• Journal of Animal Science and Technology
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• v.50 no.5
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• pp.695-704
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• 2008

This study was conducted to investigate effects of dietary crude protein(CP) level and supplementation of conjugated linoleic acid(CLA) on growth performances and meat quality parameters in finishing pigs. The experiment was designed using protein levels(11.3%, 16.0%) and CLA levels(0%, 2.5%) according to 2×2 factorial design. A total of forty-eight pigs [(Landrace×Yorkshire)×Duroc] with an average initial weight of 79±1kg were allotted to one of four dietary treatments. Each treatment had four replications of three pigs per replicate. Final body weight(P<0.05) and average daily gain(P<0.01) were lower in 11.3% CP treatments than in 16.0% CP treatments, while feed/gain was high(P<0.01) in 11.3% CP treatments compared with 16.0% CP treatments. Carcass weight was lighter in 11.3% CP treatments(P<0.001) and CLA 2.5% treatments(P<0.01) than in 16.0% CP and CLA 0% treatments, respectively. A significant interaction between CP and CLA on carcass weight was observed(P<0.01), where supplementation of 2.5% CLA to finishing diets decreased carcass weight in 16.0% CP treatments, while no difference was found in 11.3% CP treatments. Backfat thickness was thinner in 11.3% CP treatments and CLA 2.5% treatments than in 16.0% CP and CLA 0% treatments, respectively(P<0.05). A significant interaction between CP and CLA on backfat thickness was observed(P<0.001), where supplementation of 2.5% CLA to finishing diets decreased backfat thickness in 16.0% CP treatments, while no difference was found in 11.3% CP treatments. Marbling score and intramuscular fat contents were higher in 11.3% CP treatments than in 16.0% CP treatments(P<0.01). In conclusion, feeding of protein-deficient diets in finishing pigs could produce favorable pork with high marbling score and thinner backfat. On the other hand, supplementation of CLA was considered to decrease backfat thickness when diets with optimal level of crude protein were fed to finishing pigs.

• Korean Journal of Microbiology
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• v.54 no.4
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• pp.384-397
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• 2018

The aim of this study is to screen the strains of Bacillus spp. possessing safety, probiotic activity, and so on, which can be utilized as probiotic resource for using the feed and supplement food of companion animal. About 300 isolates were isolated from traditional Korean sauces, four isolates that did not have or produce the six kinds of B. cereus type vomiting and diarrhea toxin genes, ${\beta}$-hemolytic, and three kinds of carcinogenic enzymes were selected. Antibiotic gene retention, cell surface hydrophobicity, antibiotic sensitivity, and glucose utilization were analyzed for four isolates, and finally SRCM 100731 was selected. SRCM 100731 was named as Bacillus amyloliquefaciens SRCM 100731 16S rRNA sequencing analysis, and carried out optimization of cell growth for industrial applications such as pet food and feed. The effects of 14 different components on cell growth were investigated and three significant positive factors, molasses, sodium chloride, and potassium chloride were selected as the main factors based on a Plackett-Burman design. In order to find out optimal concentration on each constituent, we carried out central composite design. The predicted optimized concentrations were 7% molasses, 1.1% sodium chloride, 0.5% potassium chloride. Finally, an overall about 7-fold increase in dry cell weight yield ($12.6625{\pm}0.0658g/L$) was achieved using the optimized medium compared with the non-optimized medium ($1.8273{\pm}0.0214g/L$). This research is expected to be highly utilized in the growing pet industry by establishing optimal cultivation conditions for industrial application as well as screening Bacillus amyloliquefaciens SRCM 100731 as probiotic resource for companion animal.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.7
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• pp.270-276
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• 2020

3D printing is an additive manufacturing technology that can produce complex shapes in a single process for a range of materials, such as polymers, ceramics, and metals. Recent 3D printing technology has developed to a level that enables the mass-production through an improvement of the printing speed and the continuous development of applicable materials. In this study, 3D printing technology using a laser was applied to manufacture a heat exchanger for an air compressor in a railway vehicle. First, the optimal design of the heat exchanger was carried out by focusing on weight reduction and compactness as a shape suitable for 3D printing. Based on the design derived, heat exchanger prototypes were made of AlSi10Mg alloy material by applying the SLM technique. Moreover, the manufactured prototypes were attached to an existing air compressor, and the heat exchange performance of the compressed air was tested. The test results of the 3D printed prototypes showed a heat exchange performance of approximately 80% and 85% at low and high-pressure, respectively, compared to the existing heat exchanger. From the 𝓔-NTU method results with an external cooling air condition similar to that of the existing heat exchanger, the calculated heat transfer amount of 3D printed parts showed similar performance compared to the existing heat exchanger. As a result, the 3D printed heat exchanger is lightweight with good performance.

• Resources Recycling
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• v.24 no.5
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• pp.15-21
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• 2015

Waste plastic differs in its speed of combustion owing to its variety in composition as well as kinds of plastic. This study is aimed at examining the thermal weight analysis and determination of its kinetics in order to derive the design element in pyrolysis of RPF (Refused Plastic Fuel) as the plastic solid fuel. Based on the result of TGA (Thermogravimetric analysis), kinetic characteristics were analyzed by using Kissinger method which are the most common method for obtaining activation energy, and experimental conditions of TGA were set as follows: in a nitrogen atmosphere, gas flow rate of 20 ml/min, heating rate of $5{\sim}50^{\circ}C/min$, and maximum hottest temperature of $800^{\circ}C$. The method used for determining the property of waste plastic when thermally decomposed was thought feasible as the basic data in deciding the performance, design, and optimal operating condition of the reactor in the actual reactor.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.19 no.2 s.72
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• pp.195-202
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• 2006

Thin-walled structures are efficiently utilized an automobiles, aircraft, satellite and ship as well as needed light weight simultaneously. This paper presents new shape of automobile hood reinforcement that rotating parts as engine, transmission are protected by thin-walled structures. The automobile hood is concerned about the resonance occurs due to the frequency of the rotating parts. The hood must be designed by supporting the stiffness of design loads and considering the natural frequencies. Hence, it is sustained the stiffness and considered the vibration by resonance. It is deep related to ride. Therefore, the topology, shape and size optimization methods are used to design the automobile hood. Topology technique is applied to determine the layout of a structural component optimum size with maximized natural frequency by volume reduction. In this research, The optimal structure layout of an inner reinforcement of an automobile hood for the natural frequency of a designated mode is obtained by using topology optimization method. The optimum size and the optimum shape are determined by PLBA(Pshenichny-Lim-Belegundu-Arora) algorithm.

• Asian-Australasian Journal of Animal Sciences
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• v.16 no.12
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• pp.1763-1769
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• 2003

Two experiments were conducted to examine the production and quality of cassava hay and its utilization in diets for dairy cows. In experiment I, a $2{\times}2$ Factorial arrangement in a randomized complete block design with 4 replications was carried out to determine the effects of different initial (IC) and subsequent cutting (SC) on yield and composition of cassava plant. The results revealed that cassava could produce from 4 to 7 tonne of DM and 1.2 to 1.6 tonne of CP for the first six months after planting. CP content in cassava plant ranged from 20.8 to 28.5% and was affected by different SC regimes. Condensed tannin in cassava foliage ranged from 4.9 to 5.5%. Initial cutting at 2 months with subsequent cutting at 2 month intervals was the optimal to obtain high dry matter and protein yield. In the second experiment, five crossbred Holstein-Friesian cows in mid lactation with an initial live-weight of 505${\pm}6.1kg$ and average milk yield of 10.78${\pm}1.2kg/d$ were randomly assigned in a $5{\times}5$ Latin square design to study the effects of 2 levels of CH (1 and 2 kg/hd/d) and concentrate (1 to 2 kg of milk and 1 to 3 kg of milk) on milk yield and milk composition. The results showed that cassava hay increased rumen $NH_3-N$ and milk urea nitrogen (MUN) (p<0.05). Cassava hay tended to increase milk production and 4% FCM. Milk protein increased in cows fed cassava hay (p<0.05). Moreover, cassava hay could reduce concentrate levels in dairy rations thus resulting in increased economic returns. Cassava hay can be a good source of forage to reduce concentrate supplementation and improve milk quality.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.50 no.3
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• pp.181-192
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• 2022

Active vibration control system(AVCS) for helicopter enables to control the vibration generated from the main rotor and has the superb vibration reduction performance with low weight compared passive vibration reduction device. In this paper, FxLMS algorithm-based vibration control software of the light civil helicopter tansmits the control command calculated using the signals of the tachometer and accelerometers to the circular force generator(CFG) is developed and verified. According to the RTCA DO-178C/DO-331, the vibration control software is developed through the model based design technique, and real-time operation performance is evaluated in PILS(processor in-the loop simulation) and HILS(hardware in-the loop simulation) environments. In particular, the reliability of the software is improved through the LDRA-based verification coverage in the PIL environments. In order to AVCS to light civil helicopter(LCH), the dynamic response characteristic model is obtained through the ground/flight tests. AVCS configuration which exhibits the optimal performance is determined using system optimization analysis and flight test and obtain STC certification.

• Journal of the Korean Geosynthetics Society
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• v.22 no.3
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• pp.11-25
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• 2023

In this study, the design and numerical analysis method of the inclined self-supported wall using cement treated soil were studied. In the case of the inclined self-supported wall, the active earth pressure decreased due to the decrease in the coefficient, Ka according to the slope (angle) and the weight decreasing effect, thereby increasing the overall stability. The wall with the slope caused a change in failure mode from overturning to sliding on the excavation side, and the optimal slope was evaluated to be about 10°. Compared to the strength reduction method, the overall stability in numerical analysis results in conservative results in limit equilibrium analysis, so it was found that this method should be attended when designing. As a result of the parameteric study, the stability on bearing capacity and compression failure did not significantly increase above the slope of 10° when the surcharge was small (about 20kPa or less). In the case of cohesion of the backfill, The results similar to numerical analysis were found to consider cohesion. It was evaluated that stability on sliding, oveturning, shear, and tension failure increases in proportion to the thickness of the wall, but there is no significant change in the stability on the bearing capacity and compressive failure regardless of the thickness of the wall above a certain angle (about 10°).

• Journal of Animal Science and Technology
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• v.49 no.4
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• pp.471-480
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• 2007

The aim of the present study was to determine the effects of a low-energy finisher diet on feed and growth efficiencies and carcass traits of ‘high’-market weight (MW) finishing pigs and thereby to extrapolate optimal dietary energy level for the high-MW swine. A total of 160 (Yorkshire × Landrace) × Duroc-crossbred finishing gilts and barrows weighing approximately 90 kg were fed a low-energy (3,200 kcal DE/kg) diet (LE) or control (3,400 kcal) diet (CON) ad libitum in 16 pens up to 135- and 125-kg live weights, respectively, at which the animals were slaughtered and their carcasses were analyzed [2 (sex) × 2 (diet) factorial experimental design]. Average daily gain, average daily feed intake and feed efficiency did not differ between the two sex or diet groups. Backfat thickness was less (P<0.05) in LE (22.4 mm) than in CON group (24.3 mm) in gilts, but not in barrows (24.4 ± 0.4 mm). The percentage of C- & D-grade carcasses was over 90% because of the ‘over-weight’ problem in gilts, whereas in barrows, percentages of A plus B grades and C plus D grades were 79% and 21%, respectively. The yield percentage of each trimmed primal cut per total trimmed cuts (w/w) did not differ between the two sex or diet groups. Physicochemical characteristics of longissimus muscle including color (lightness and redness), pH, drip loss and chemical composition, which overally were within the range of normal carcass, also did not differ between the two sex or diet groups. In conclusion, both LE and CON are judged to be adequate for the high-MW swine during the latter finishing period. If fat deposition of a given herd of high-MW pigs needs to be suppressed by a dietary treatment, the energy content of the diet will have to be reduced to a level lower than 3,200 kcal DE/kg.

• Journal of the Korean Wood Science and Technology
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• v.44 no.1
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• pp.85-95
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• 2016

In this study, furfural, which is one of the value-added chemicals, was produced from the hydrolyzate of Quercus mongolica using dilute acid pretreatment, and the optimal pretreatment condition was determined by Response Surface Methodology (RSM) to obtain high yield of furfural. Based on Central Composite Design, the pretreatment experiment was designed with parameters such as reaction temperature ($X_1$), acid concentration ($X_2$), and reaction time ($X_3$) as independent variables, while dependent variable was furfural concentration (Y), and furfural yield (Z) was shown as percentage of Y per a dry weight basis. According to results of RSM, it was confirmed that reaction temperature ($X_1$) was the most influence factor and reaction temperature ($X_1$)-acid concentration ($X_2$) was the most significant interaction factor on furfural yield. Also, the optimal condition for the highest furfural yield was predicted at reaction temperature of $184^{\circ}C$, acid concentration of 1.17%, and reaction time of 5 min by RSM, and expected maximum yield of furfural was 6.37%. Experimentally, the maximum yield of furfural produced at above optimal condition was 6.21%, and it was considerably similar with the predicted value, and therefore the model for furfural production from the hydrolyzate of Quercus mongolica during dilute acid pretreatment could be built using RSM.