of kisspeptin may suppress the reproductive functions possibly by downregulation of GPR54 receptor. However, delay in puberty due to reduction in feed intake and body weight could not be ruled out in this study. Further, our study emphasizes the importance of dosage and duration of kisspeptin administration in the manipulation of reproductive axis. Our study, for the first time, suggests that kisspeptin and its analogues, if proven beneficial, could be used to treat precocious puberty in children. It appears that, though a promising tool for enhancing fertility, kisspeptin acts as a double-edged sword and has to be cautiously used to manipulate reproduction.

• Journal of the Korean Society for Precision Engineering
• /
• v.24 no.12
• /
• pp.50-56
• /
• 2007

Femtosecond laser ablation of the Invar alloy and hole drilling for a shadow mask are studied. We used a regenerative amplified Ti-sapphire laser with a 1kHz repetition rate, 184fs pulse duration and 785nm wavelength. Femtosecond laser pulse was irradiated on the Invar alloy with air blowing at the condition of various laser peak power. An ablation characteristic of the Invar alloy was appeared non-linear at $125J/cm^2$ of energy fluence. For the application to a shadow mask, the hole drilling of the Invar alloy with the cross section of a trapezoidal shape was investigated. The ablated micro-holes were characterized using an atomic force microscopy(AFM). The optimal condition of hole pattern f3r a shadow mask was $4\;{\mu}m$ z-axis feed rate, 0.2mm/s circular velocity, $26.4{\mu}J$ laser peak power. With the optimal processing condition, the fine circular hole shape without burr and thermal damage was achieved. Using the femtoseocond laser system, it demonstrates excellent tool for the Invar alloy micro-hole drilling without heat effects and poor edge.

• Korean Journal of Optics and Photonics
• /
• v.14 no.6
• /
• pp.583-587
• /
• 2003

In this paper, the optimal performance of optical second-order polarization mode dispersion (PMD) compensation has been investigated theoretically in terms of minimization of the root-mean-square (RMS) pulse broadening. The optimal compensation vector in feedforward-type second-order PMD compensation has been derived, and the RMS pulse broadening factor after the optimal second-order PMD compensation has been analytically calculated. The calculated result has been compared with the previously reported simulation result where numerically optimized feedback scheme was adopted. They are in good agreement, which verifies the validity of the derivation. The investigation in this work will form the basis for the implementation of the feed-forward-type second-order PMD compensation.

• Asian-Australasian Journal of Animal Sciences
• /
• v.17 no.1
• /
• pp.127-130
• /
• 2004

Lathyrus sativus, locally known as Khesari, is a leguminous pulse crop grown in many parts of the world for food (used by poor people) and animal feed/fodder. Its seeds are rich in protein and energy but contains anti-nutritional factors prominent among which is ${\beta}$-N-Oxalylamino-L-Alanine (BOAA), a neurotoxin causing lathyrism in humans due to prolong consumption. Keeping in view the chemical characteristics of this toxin and literary facts on L. sativus feeding in terrestrial animals, it was hypothesized that aquatic species may better utilise this ingredient in mixed extruded diets. Diets were prepared with varying levels (0, 10, 18, 26 and 34%) of L. sativus seeds and fed for 60 days to study growth, body composition and digestibility of nutrients. Final body weight, specific growth rate and feed and protein conversion ratio did not differ (p>0.05) between treatments. Crude protein digestibility was reduced (p<0.01) beyond 26% inclusion level of L. sativus. Final carcass composition with regard to protein, lipid and ash did not differ (p>0.05) among the treatments. Comparable craniosomatic, viscerosomatic, renosomatic and hepatic indices and no mortality implies no apparent adverse effect on the vital organs and fish health. It was concluded that L. sativus can be a promising feed ingredient that can be used up to 34% or possibly higher level in fingerlings diet. To our knowledge, it appears to be the first report of its kind under laboratory conditions.

• Asian-Australasian Journal of Animal Sciences
• /
• v.31 no.8
• /
• pp.1221-1229
• /
• 2018

Objective: A study was conducted to evaluate the varietal differences among faba bean straws and also to assess the potentials of faba bean straws supplemented with concentrate fed at the rate 70% straws and 30% concentrate mixture on feed intake, digestibility, body weight gain and carcass characteristics of the animals. Methods: Forty yearling Arsi-Bale sheep with initial body weight of $19.85{\pm}0.29kg$ (mean${\pm}$standard deviation) were grouped in a randomized complete block design into eight blocks of five animals each based on their initial body weight. Straws included in the study were from Mosisa (T1M), Walki (T2W), Degaga (T3D), Shallo (T4S), and local (T5L) varieties of faba bean and concentrate (2:1 ratio of wheat bran to "noug" seed cake). The experiment consisted of seven days of digestibility and 90 days of feeding trials followed by evaluation of carcass parameters at the end. Results: Local variety had lower (p<0.05) in grain and straw yield compared to improved varieties but higher in crude protein, metabolizable energy contents and in vitro organic matter digestibility. The apparent digestibility of dry matter and crude protein of sheep fed Walki and Mosisa straws were higher than (p<0.05) straws from Shallo varieties. Sheep fed Walki straw had greater (p<0.05) dry matter intake, average daily gain and feed conversion efficiency than sheep fed local and Shallo straws. Slaughter body weight and empty body weight were higher (p<0.05) for sheep fed Mosisa and Walki straws as compared to sheep fed Shallo straws. Apart from this, the other carcass components were not affected (p>0.05) by variety of the faba bean straws. Conclusion: There is significant varietal differences between faba bean straws both in quality and quantity. Similarly, significant variation was observed in feed intake, digestibility, body weight gain and feed conversion efficiency among sheep fed different straws of faba bean varieties with concentrate supplement. Based on these results, Walki and Mosisa varieties could be recommended as pulse crop rotation with cereals in the study area.