• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.9
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• pp.128-133
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• 2020

This study was conducted to demonstrate the manufacturing process for producing high-quality solar salt. The design criteria of the manufacturing process, which was studied in a previous study, was applied to an actual manufacturing system to evaluate its performance. The design factors applied were the drying air temperature and the temperature of the washing water. They were 100℃ or less and 10℃ or less, respectively. Two standards were applied to the process performance evaluation. Standard (I) was the international food standard for solar salt, and standard (II) was the quality standard for high-quality solar salt production. The main quality evaluation items were the moisture content and salinity, and the color characteristics were also measured (p<0.05). The manufacturing process of solar salt consisted of five steps, and the quality change was measured for each step. The measured quality was appropriate to the standard (I) from the third-step process. In addition, the quality of the high-quality solar salt was suitable for the standard (II) from the fourth-step process. Therefore, the performance of the proposed solar salt production process met international standards. The improvements in the production of high-quality solar salt will improve international competitiveness in the future.

• Korean Journal of Food Science and Technology
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• v.50 no.2
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• pp.143-151
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• 2018

The quality and physicochemical characteristics of the soybean flours after germination and roasting were evaluated to partly fulfill the purpose of establishing quality standards of soybean flours for each of their applications. Moisture content of roasted soybean flours decreased significantly based on the roasting conditions, and crude ash, protein, and fat content increased. Water binding capacity increases with an increase in roasting temperature and time; however, water solubility index and swelling power decreased. The lightness of roasted soybean flour decreased significantly, and its redness and yellowness increased in intensity. Phenolic compounds and radical scavenging activity of roasted soybean flour increased with an increase in roasting temperature and time. 2,2'-Azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) radical scavenging activity of roasted soybean flour without and with germination was 380.88-537.32 and 419.34-587.99 mg TE/100 g, respectively. Consequently, it is necessary to set quality standards for each application, considering the quality and antioxidant properties of roasted soybean flours.

• Plant Journal
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• v.10 no.2
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• pp.38-47
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• 2014

Renewable Portfolio Standards was introduced into the system in Korea in 2012. Interest in the unutilized and renewable energy sources is increasing. and these being actively investigated. An organic rankine cycle has emerged as an alternative in order to take advantage of bio-gas engine heat of sewage treatment plants whose capacity is 1500 kW. The organic rankine cycle power system was simulated by a simulator which is a commercial program of power plant design and performance analysis. The biogas engine is operated by $460^{\circ}C$ and 2.7 kg/s flow rate in the sewage treatment plant. Working fluids(R-601a, R-123, R-245fa) are selected to use in ORC power system in this temperature range. It was the isopentane that is the best performance among three working fluids. It could be obtained net power of 163.1 kW and efficiency of 13.66% from isopentane in the simulation.

• Journal of the Korean Applied Science and Technology
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• v.35 no.4
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• pp.1134-1144
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• 2018

Cetane Number is one of the quality standard for diesel, which assesses the compatibility of ignition quality of diesel compression in diesel engines. Cetane number must be upper 52 to keep the recent diesel quality standards. It is known that if cetane number is high, there will be shorter ignition delay periods than being lower. On the other hands, if cetane number is too high that exceeds the quality standard, there will increase the air pollution and decrease of the fuel efficiency because incomplete combustion. In South Korea, various methods are being used to measure the cetane number such as cetane number that used CFR engine, cetane index from calculate density and distillation temperature and derived cetane number to make up for CFR engine that ignition delay in high temperature is implemented. In this study will be conducted by collecting the diesel from the major oil companies, and try to analyze the correlation between the different methods of cetane number with various factors. At the results of this study, it was shown that the cetane index is high then cetane engine and derived cetane number. therefore it will be necessary to additional research for out of cetane number quality standards.

• Journal of Food Hygiene and Safety
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• v.38 no.4
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• pp.236-245
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• 2023

In this study, the quality safety limit period of seven types of bakery bread was analyzed, and their use-by date was calculated. For evaluating product quality, storage conditions were set as 5, 15, 25, and 35℃ for 50 days, and moisture, microorganisms, sensory characteristics, and dominant bacteria were examined. The quality and safety standards followed the Korea Food Code and Korean industrial standards (KS). The results showed that all products stored at 5℃ satisfied the standard for bacterial count for day 50, but the sensory quality was below the standard level. Samples stored at 15℃ showed high variability from 3-39 days. At 25℃, a quality safety limit period of 2-20 days was set, and one sample was found to have the same shelf life. Bread stored at 35 ℃ had the shortest quality safety limit period. Considering a safety factor of 0.87, a use-by date period of 1.7-13.1 days was calculated. Therefore, setting the use-by date according to the product type is necessary, even for the same product category. Among the bread products sold in bakeries, those managed as room temperature products (1-35℃) can be distributed and stored in a temperature range of up to 35℃. Overall, this study demonstrates the importance of setting a quality retention period based on the product characteristics and carefully considering the safety factor.

• Journal of the Korean Vacuum Society
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• v.18 no.2
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• pp.108-115
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• 2009

The superlattice infrared photodetector (SLIP) with an active layer of 8/8-ML InAs/GaSb type-II strained-layer superlattice (SLS) of 150 periods was grown by MBE technique, and the proto-type discrete device was defined with an aperture of $200-{\mu}m$ diameter. The contrast profile of the transmission electron microscope (TEM) image and the satellite peak in the x-ray diffraction (XRD) rocking curve show that the SLS active layer keeps abrupt interfaces with a uniform thickness and a periodic strain. The wavelength and the bias-voltage dependences of responsivity (R) and detectivity ($D^*$) measured by a blackbody radiation source give that the cutoff wavelength is ${\sim}5{\mu}m$, and the maximum Rand $D^*$ ($\lambda=3.25{\mu}m$) are ${\sim}10^3mA/W$ (-0.6 V/13 K) and ${\sim}10^9cm.Hz^{1/2}/W$ (0 V/13 K), respectively. The activation energy of 275 meV analyzed from the temperature dependent responsivity is in good agreement with the energy difference between two SLS subblevels of conduction and valence bands (HH1-C) involving in the photoresponse process.

• Journal of the Korean Recycled Construction Resources Institute
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• v.8 no.1
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• pp.64-71
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• 2020

The purpose of this study was to evaluate the North Korea cement industry and technology status by comparing and analyzing the cement standards and properties of South and North Korea. In the literature study, data on North Korea's cement industry and standards were collected and analyzed through the Ministry of Unification's North Korea Data Center and other agency. The facilities, classification, and quality standards of South and North Korea cements were compared. In an experimental study, a survey on the quality of cement in North Korea was carried out through physical and chemical analysis experiments by obtaining a small amount of cement from North Korea, and compared with domestic cement. As a result, North Korea cement was of lower quality than South Korean cements. North Korea cement had lower C₃S and higher C₂S than South Korea cement, especially the residue content was much higher. In addition, North Korea cement had about 50% of the compressive strength of cement in South Korea because the clinker was not fired at a sufficient temperature due to the poor performance of the cement facilities in North Korea.

• Journal of the Korean Society for Nondestructive Testing
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• v.23 no.4
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• pp.315-321
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• 2003

The integrity of the turbine rotors can be assessed by measuring the material properties at service temperature. In order to evaluate the remanent life of turbine rotor steel nondestructively, a measurement system of reversible magnetic permeability using an alternating perturbing magnetic field was constructed. We present a new non-destructive method to evaluate the remanent life of 1Cr-1Mo-0.25V steel using the value of reversible magnetic permeability. This method is based on the existence of reversible magnetic permeability in the differential magnetization around the coercive field strength. We measured the first harmonics voltage induced in a coil using a lock-in amplifier tuned to an exciting frequency. The Results of reversible magnetic Permeability and Wickers hardness on the aged samples show that the peak interval of reversible magnetic permeability (PIRMP) and Vickers hardness decreases as aging time increases. A softening curve is obtained from the correlation between Vickers hardness and the PIRMP. This curve can be used as a non-destructive method to evaluate the remanent life of turbine rotor steel.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.5
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• pp.570-576
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• 2018

In reinforced concrete structures, the joints of ordinary rebars are usually lap joints, which are bound by binding wires with rebars, and mechanical joints by couplers. In domestic design standards (concrete design code), welded lap joints are restricted for ordinary rebars, but overseas standards allow welded lap joints of ordinary rebars through pre-heating. This study investigated the domestic and international standards/criteria and evaluated the fracture strength by performing the tensile test on the lap welded joint of SD400 grade rebars, which is used the most in the construction sites. The weld length of the specimen for weld lap joints is based on the minimum weld length (8d) given in the KS standard (KS B ISO 17660-1). According to AWS D1.4, the preheating temperature was set to $150^{\circ}C$ for D19 and below, and $260^{\circ}C$ for D22 and above. In the test results, the tensile strength of rebars with welded lap joints exceeded the required strength (125% of the yield strength) according to the concrete design code. To analyze the effect of preheating, the tensile strength of the welded rebars after preheating was not significantly different from that of the welded rebars without preheating. The carbon equivalent content (Ceq) of the rebars used in the test was 0.45% or less. Under AWS D1.4, no preheating is required if the carbon equivalent is less than 0.45%. All specimens with a welded lap length of 8d failed by a bar fracture. The effect of preheating was confirmed to be insignificant due to the low carbon equivalent of the rebar.

• Journal of the Korean Magnetics Society
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• v.15 no.4
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• pp.246-249
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• 2005

The blue-color emitting phosphor powder, $CaMgSi_{2}O_6:Eu^{2+}(CMS:Eu^{2+})$ was synthesized by the solid-state reaction method. The synthesized powder was annealed from room temperature to $1,100^{\circ}C$ in air. Its PL property and valence state of Eu atoms was measured by the photoluminescence (PL) and the electron paramagnetic resonance (EPR) spectrometers, respectively. The PL intensity was stable to $700^{\circ}C$, but drastically decreased to $1,100^{\circ}C$. The behavior of EPR intensity was very similar to the PL intensity. The EPR measurement showed that decreased intensity of the PL was caused to the oxidation from the ion $Eu^{2+}$ to $Eu^{3+}$ ions. The EPR spectrometer was powerful as a tool that could distinguish between the valence states of Eu atom as a dopant in various phosphors.