• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.54 no.6
• /
• pp.1036-1044
• /
• 2021

A linear array acoustic transducer with 12 tonpilz elements mounted independently on a gradual wedge-shaped tail mass was fabricated, tested and analyzed. The compensated transducer, which is modified by including a series inductance of 137 µH in the developed linear array transducer, attained improved figure of merit (FOM) performance characteristics compared with the uncompensated transducer. The four resonant frequency bands were identified from the measured FOM curve. The FOM response patterns over the frequency ranges of 31 to 40 kHz and 50 to 60 kHz were relatively uniform, whereas sharp resonance peaks were observed at around 73 kHz and 84 kHz. These results indicate that the developed linear array transducer can be used as an enhanced broadband transducer of echo sounder, and the operating frequency can be selected for more effective echo surveys in the fishing ground.

• Bulletin of the Korean Mathematical Society
• /
• v.34 no.4
• /
• pp.667-678
• /
• 1997

This paper contains a convergence analysis of a flexible restarted FOM(k)(FFOM(k)), and its performance is compared with FGMRES(k). Performances of these two algorithms with variable preconditioners are also compared with those of preconditioned FOM(k) and GMRES(k). Numerical experiments show that FFOM(k) performs as well as, or better than for some problems, FGMRES(k).

• Asian-Australasian Journal of Animal Sciences
• /
• v.17 no.6
• /
• pp.836-842
• /
• 2004

An experiment was conducted to study the performance of broilers chicks (2 to 42 d of age) fed diets containing pearl millet (PM, Pennisetum typhoides), foxtail millet (FOM, Setaria italica) or finger millet (FIM, Elusine coracana) totally replacing (w/w) yellow maize (YM) with and with out supplementing non-starch polysaccharide (NSP) hydrolysing enzymes at the rate of 0.5 g/kg diet. Enzyme preparation contained amylase 2,400 units, hemi-cellulase 5,400 units, cellulase 12,000 units, protease 2,400 units and beta-glucanase 106 units/g. Each diet was fed to eight replicates (five female Vencob broilers/replicate) housed in stainless steel battery brooders. The estimated metabolizable energy (ME) contents of YM, PM, FOM and FIM were FM (PM) were about 3,389, 2,736, 3,303 and 2,846 kcal/kg, respectively. Total replacement of YM with FOM did not influence the body weight gain, ready to cook yield, relative weights of giblet, liver, intestine, lymphoid organs (bursa and spleen) and length of intestine, antibody titers and livability at 42 d of age. But the food efficiency decreased significantly in FOM fed broilers compared those fed YM. Further, the fat content in thigh muscle reduced with FOM fed groups compared to those fed YM. The performance of broilers decreased significantly in PM and FIM fed broilers compared to those fed YM. The relative weights of giblet, gizzard and liver increased in FIM fed groups compared to those fed YM as the principal source of energy in broilers. Incorporation of NSP hydrolysing enzymes in commercial broiler diets improved the efficiency of feed utilization during starter phase but not at 42 d of age. The results thus indicate that yellow maize can be replaced in toto on weight basis in commercial broiler diets without affecting the performance. Supplementation of NSP hydrolysing enzymes was beneficial in enhancing feed utilization during the starter phase.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
• /
• v.9 no.3
• /
• pp.284-291
• /
• 1997

A hydrogen liquefaction equipment by direct cooling has been designed and built at KIST. Cool-down characteristics and liquefaction performance of the equipment have been investigated. The hydrogen liquefaction equipment consists of a GM refrigerator, a liquefaction velssel, a radiation shield and a cryostat. It is found that the hydrogen starts to be liquefied in the liquefaction vessel after 40~50 minutes of cool-down from the gas state of 270K. The effect of natural convection phenomena of charged gas in liquefaction vessel on the cool-down characteristics is evaluated by comparing with those in vacuum of liquefaction vessel. It is seen that the cool-down time of a liquefaction vessel is substantially increased in vacuum environment of liquefaction vessel. The experiments have been performed for 1~5 atm of hydrogen pressure to investigate the influence of hydrogen pressure on the liquefaction rate and figure of merit(FOM). It is found that both liquefaction rate and FOM are increased as the charged hydrogen pressure is increased.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.19 no.12
• /
• pp.498-506
• /
• 2018

Recently, the US commanded a wargame simulation system of a combined ROK-US exercise with single federation. However, after the OPCON transfer, many limitations to the single federation have been cited such as security policies and information protection. We suggest a hierarchical federation as a way to overcome these problems. Regarding HLA rules, the participants use the same FOM and RTI in single federation. There are limitations to implement CI in applying heterogeneous FOMs and RTIs in current single federation. Therefore, we propose implementing CI with heterogeneous FOMs and RTIs in a hierarchical federation. This system overcomes the weaknesses of the system structure, which is a disadvantage of the single federation. In the federation test, we can apply heterogeneous FOMs and RTIs and achieve similar performance to the current combined exercise simulation. In conclusion, ROK should lead the simulation system of combined exercises using the CI after the OPCON transfer.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
• /
• v.12 no.2
• /
• pp.131-139
• /
• 2000

A direct hydrogen liquefaction equipment has been developed and tested, which consists of a GM refrigerator, a liquefaction vessel, a radiation shield, a cryostat, and an ortho-para converter with catalyst. The effect of ortho-para hydrogen conversion on the performance of hydrogen liquefaction has been investigated. The time needed for the hydrogen liquefaction process with hydrogen pressure charge of 4 atm was delayed to around 75 minutes, and the liquefied mass flow rate of the hydrogen was about 0.0150∼ 0.0205 g/s when the hydrogen was liquefied with the direct hydrogen liquefaction system considering ortho-para conversion. With ortho-para conversion, the liquefied mass flow rate decreased up to 20%. Considering ortho-para conversion, there were up to 30% increase in the work input per unit liquefied mass flow rate. When the ortho-para conversion was considered, FOM decreased to be about 0.031∼0.045.

• Journal of Radiation Protection and Research
• /
• v.44 no.2
• /
• pp.53-63
• /
• 2019

Background: As neutron fields are always accompanied by gamma rays, it is essential to distinguish neutrons from gamma rays in the detection of neutrons. Neutrons and gamma rays can be separated by pulse shape discrimination (PSD) methods. Recently, we performed characterization of a stilbene scintillator detector and an EJ-301 liquid scintillator detector with a high-speed digitizer DT5730 and investigated optimized PSD variables for both detectors. This study is for providing a basis for developing fast neutron/gamma-ray dual-particle imager. Materials and Methods: We conducted PSD experiments using stilbene scintillator and EJ-301 liquid scintillator and evaluated neutron and gamma ray discriminability of each PSD method with a $^{137}Cs$ gamma source and a $^{252}Cf$ neutron source. We implemented digital signal processing techniques to apply two PSD methods - the charge comparison (CC) method and the constant time discrimination (CTD) method - to distinguish neutrons from gamma rays. We tried to find optimized PSD variables giving the best discriminability in a given experimental condition. Results and Discussion: For the stilbene scintillator detector, the charge comparison method and the constant time discrimination method both delivered the PSD FOM values of 1.7. For the EJ-301 liquid scintillator detector, both PSD methods delivered the PSD FOM values of 1.79. With the same PSD variables, PSD performance was excellent in $300{\pm}100keVee$, $500{\pm}100keVee$, and $700{\pm}100keVee$ energy regions. This result shows that we can achieve an effective discrimination of neutrons from gamma rays using these scintillator detector systems. Conclusion: We applied both PSD methods to a stilbene and a liquid scintillator and optimized the PSD performance represented by FOM values. We observed a good separation performance of both scintillators combined with a high-speed digitizer and digital PSD. These results will provide reference values for the dual-particle imager we are developing, which can image both fast neutrons and gamma rays simultaneously.

• International Journal of Air-Conditioning and Refrigeration
• /
• v.6
• /
• pp.124-135
• /
• 1998

A thermodynamic cycle analysis is performed for refrigerator-precooled Linde-Hampson hydrogen liquefiers, including catalysts for the ortho-to-para conversion. Three different configurations of the liquefying system, depending upon the method of the o-p conversion, are selected for the analysis. After some simplifying and justifiable assumptions are made, a general analysis program to predict the liquid yield and the figure of merit (FOM) is developed with incorporating the commercial computer code for the thermodynamic properties of hydrogen. The discussion is focused on the effect of the two primary design parameters - the precooling temperature and the high pressure of the cycle. When the precooling temperature is in a range between 45 and 60 K, the optimal high pressure for the maximal liquid yield is found to be about 100 to 140 bar, regardless of the ortho-to-para conversion. However, the FOM can be maximized at slightly lower high pressures, 75 to 130 bar. It is concluded that the good performance of the precooling refrigerator is significant in the liquefiers, because at low precooling temperatures high values of the liquid yield and the FOM can be achieved without compression of gas to a very high pressure.

• 전자공학회논문지 IE
• /
• v.44 no.2
• /
• pp.14-20
• /
• 2007

This paper presents quaternary D flip-flop with advanced performance. Quaternary D flip-flop is composed of the components such as thermometer code output circuit, EX-OR gate, bias inverter, transmission gate and binary D flip-flop circuit. The designed circuit is simulated by HSPICE in $0.35{\mu}m$ one-poly six-metal CMOS process parameters with a single +3.3V supply voltage. In the simulations, sampling frequencies is measured around 100MHz. The PDP parameters and FOM we estimated to be 59.3fJ, 33.7 respectively.

• Food Science of Animal Resources
• /
• v.39 no.2
• /
• pp.332-344
• /
• 2019

The objective of this study was to investigate slaughtering performance, carcass grade, and quantitative traits of cuts according to seasonal influence by each month in pigs slaughtered in livestock processing complex (LPC) slaughterhouse in Korea, 2017. A total of 267,990 LYD ($Landrace{\times}Yorkshire{\times}Duroc$) pig data were used in this study. Results of slaughter heads, sex distribution, carcass weight, backfat thickness, grading class, total weight, and fat and lean meat percentages of each cut predicted by AutoFom III were obtained each month. The number of slaughtered pigs was the highest in early and late fall but the lowest in midsummer. Only in midsummer that the number of females was higher than that of castrates. During 2017, carcass weight was the lowest in late summer. Backfat thickness was in the range of 21-22 mm. In mid and late spring, pigs showed high 1+ grade ratio (37.05% and 36.15%, respectively). For traits of 11 cuts predicted by AutoFom III, porkbelly showed lower total weight, lean weight, and fat weight in midsummer to early fall but higher lean meat percentage compared to other seasons. Weights of deboned neck, loin, and lean meat were the highest in midfall compared to other seasons (p<0.05). In conclusion, characteristics of slaughtering, grading, and economic traits of pigs seemed to be highly seasonal. They were influenced by seasons. Results of this study could be used as basic data to develop seasonal specified management ways to improve pork production.