• Advances in materials Research
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• v.13 no.3
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• pp.183-194
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• 2024

D3 tools steel and 440C stainless steel (SS) are normally being employed for application such as knife blade and cutting tools. These steels are iron alloys which have high carbon and high chromium content. In this study, lab work focused on the microstructural and corrosion behavior of D3 tools steel and 440C SS after went through heat treatment processes. Heat treatments for both steels were started with normalizing at 1020 ℃, continue with hardening at 1000 ℃followed by oil quenching. Cryogenic treatment was carried out in liquid nitrogen for 24 hours. The addition of cryogenic heat treatment is believed to increase the hardness and corrosion resistance for steels. Both samples were then tempered at two different tempering temperatures, 160 ℃ and 426 ℃. For corrosion test, the samples were immersed in NaCl solution for 30 days to study the corrosion behavior of D3 tool steel and 440C SS after heat treatment. The mechanical properties of these steels have been investigated using Rockwell hardness machine before heat treatment, after heat treatment (before corrosion) and after corrosion test. Microstructure observation of samples was carried out by scanning electron microscopy. The corrosion rate of these steels was calculated after the corrosion test completed. From the results, the highest hardness is observed for D3 tool steel which tempered at 160 ℃(54.1 HRC). In terms of microstructural analysis, primary carbide and pearlite in the as-received samples transform to tempered martensite and cementite after heat treatment process. From this research, for corrosion test, heat treated 440C SS sample tempered with 426 ℃possessed the excellent corrosion resistance with corrosion rate 0.2808 mm/year.

• Transactions of Materials Processing
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• v.33 no.5
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• pp.348-353
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• 2024

The S355NL steel has garnered attention as a structural material for applications in extremely challenging environments owing to its excellent mechanical properties. This study investigated the hot deformation behavior of S355NL steel through compression tests conducted in a temperature range of 900-1200℃ and a strain rate range of 10^-3-1 s^-1 to explore the optimal processing parameters. The flow behaviors consisted of an initial rapid increase and subsequent plateau with a marginal decrease in stress. This phenomenon was interpreted in terms of microstructural evolution, such as dislocation density and dynamic recrystallization. The efficiency of power dissipation and instability domains were derived using the dynamic material model based on the compression test dataset, providing a series of processing maps. In contrast to conventional processing maps plotted for a single strain value, this study has established ten maps at a strain interval of 0.1. This approach allowed for the consideration of continuously variable strain parameters, which is inherent to an actual metal-forming process. The efficiency of power dissipation was strongly governed by the high temperatures (≥ 1100℃). The strain rates barely affected the efficiency, but it primarily contributed to the instability domains. The application of high strain rates (≥ 10^-1s^-1) generated a region of negative instability due to the absence of dynamic recrystallization and the presence of cracks at grain boundaries.

• Korean Journal of Community Nutrition
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• v.29 no.4
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• pp.318-335
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• 2024

Objectives: Despite the growing market share of online grocery shopping, there is a need to understand customer perceived value due to the ongoing advancements in information technology. This study explores the connections between attributes, consequences, and values. Additionally, it conducts a cross-country comparison of consumers' online grocery shopping behaviors to gain a deeper understanding of consumer market segments and any potential variations among them. Methods: Data was collected through an online questionnaire survey conducted from May 1 to 15, 2024, targeting 400 consumers in Seoul, Korea, and Shanghai, China, who have experience with online grocery shopping. The survey utilized the Means-End Chain theory and association pattern technique hard laddering. Data collation and analysis were conducted using the IBM SPSS Statistics 28.0 program. The LadderUX software was employed to analyze the links between attributes, consequences, and values and create the consumer purchasing process's implication matrix and hierarchical value map (HVM). Results: The study identified key attributes that influence online grocery shopping decisions, including delivery service, price, freshness, and quality. Korean consumers demonstrated a higher sensitivity to price (19.0%) and delivery service (17.0%). In contrast, Chinese consumers prioritized delivery service (15.0%) and after-sales service (14.8%). Commonly cited consequences included time saving (12.6% for Koreans, 11.3% for Chinese), whereas prevalent values encompassed convenience (36.8% for Koreans, 19.6% for Chinese) and economic value (26.6% for Koreans, 14.7% for Chinese). The HVM underscored these insights, highlighting diverse consumer preferences and country-specific nuances. Conclusions: The findings highlight the current state of online food consumption and consumers' value systems, revealing variations among countries. These findings offer empirical insights that can be used to create customized global marketing strategies that resonate with various consumer preferences and market dynamics.

• Journal of Microbiology and Biotechnology
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• v.34 no.9
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• pp.1810-1818
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• 2024

Autophagy is essential for regulating hair growth. Accordingly, we developed autophagy activator ICP5249 (pentasodium tetracarboxymethyl palmitoyl dipeptide) and investigated its potential role in hair growth. We evaluated its effect on hair growth using in vitro human dermal papilla cells (hDPCs) culture model, human hair follicles (hHFs) organ culture model, and telogenic mouse model. ICP5249 increased hDPCs proliferation and alkaline phosphatase (ALP) expression. It also increased microtubule-associated protein (MAP) light chain 3-II (LC3-II) expression and AMP-activated protein kinase α (AMPKα) and unc-51-like kinase 1 (ULK1) phosphorylation in hDPCs. ICP5249 extended the length of hHFs and increased LC3-II please revised from LC3 II to LC3-II in all manuscript expression. Consistently, ICP5249 also significantly increased hair growth area, dermis thickness, and anagen and telogen ratio in telogenic mice. Furthermore, it upregulated Ki-67 and LC3-II expression and AMPKα phosphorylation on the mice's dorsal skin. To investigate whether AMPK regulates ICP5249-induced hair growth, following treatment with the compound C, AMPK inhibitor, the activity of ICP5249 was evaluated. The effects of ICP5249 on hair growth were assessed following pretreatment with the AMPK inhibitor compound C. The results showed that compound C suppressed ICP5249-mediated proliferation and hair inductivity in hDPCs. Additionally, compound C inhibited ICP5249-mediated hair growth area, dermis thickness, anagen and telogen ration, and LC3-II expression in mice, suggesting that ICP5249 promotes hair growth by modulating autophagy, with AMPKα playing a regulatory role in this process. Taken together, we demonstrate that ICP5249 has the potential as an ingredient for improving hair growth.

• Journal of the Society of Naval Architects of Korea
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• v.61 no.5
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• pp.324-333
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• 2024

This paper focuses on the cooperation between Unmanned Aerial Vehicle (UAV) and Unmanned Surface Vessel (USV). It aims to develop efficient guidance and control algorithms for USV based on obstacle identification and path planning from aerial images captured by UAV. Various obstacle scenarios were implemented using the Robot Operating System (ROS) and the Gazebo simulation environment. The aerial images transmitted in real-time from UAV to USV are processed using the computer vision-based deep learning model, You Only Look Once (YOLO), to classify and recognize elements such as the water surface, obstacles, and ships. The recognized data is used to create a two-dimensional grid map. Algorithms such as A^* and Rapidly-exploring Random Tree star (RRT^*) were used for path planning. This process enhances the guidance and control strategies within the UAV-USV collaborative system, especially improving the navigational capabilities of the USV in complex and dynamic environments. This research offers significant insights into obstacle avoidance and path planning in maritime environments and proposes new directions for the integrated operation of UAV and USV.

• The Korean Journal of Archival Studies
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• no.13
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• pp.179-203
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• 2006

This study develops the process and method of official administration documents which have remained ill-balanced like the official documents of the government-general of Chosun(the pro-Japanese colonial government (1910-1945)). At first, the existing Appraisal-theories are recomposed. The Appraisal-Theories of Schellenberg is focused valuation about value of records itself, but fuction-Appraisal theory is attached importance to operational activities which take the record into action. But given that the record is a re-presentation of operational activities, the both are the same on the philosophy aspect. Therefore, in the case that the process - method is properly designed, it can be possible to use a composite type between operational activities and records. Also, a method of the Curve has its strong points in the macro and balanced aspect while the Absolute has it's strength in the micro aspect, so that chances are that both alternate methodologies are applied to the study. Hereby, the existing Appraisal theories are concluded to be the mutually-complemented things that can be easily put together into various forms according to the characteristics of an object and its situation, in the terms of the specific Appraisal methodology. Especially, in the case of this article dealing with the imbalance remains official-documents, it is necessary to compromise more properly process with a indicated useful method than establishing a method and process by choosing the only one theory. In order to appraise the official-documents of the pro-Japanese colonial government (1910-1945), a macro appraisal of value has to be appraised about them by understanding a system, functions and using the historical-cultural evolution, after analysing Disposal Authority. From this, map the record so that organization function maps are constructed regarding the value rank of functions and detailed-functions. After this, establish the appraisal strategy considering the internal environment of archival agencies and based on micro appraisal to a great quantity of records remained and supplying other meaning to a small quantity of records remained for example, the oral resources production are accomplished. The study has not yet reached the following aspects ; a function analysis, historical decoding techniques, a curve valuation of the record, the official gazette of the government general of Chosun( the pro-Japanese government for 1910-1945), an analysis method of the other historical materials and it's process, presentation of appraisal output image. As the result, that's just simply a proposal and we should fill in the above-mentioned shortages of the study through development of all the up-coming studies.

• Journal of the Korean Institute of Traditional Landscape Architecture
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• v.33 no.4
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• pp.38-51
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• 2015

In the maps of the period, there were three large ponds called Dongji(東池), Seoji(西池) and Namji(南池) in Hanyang, the capital of Joseon Dynasty. They were different than the ponds found in the palace, civic buildings, and private dwellings. Dongji, Seoji and Namji were ponds relating to Fortress wall of Seoul, and all had lotuses cultivated in them. The purpose of this paper is to clarify the locational and spatial characteristics of these ponds and to detail the construction and reconstruction process and management conditions through maps, drawings, illustrations, historical records and literary works from the urban environmental perspective. The results are as follows. First, Seoji and Namji were intended for Bibo(裨補) which redeemed the geographical weaknesses of Hanyang, securement of bright court water(明堂水), supplement for fire energy(火氣), fire preventive water and waterscape facilities, while Dongji was emphasized on protecting water mouth(水口) besides Bibo and securement of bright court water. Second, Seoji was connected to mountain streams and Dongji and Namji were to ditches. The ponds connected to ditches had been difficult to fill and maintain. Third, Seoji and Namji were in urban areas, whereas Dongji was in farmlands, and these locational differences had an influence on the use of ponds. Fourth, the shapes of ponds, in contrast to the ponds in palace and civic buildings, which were perfectly square, were either freeform or square with rounded edges. Fifth, lotus ponds could be maintained by continuous management polices, earth filling and reconstructing process were repeated during the Joseon Dynasty. The lotus ponds of Fortress Wall of Seoul which had managed over 500 years, were built in, in accordance with the tenets of Bibo pungsu geomancy; however as time passed, they were maintained not only as public open spaces, but also a cultural attraction for residents and visitors.

• Development and Reproduction
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• v.12 no.1
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• pp.87-95
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• 2008

Neural stem/precursor derived from pluripotent human embryonic stem cells (hESCs) has considerable therapeutic potential due to their ability to generate various neural cells which can be used in cell-replacement therapies for neurodegenerative diseases. However, production of neural cells from hESCs remains technically very difficult. Understanding neural-tube like rosette characteristic neural precursor cells from hESCs may provide useful information to increase the efficiency of hESC neural differentiation. Generally, neural rosettes were derived from differentiating hEBs in attached culture system, however this is time-consuming and complicated. Here, we examined if neural rosettes could be formed in suspension culture system by bypassing attachment requirement. First, we tested whether the size of hESC clumps affected the formation of human embryonic bodies (hEBs) and neural differentiation. We confirmed that hEBs derived from $500{\times}500\;{\mu}m$ square sized hESC clumps were effectively differentiated into neural lineage than those of the other sizes. To induce the rosette formation, regular size hEBs were derived by incubation of hESC clumps($500{\times}500\;{\mu}m$) in EB medium for 1 wk in a suspended condition on low attachment culture dish and further incubated for additional $1{\sim}2$ wks in neuroectodermal sphere(NES)-culture medium. We observed the neural tube-like rosette structure from hEBs after $7{\sim}10$ days of differentiation. Their identity as a neural precursor cells was assessed by measuring their expressions of neural precursor markers(Vimentin, Nestin, MSI1, MSI2, Prominin-1, Pax6, Sox1, N-cadherin, Otx2, and Tuj1) by RT-PCR and immunofluorescence staining. We also confirmed that neural rosettes could be terminally differentiated into mature neural cell types by additional incubation for $2{\sim}6$ wks with NES medium without growth factors. Neuronal(Tuj1, MAP2, GABA) and glial($S100{\beta}$ and GFAP) markers were highly expressed after $2{\sim}3$ and 4 wks of incubation, respectively. Expression of oligodendrocyte markers O1 and CNPase was significantly increased after $5{\sim}6$ wks of incubation. Our results demonstrate that rosette forming neural precursor cells could be successfully derived from suspension culture system and that will not only help us understand the neural differentiation process of hESCs but also simplify the derivation process of neural precursors from hESCs.

• Journal of the Korean Society of Earth Science Education
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• v.10 no.3
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• pp.308-322
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• 2017

It is the purpose of the study to investigate how high school students understand the concept of carbon cycle according to their spatial perception ability. For this, a total of 30 male students and 33 female students, who belong to the science course of the 2nd grade at a general co-education high school located in a megalopolis of Korea and have finished the class of Earth Science I in the first semester, took part in the spatial perception ability test, and four male students and four female students were selected as members of two groups : one group of higher spatial perception ability and the other group of lower spatial perception ability, and they agreed to participate in the study and have got the test of the carbon cycle concept. The results are as followings. It was found that the students who had higher spatial perception ability recorded more scores in the carbon cycle concept, state change concept, and process concept at the factor of word association and the carbon cycle concept, state change and process concept at the factor of drawing than those who had lower spatial perception ability. Connecting link used in the systemic viewpoint was disclosed like this in the factor of causal map of those who had higher spatial perception ability : one student 2 and another one student 1 and the other two students 0 : and in the factor of drawing three students 1 and the other 0 ; But nothing was found in the factors of causal map and drawing of those who had lower spatial perception ability. In addition, it was also found that those students who had higher spatial perception ability, when compared with those students who had lower spatial perception ability, have understood the fact that carbon moves through the interaction of the earth system's lower parts; Three students, who showed higher spatial perception ability, had a low level of systemic thinking concept, and one student who had higher spatial perception ability and four students who had lower spatial perception ability did not have a systemic thinking concept.

• Journal of the Korean Association of Geographic Information Studies
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• v.21 no.4
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• pp.175-190
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• 2018

Recently, policy of the marine advanced countries were switched from the preemption using ocean to post-project development. In this study, we suggest improvement and the pending issues when are deducted to the database of the marine spatial information is constructed over the GIS system for the Korean Marine Spatial Planning (KMSP). More than 250 spatial information in the seas of Korea were processed in order of data collection, GIS transformation, data analysis and processing, data grouping, and space mapping. It's process had some problem occurred to error of coordinate system, digitizing process for lack of the spatial information, performed by overlapping for the original marine spatial information, and so on. Moreover, solution is needed to data processing methods excluding personal information which is necessary when produce the spatial data for analysis of the used marine status and minimized method for different between the spatial information based GIS system and the based real information. Therefore, collection and securing system of lacking marine spatial information is enhanced for marine spatial planning. it is necessary to link and expand marine fisheries survey system. It is needed to the marine spatial planning. The marine spatial planning is required to the evaluation index of marine spatial and detailed marine spatial map. In addition, Marine spatial planning is needed to standard guideline and system of quality management. This standard guideline generate to phase for production, processing, analysis, and utilization. Also, the quality management system improve for the information quality of marine spatial information. Finally, we suggest necessity need for the depths study which is considered as opening extension of the marine spatial information and deduction on application model.