• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.32 no.9
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• pp.103-113
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• 2004

The satellite is exposed to the severe vibration environments such as random vibration environments such as random vibration, acceleration, shock, and acoustics during launch ascent and transportation. It is also faced with various space environments such as thermal vacuum, radiation and microgravity during the mission life. The satellite should be designed, manufactured, assembled and tested to be able to endure in these harsh environments. This paper addresses the results of the structural and thermal design and analyses for the HAUSAT-1 picosatellite which is scheduled to launch in the first quarter of 2005 by Russian launch vehicle "Dnepr". The qualification vibration and thermal vacuum tests have been conducted and passed at the satellite level to ensure that the HAUSAT-1 mechanical system was designed to be stable with enough margin.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.43 no.3
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• pp.68-76
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• 2020

In a series of recent launch tests, North Korea has been improving the firepower of its missiles that can target South Korea. North Korea's missiles and submarines are capable of threatening targets in South Korea and are likely faster and more covert than the systems previously seen in North Korea. The advanced threats require that ROK Navy should not only detect them earlier than ever but also response quicker than ever. In addition to increasing threats, the number of young man that can be enlisted for military service has been dramatically decreasing. To deal with these difficulty, ROK navy has been making various efforts to acquire a SMART warship having enhanced defense capability with fewer human resources. For quick response time with fewer operators, ROK Navy should improve the efficiency of systems and control tower mounted on the ship by promoting the Ship System Integration. Total Ship Computing Environment (TSCE) is a method of providing single computing environment for all ship systems. Though several years have passed since the first proposal of TSCE, limited information has been provided and domestic research on the TSCE is still in its infancy. In this paper, we apply TSCE with open architecture (OA) to solve the problems that ROK Navy is facing in order to meet the requirements for the SMART ship. We first review the level of Ship System Integration of both domestic and foreign ships. Then, based on analyses of integration demands for SMART warship, we apply real time OA to design architecture for TSCE from functional view and physical view. Simulation result shows that the proposed architecture has faster response time than the response time of the existing architecture and satisfies its design requirements.

• Food Science and Preservation
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• v.17 no.6
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• pp.800-806
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• 2010

The aim of this research is to develop recipe of kimchi beverage made of sun-dried salt. A distinction between this recipe with existing ones is the Korean traditional ingredient, sun-dried salt. The variety and amount of recruitment on the beverage was established after its characteristics were investigated by sensory tests. Preference of sweetening agent for the beverage was oligosaccharide > honey > sugar powder > sugar > aspartame > pear juice. While sensory evaluation was conducted on color, flavor and overall acceptance, the overall acceptance scores are as following; 6.24 for watery radish kimchi, 6.00 for white kimchi and 5.76 for Korean cabbage kimchi. Among other beverages, watery radish kimchi beverage was preferred. Amount of kimchi for the beverage was most suitable at 10 % of the contents. It was the same with all the other beverages. When the products were stored in normal temperature, the evaluation scores dropped for all sensory items as time passed.

• Journal of Environmental Health Sciences
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• v.35 no.3
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• pp.226-234
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• 2009

The main objective of this study was to evaluate the effects on shape and size, compressive strength, water absorption and heavy metals leaching with various weight mixing ratios in waste ash brick products using waste recycling MSWI(Municipal Solid Waste Incinerator) bottom ash, steel slag and waste building material. The manufacturing processes for the waste ash brick consist of screening, mixing, conveyor transmission, compaction.forming, and curing steps of raw materials. The weight mixing ratios of steel slag around bottom ash were adjusted within the ranges of 10% to 30%. The reported results show that the width and thickness of the manufactured waste ash brick could be satisfied with $90{\pm}2mm\;and\;57{\pm}2mm$, respectively which are K.S. standards of products qualities. And in case of length, only 20-Ba50Ss30, 20-Ba60Wb20 and 20-Ba50Wb30 for the mixing ratios could be satisfied with $190{\pm}2mm$ that is K.S. standards of products quality. The compressive strength and water absorption for 20-Ba50Ss30 and 20-Ba70Wb10 were over $8N/mm^2$ and below 15% respectively that are K.S. standards of manufactured waste ash brick. The results of tests for the heavy metals leaching in the all manufactured waste ash bricks are also passed to the wastes management regulations. The cost analysis of 20-Ba50Ss30 is evaluated. The manufacturing cost is evaluated 34.3 won/brick with 8 hours and 20tons of raw material per day. Incinerators with problems in bottom ash disposal can therefore derive significant benefits from the application of waste ash brick production.

• Journal of Wetlands Research
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• v.12 no.2
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• pp.67-73
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• 2010

This study was performed to figure out what would be effective to maintain good water quality in the retention pond which was badly polluted before. In order to keep the good water quality of the retention pond it is necessary to prevent outer non-point source pollutants from flowing into the pond. In this study, we proposed to use porous slag as a blockage of the inflow into the pond from external non-point sources. We experimented with porous slag nets to see how the water is effected. With the results of the experiments, we found out there is a close correlation($r^2=0.9765$) between contact time and the removal rate of phosphorus, therefore we can conclude that contact time affects removal rate greatly. Synthetic wastewater, activated sludge effluent, and sewage were passed through a porous slag packed bed, both phosphorus and the suspended solid in water were removed highly. With the results of these tests, we proposed to set up a porous slag packed bed inside of the retention pond and revetment to prevent external non-point source pollutants flowing into the retention pond.

• Korean Journal of Soil Science and Fertilizer
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• v.18 no.4
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• pp.352-358
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• 1985

Loss of cationic zeolites saturated with different ions, sodium, potasium, ammonium, magnesium and calcium ions, and changes of hydraulic conductivity were investigated in labortory. The 0.5 to 1mm sands and the zeolite particles passed 0.1mm sieve were used in the column tests. The amount of zeolite particle loss was in order of Na- > K- > $NH_4-$ saturated zeolites, and little loss was observed from Mg and Ca saturated zeolites. The loss of zeolite particles was mainly due to dispersion in solution, which was prominant when 0.01N dilute mono ionic solution and distilled water were percolated. The results also showed that the changes in hydraulic conductivity were greater in the columns where the loss of dispersed zeolite particles was higher.

• The Journal of Advanced Prosthodontics
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• v.15 no.1
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• pp.33-43
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• 2023

PURPOSE. This study investigated the physical and mechanical changes in the titanium base of three different hybrid abutment materials after cyclic loading by estimating the post-load reverse torque value (RTV), compressive side fulcrum wear pattern of titanium base, and surface roughness. MATERIALS AND METHODS. A total of 24 dental implants were divided into three groups (n = 8 each): Group Z, LD, and P used zirconia, lithium disilicate, and polyetheretherketone, respectively, for hybrid abutment fabrication. RTV was evaluated after cyclic loading with 50 N for 1.2 × 10⁶ chewing cycles. The compressive sides of the titanium bases were analyzed using a scanning electron microscope, and the roughness of the affected areas was measured using an optical profilometer after loading. Datasets were analyzed using Kruskal-Wallis test followed by Mann-Whitney tests with the Bonferroni correction (α = .05). RESULTS. Twenty-three samples passed the test; one LD sample fractured after 770,474 cycles. Post-load RTV varied significantly depending on the hybridabutment material (P = .020). Group P had a significantly higher median of post-load RTVs than group Z (16.5 and 14.3 Ncm, respectively). Groups LD and P showed minor signs of wear, and group Z showed a more pronounced wear pattern. While evaluating compressive side affected area roughness of titanium bases, lower medians were shown in group LD (Ra 0.16 and Rq 0.22 ㎛) and group P (Ra 0.16 and Rq 0.23 ㎛) than in group Z (Ra 0.26 and Rq 0.34 ㎛); significant differences were found only among the unaffected surface and group Z. CONCLUSION. The hybrid abutment material influences the post-load RTV. Group Z had a more pronounced wear pattern on the compressive side of titanium base; however, the surface roughness was not statistically different among the hybridabutment groups.

• Journal of the Korean Geotechnical Society
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• v.24 no.4
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• pp.15-21
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• 2008

Long term changes of hydraulic properties and tensile strength of natural fiber drain (NFD) are analyzed and compared with those of intact NFD's. NFD was buried in distilled water, two types of seawater and clay soils obtained in southern and western parts of Korea, Kwang-Yang and Si-hwa. Specimens are taken out in 0, 3, 9 and 18 month intervals, and durability tests of the NFD are performed. Hydraulic conductivity of the NFD samples decreased compared with that of intact NFD samples, because clay particles easily passed to coarsened mesh of filters and clogged the porous stone below and reduced hydraulic conductivity. Tensile strength of drains from the soil bucket is reduced larger than those in the seawater and the distilled water. Strength reduction was higher in summer than winter.

• Journal of KIBIM
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• v.13 no.3
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• pp.21-29
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• 2023

ChatGPT, a chatbot based on GPT large language models, has gained immense popularity among the general public as well as domain professionals. To assess its proficiency in specialized fields, ChatGPT was tested on mainstream exams like the bar exam and medical licensing tests. This study evaluated ChatGPT's ability to answer questions related to Building Information Modeling (BIM) by testing it on Korea's BIM expertise exam, focusing primarily on multiple-choice problems. Both GPT-3.5 and GPT-4 were tested by prompting them to provide the correct answers to three years' worth of exams, totaling 150 questions. The results showed that both versions passed the test with average scores of 68 and 85, respectively. GPT-4 performed particularly well in categories related to 'BIM software' and 'Smart Construction technology'. However, it did not fare well in 'BIM applications'. Both versions were more proficient with short-answer choices than with sentence-length answers. Additionally, GPT-4 struggled with questions related to BIM policies and regulations specific to the Korean industry. Such limitations might be addressed by using tools like LangChain, which allow for feeding domain-specific documents to customize ChatGPT's responses. These advancements are anticipated to enhance ChatGPT's utility as a virtual assistant for BIM education and modeling automation.

• Journal of the Korean Society of Clothing and Textiles
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• v.40 no.5
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• pp.921-935
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• 2016

This research analyzed the manual performance of firefighting protective gloves on global markets in order to suggest an evaluation method for firefighting protective gloves wearing comfort. We collected 13 types of firefighting gloves from domestic and international markets (7 types from Korea, 3 types form Europe, 2 types from the U.S and 1 type from Japan). We set the Don-Doff test as a basal requirement for moving toward to further manual performance tests that consist of: ASTM dexterity test, Minnesota dexterity test, Bennett hand tool test and ASTM torque test. All gloves were evaluated in dry and wet conditions, we included eight current male firefighters ($43.4{\pm}7.0yr$ in age, $173.1{\pm}4.4cm$ in height, $79.9{\pm}9.2kg$ in body mass) for the tests. Four gloves (1 Korea, 1 U.S, 1 Germany, and 1 Japan) out of thirteen firefighting gloves passed the Don-Doff test and had great subject preferences. There was no significant difference between dry and wet conditions on the ASTM dexterity test, Minnesota dexterity test, Bennett hand tool test and ASTM torque test. However, Japanese gloves had the greatest score and showed 3-4 times faster completion time on the ASTM dexterity test (p<.05), 1.2-1.5 times faster on the Minnesota dexterity test (p<.05), as fast as the bare hand on Bennett hand tool test (p<.05), and greater performance on the ASTM torque test compared to bare hand. In conclusion, Don-Doff test in wet conditions should be the first step for a mobility evaluation of domestic firefighting protective gloves; subsequently, a comprehensive test assorting ASTM, Minnesota, and Bennett test should be developed as a second step. The current ASTM torque test can be adopted as a third step. This three-step-method for evaluating firefighting protective glove mobility can be expected to expand into surveys of other safety gloves in Korea.