• Food Science and Preservation
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• v.31 no.3
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• pp.423-432
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• 2024

In this study, a vacuum tumbler with 4 impellers (DVT) was designed and applied for thawing frozen pork (vacuum -60 kPa, jacket 35℃, 1 rpm). Quality characteristics of the thawed pork were compared with those of industrially thawed meat by natural air at room temperature (NAT) and imported vacuum tumbler (IVT). The thawing time for frozen pork (303.36 kg) using DVT (165 min) was much shorter than that of NAT (4,200 min). DVT-thawed pork had lower drip loss (0.85%) than NAT (2.08%). DVT-thawed pork showed a pH of 5.92, a total bacterial count of 1.96±0.02 log CFU/g and no coliforms. Deteriorations in fat (TBARS 0.31±0.01 MDA mg/kg) and protein (VBN 5.67±1.98 mg%) in DVT-thawed pork were significantly lower than those of NAT (p<0.05). DVT-thawed pork had a high water-holding capacity (WHC, 97.5%). The hardness (34.59±0.46 N) and chewiness (188.21±0.17) of cooked DVT-thawed pork were about 5-6 times lower than those of NTA. Microstructure (SEM) showed myofibrillar damage in NAT-thawed pork, whereas dense myofibrillar structure was observed in DVT-thawed pork. DVT was better or similar to IVT in all evaluation parameters. The designed DVT is expected to be used as an efficient thawing method in terms of processing time and yield and to produce thawed meat with high WHC, soft texture, and low spoilage by minimizing tissue damage.

• Nuclear Engineering and Technology
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• v.18 no.3
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• pp.218-227
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• 1986

Studies were conducted to determine the extent of oxidation and same of the mechanical property changes of Zircaloy-4 fuel cladding after it was exposed to hot steam environment. The purpose of these tests was to provide some informations on the embrittlement behavior of CANDU type fuel cladding, which could be experienced under the loss-of-coolant accident conditions. The Zircaloy fuel cladding tubes were exposed in a steam environment at the temperature of 90$0^{\circ}C$, 1,00$0^{\circ}C$. The growth of the ZrO$_2$ layer combined with an oxygen rich $\alpha$-phase layer into the Zircaloy tube material was found as a function of time t and temperature of steam exposure, E=1.1√Dt+0.002 where D is a temperature dependent diffusion coefficient. The tensile strength of the specimens exposed for a short period increased but decreased continuously with further exposure. The circumferential elongation was drastically changed with the exposure time while the hoop strength did't decrease greatly. The X-ray measurement of preferred orientation of the Zircaloy tube material indicated that grains in the as received tube were oriented such that the poles of the basal (0001) planes were predominantly radial, while the poles of the basal plane in the tube materials heattreated at 1,00$0^{\circ}C$ were oriented tangentially. It appears that this reoriented texture may contribute to lessening the decrease of the hoop strength of the heat treated Zircaloy tube material.

• Journal of Advanced Marine Engineering and Technology
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• v.40 no.3
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• pp.228-234
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• 2016

As a college dormitory has the features of high dwelling density and a floating population that becomes crowded during particular times, when a disaster such as a fire occurs, it has the risk of causing much loss of life. In this study, the fire simulation program Fire Dynamics Simulator (FDS), is used to predict the risk when a fire occurs, to analyze the problem, and to suggest an improvement plan for a new cadet dormitory at an university in Korea. The research results are as follows. When a fire occurred in the ironing room inside the cadet dormitory, a smoke detector operated after 65 seconds. Thirteen seconds later, a sprinkler started to operate. The temperature and carbon monoxide density reached the limit value at 241 and 248 seconds, respectively. Because the limit visibility value was reached within 66 seconds after the occurrence of a fire, it is predicted that preparation must be finished and evacuation should begin within 1 minute after the fire occurs, in order to have no casualties. Synthesizing this dormitory fire risk prediction result, the visibility value is considered to be the most dangerous factor for personal safety. Because of this, installing a smoke extraction system is suggested to secure visibility. After the installation of a smoke extraction system, the problem of smoke diffusion in the corridors improved.

• International Journal of Highway Engineering
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• v.13 no.3
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• pp.39-49
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• 2011

The porous pavement system is widely considered very effective in urban street because of its various benefits on safety and environment, but the pavement thickness design system has not been established yet. In porous pavement system. rainwater penetrates to the subgrade through porous pavements layers. Porous pavements are expected to reduce or alleviate the problems caused by impermeable pavement layer such as flood damage due to heavy rain in the city, drainage load, disorder in ecosystem, and heat island. However, its structural design methods in traffic roads has not been made mainly because of not being able to consider adequately the effect of rainwater on subgrade strength. In this study, structural design method of porous pavements is suggested after considering the subgrade weakness due to rainwater and numerical mechanical analysis. It is noted that elastic modulus of subgrade is reduced by 20% as subgrade moisture content is increased by 2% at optimum moisture content in the literature review. As a result of both finite element analysis and strength loss of subgrade by the existing design method, it is necessary to increase subbase thickness about 30cm in porous pavements compared with the existing traffic road pavement system. It is similar to premium thickness of structural design of porous pavements in Japan.

• Journal of the Korea Concrete Institute
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• v.24 no.6
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• pp.727-735
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• 2012

Recently, a high-strength strand of 2400 MPa was developed using domestic technologies. In 2011, KS D 7002 was revised to cover the newly developed high-strength strands to support their practical usage. Presently, however, discussions and evaluations are not sufficient on the mechanical properties of the strands and their performance in structural members. Also, there were no detailed reviews on the need to revise the current design code for practical use of the high-strength strands. In this study, flexural behavior of a member with the high-strength strands was estimated through sectional analysis and a review and comparison of the domestic and foreign design codes were conducted considering the analysis results. Also, the need for the revision of the design code was discussed. Such discussion especially focused on the estimation of the stress in strand, which related with various issues such as determination methods for yield point of strands, time-dependent loss of prestressing force, estimation of stress in strand at member failure, and net strain limit for ductile failure of member. The discussion revealed that some parts in the design code need a revision and the further studies are required.

• Corrosion Science and Technology
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• v.13 no.2
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• pp.70-80
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• 2014

Duplex stainless steels with nearly equal fraction of the ferrite(${\alpha}$) phase and austenite(${\gamma}$) phase have been increasingly used for various applications such as power plants, desalination facilities due to their high resistance to corrosion, good weldability, and excellent mechanical properties. Hyper duplex stainless steel (HDSS) is defined as the future duplex stainless steel with a pitting resistance equivalent (PRE=wt.%Cr+3.3(wt.%Mo+0.5wt.%W)+30wt.%N) of above 50. However, when HDSS is welded with gas tungsten arc (GTA), incorporation of nitrogen in the Ar shielding gas are very important because the volume fraction of ${\alpha}$-phase and ${\gamma}$-phase is changed and harmful secondary phases can be formed in the welded zone. In other words, the balance of corrosion resistance between two phases and reduction of $Cr_2N$ are the key points of this study. The primary results of this study are as follows. The addition of $N_2$ to the Ar shielding gas provides phase balance under weld-cooling conditions and increases the transformation temperature of the ${\alpha}$-phase to ${\gamma}$-phase, increasing the fraction of ${\gamma}$-phase as well as decreasing the precipitation of $Cr_2N$. In the anodic polarization test, the addition of nitrogen gas in the Ar shielding gas improved values of the electrochemical parameters, compared to the Pure Ar. Also, in the erosion-corrosion test, the HDSS welded with shielding gas containing $N_2$ decreased the weight loss, compared to HDSS welded with the Ar pure gas. This result showed the resistance of erosion-corrosion was increased due to increasing the fraction of ${\gamma}$-phase and the stability of passive film according to the addition $N_2$ gas to the Ar shielding gas. As a result, the addition of nitrogen gas to the shielding gas improved the resistance of erosion-corrosion.

• The Journal of the Acoustical Society of Korea
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• v.39 no.6
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• pp.524-532
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• 2020

In this study, noise radiated from a high-speed fan-motor unit for a cordless vacuum cleaner is reduced by designing splitter blades on the existing impeller. First of all, in order to investigate the flow field through a fan-motor unit, especially impeller, the unsteady incompressible Reynolds-Averaged Navier-Stokes (RANS) equations are numerically solved by using computational fluid dynamic technique. With predicted flow field results as input, the Ffowcs Williams-Hawkings (FW-H) integral equation is solved to predict aerodynamic noise radiated from the impeller. The validity of the numerical methods is confirmed by comparing the predicted sound pressure spectrum with the measured one. Further analysis of the predicted flow field shows that the strong vortex is formed between the impeller blades. As the vortex induces the loss of the flow field and acts as an aerodynamic noise source, supplementary splitter blades are designed to the existing impeller to suppress the identified vortex. The length and position of splitter are selected as design factors and the effect of each design factor on aerodynamic noise is numerically analyzed by using the Taguchi method. From this results, the optimum location and length of splitter for minimum radiated noise is determined. The finally selected design shows lower noise than the existing one.

• Applied Chemistry for Engineering
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• v.9 no.6
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• pp.884-888
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• 1998

Effects of heating time under high temperature on the thermal and mechanical properties of neutron shielding materials based on modified (KNS-102), hydrogenated(KNS-106) bisphenol-A type epoxy resin and phenol-novolac(KNS-611) type epoxy resin for radioactive material shipping casks have been investigated. At early stages, the initial decomposition temperatures of the shielding materials of KNS-102, KNS-106 and KNS-611 increased with the heating time under high temperature, but it was rarely affected by the heating time in the later stages. In addition, the thermal conductivities of KNS-102 and KNS-106 decreased with heating time, but that of KNS-611 increased with the heating time. On the contrary, the thermal expansion coefficients of neutron shielding materials decreased with increase of heating time. At the high temperature, the tensile strength and flexural strength of the shielding materials of KNS-102 and KNS-611 increased with heating time, but those of KNS-106 decreased with increase of heating time. And the heating time under high temperature on the neutron shielding materials did not show measurable loss of weight and hydrogen content.

• The Journal of Korean Medicine Ophthalmology and Otolaryngology and Dermatology
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• v.13 no.2
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• pp.112-139
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• 2000

I examined and referred to literatures of every generations on the nicknames, causes, herb medications and acupucture treatments of ptosis(上胞下垂). And then the results were obtained as follows. We've compared and analyzed Occidental and Oriental medical causes, symptoms and treatments of Primary trigeminal neuralgia and wanted to get better effects by a cooperative analysis. So the examination and analysis of the recent treatment tendency and reference bibliography show the following results. 1. Trigeminal neuralgia is nerve systematic disease appearing in the distribution scope of trigeminal nerve. It's characterized by extreme pain accompanying with a repeated and simultaneous fit from several seconds to 1-2 minutes. 2. Though there are many hypothesis on the trigeminal neuralgia, but now many doctors agree that when trigeminal nerve is under the local out of sheath conditions resulting from receiving a chronic stimulus, and the nucleus of trigeminal nerve fire, owing to decrease of pain control function and abnormal occurrence of action potential, it would be appeared. 3. The Oriental medical name of trigeminal neuralgia is generally Dootong, Doopoong, Myuntong, Pyundootong, Pyundoopoong, and Myuntong is the nearest in Occidental medicine. 4. The Oriental medical cause of trigeminal neuralgia is usually divided into Wekam and Naesang. The first one is caused by Poonghan, Poongyul, Damhwa and wicked energy enter into the body, the mechanical energy is obstructed and can't move any more, so the pain appears by them. The other cause is the hurt by emotion. And it would be loss of the transportain of liver and obstructed, so result into Kanwulhwahwa, Kanpoongnaedong and the pain appears. 5. There are two methods of curing trigeminal neuralgia. As a medication, primary method is prescribing Carbamazepine and the second is using Phenytoin or Baclofen. And as a operation, Drug injection of trigeminal nerve, Amputation of branches of trigeminal nerve, Retrogasserian glycerol rhizotomy, Radiofrequency gangliolysis, Neurovascular decompression can be used. 6. There are several herb medicines for Trigeminal neuralgia. First, Chungung is good for Hwaejeetong, Keopoongjedam, Hwalhyuljeetong. Second, Jeongal, Jiryong, Okong is used for Sikpoonghekyung, Tongkyungjeetong. Third, Baekjee, Sesin, Cheonma, Manhyungja is efficacious in Sinonhepyo. Sanpoongjeetong. Fourth, for falling of liver's Wulhwa, Yongdamcho, Hyungge, Kukwha can be used. And also Saengjihwang, Hwangkm is good for going down the fever of Yangmyungwiyul and finally, Baekkangjam. Moryu can be effective for Jaumjamyang, Haekyungjitong. The other medicines can be used as assistant analgesics, and it also efficacious. 7. Generally the points of pain on the face and the points of Soyangkyung and Yangmyungkyung is used for Acupuntual therapy, because the two meridians passed on the face. Hakwan. Sabaek, Kwanryo, Keoryo, Hyubkeo, Taeyang, Jeechang, Younghyang, Eoyo, Chanjuk. Yangbaek. Sajukkong. Dooyoo, Kwangsangjum, Sengjang, Poongjee is used for taking near point and Joksamlee, Naejung, Habkok is used for taking distant point. 8. Dansam or Danggui injection which have a effect for Hwalhyulhwaeo, Sokyunghwalak and Vit B1, Vit B2, Vit B12, $2\%$ Hydrochloroprocaine, $1\%$ Lidocaine injection to pain point for local analgesics had so good effect. And external application and moxibustion are used for another treatment. 9. It proved that through mouse model, both Herb medication group and Drug medication group are efficacious for trigeminal neuralgia similarly and also the cooperative medication group shows more effective result than the only drug medication group.

• Journal of Advanced Marine Engineering and Technology
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• v.8 no.1
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• pp.17-36
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• 1984

Since 1973, the competition on the development of fuel saving type internal combustion engines has become severe by the two times oil shock, and new type engines are reported every several months. Whenever these new type engines are developed, new designs are required and they will be offered in the market after performing the endurance test for a long time. But the engine market is faced with a heavy burden of finance, as the developing of a new engine requires tremendous expenses. For this reason, the computer simulation method has been lately developed to cope with it. The computer simulation method can be available to perform the reasonable research works by the theoretical analysis before carrying out practical experiments. With these processes, the developing expenses are cut down and the period of development is curtailed. The object of this study is the development of simulation computer program for the small naturally aspirated four-stroke diesel engine which is intended to product by the original design of our country. The process of simulation is firstly investigated for the ideal engine cycle, and secondly for the real engine cycle. In the ideal engine cycle, each step of the cycle is simulated by the energy balance according to the first law of thermodynamics, and then the engine performance is calculated. In the real cycle imulation program, the injection rate, the preparation rate and the combustion rate of fuel and the heat transfer through the wall of combustion chamber are considered. In this case, the injection rate is supposed as constant through the crank angle interval of injection and the combustion rate is calculated by the Whitehouse-Way equation and the heat transfer is calculated by the Annand's equation. The simulated values are compared with measured values of the YANMAR NS90(C) engine and Mitsubishi 4D30 engine, and the following conclusions are drawn. 1. The heat loss by the exhaust gas is well agree with each other in the lower load, but the measured value is greater than the calculated value in the higher load. The maximum error rate is about 15% in the full load. 2. The calculated quantity of heat transfer to the cooling water is greater than the measured value. The maximum error rate is about 11.8%. 3. The mean effective pressure, the fuel consumption, the power and the torque are well agree with each other. The maximum error is occurred in the fuel consumption, and its error rate is about 7%. From the above remarks, it may be concluded that the prediction of the engine performance is possibly by using the developed program, although the program needs to reform by adding the simulation of intake and exhaust process and assumping more reliable mechanical efficiency, volumetric efficiency, preparation rate and combustion rate.