• Structural Engineering and Mechanics
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• v.86 no.1
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• pp.93-107
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• 2023

In this paper, a density based topology optimization is proposed for generating of supports required in additive manufacturing to maintain the overhanging regions of main structures during layer by layer fabrication process. For this purpose, isogeometric analysis method is employed to model geometry and structural analysis of main and support structures. In order to model the problem two cases are investigated. In the first case, design domain of supports can easily be separated from the main structure by using distinct isogeometric patches. The second case happens when the main structure itself is optimized by using topology optimization and the supports should be designed in the voids of optimum layout. In this case, in order to avoid boundary identification and re-meshing process for separating design domain of supports from main structure, a parameterization technique is proposed to identify the design domain of supports. To achieve this, two density functions are defined over the entire domain to describe the main structure and supporting areas. On the other hand, since supports are under gravity loads while main structure and its stiffness is not completed during manufacturing process, in the proposed method, stiffness of the main structure is considered to be trivial and the gravity loads are also naturally applied to design support structures. By doing so, the results show reasonable supports are created to protect, continuously, overhanging surfaces of the main structure. Several examples are presented to demonstrate the efficiency of the proposed method and compare the results with literature.

• The Bulletin of The Korean Astronomical Society
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• v.44 no.2
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• pp.63.3-63.3
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• 2019

Nearby young moving groups (NYMGs hereafter) are gravitationally unbound loose young stellar associations located within 100 pc of the Sun. Since NYMGs are crucial laboratories for studying low-mass stars and planets, intensive searches for NYMG members have been performed. For identification of NYMG members, various strategies and methods have been applied. As a result, the reliability of the members in terms of membership is not uniform, which means that a careful membership re-assessment is required. In this study, I developed a NYMG membership probability calculation tool based on Bayesian inference (Bayesian Assessment of Moving Groups: BAMG). For the development of the BAMG tool, I constructed ellipsoidal models for nine NYMGs via iterative and self-consistent processes. Using BAMG, memberships of claimed members in the literature (N~2000) were evaluated, and 35 per cent of members were confirmed as bona fide members of NYMGs. Based on the deficiency of low-mass members appeared in mass function using these bona fide members, low mass members from Gaia DR2 are identified. About 2000 new M dwarf and brown dwarf candidate members were identified. Memberships of ~70 members with RV from Gaia were confirmed, and the additional ~20 members were confirmed via spectroscopic observation. Not relying on previous knowledge about the existence of nine NYMGs, unsupervised machine learning analyses were applied to NYMG members. K-means and Agglomerative Clustering algorithms result in similar trends of grouping. As a result, six previously known groups (TWA, beta-Pic, Carina, Argus, AB Doradus, and Volans-Carina) were rediscovered. Three the other known groups are recognized as well; however, they are combined into two new separate groups (ThOr+Columba and TucHor+Columba).

• Proceedings of the Korean Society of Crop Science Conference
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• 2020.06a
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• pp.120-120
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• 2020

Based on the simple sequence repeat (SSR) marker, a Korean wheat core collection were established with 616 wheat accessions. Among them, the SNP genotyping for the entire genome was performed using DNA chip array to clarify the whole genome SNP profiles. Consequently, a total of 35,143 SNPs were found and we re-established a mini-core collection with 247 accessions. Population diversity and phylogenetic analysis revealed genetic diversity and relationships from the mini core set. In addition, genome-wide association study (GWAS) was performed on 19 phenotypic traits; ear type, awn length, culm length, ear length, awn color, seed coat color, culm color, ear color, loading, leaf length, leaf width, seeding stand, cold damage, weight, auricle, plant type, heading stage, maturation period, upright habit, and degree of flag leaf. The GWAS was performed using the fixed and random model circulating probability unification (FarmCPU), which identified 14 to 258 SNP loci related to 19 phenotypic traits. Our study indicates that this Korean wheat mini-core collection is a set of germplasm useful for basic and applied research with the aim of understanding and exploiting the genetic diversity of Korean wheat varieties.

• International conference on construction engineering and project management
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• 2011.02a
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• pp.221-228
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• 2011

As construction works have become larger and more complex, improving productivity by introducing Information Technology (IT) is pursued and more effective construction management is needed in construction industry. In this circumstance, many different kinds of project management system is being introduced, and various IT technologies are applied such as Personal Digital Assistant (PDA), Bar Code, Radio Frequency Identification (RFID), Web Camera, and so on. However, these kinds of technologies might cause re-processing of information and ineffectiveness of project because of lack of real time information processing technology or separation between construction sites and management offices. Meanwhile, these technologies rather decrease the construction productivity except for the data saving and database function. Therefore, this research aims to develop Application that can be applied efficiently for construction material management, by understanding problems of former management system with questionnaires and extracting functions with analysis of requirements. In virtue of the construction material management Application which will be developed in this study, it will be possible to input information automatically, to process and check material information in real time, and to identify the location of necessary material. Then, the problem of separation between construction sites and management offices are solved, and as a result, more efficient management of materials in construction sites will become possible. At the same time, this study will investigate the possibility and applicability of new IT device, Smart Phone to construction sites.

• Research in Plant Disease
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• v.30 no.1
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• pp.95-98
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• 2024

In a survey conducted in March 2023, Euphorbia hypogaea plants cultivated within greenhouses in Yongin, Korea exhibited water-soaked areas near the stem base, close to the soil. Subsequent isolation from diseased E. hypogaea led to the identification of a bacterial strain, designated as CBNUMPBL-103. The isolate was identified as Dickeya dadantii through sequencing of the 16s rRNA and phylogenetic analysis. The pathogenicity of the isolate was confirmed by inoculating it into healthy E. hypogaea, resulting in the manifestation of similar symptoms observed during the survey. The re-isolated strain recovered from inoculated plants showed a similar morphology with the inoculated strain. This is the first documentation of D. dadantii causing soft rot of E. hypogaea in Korea.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.18 no.6A
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• pp.63-73
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• 2008

RFID(Radio Frequency IDentification) system is an automated identification system that basically consists of tags and readers and Back-End-Databases. Tags and Readers communicate with each other by RF signal. As a reader can identify many tags in contactless manner using RF signal, RFID system is expected to do a new technology to replace a bar-code system in supply-chain management and payment system and access control and medical record and so on. However, RFID system creates new threats to the security of systems and privacy of individuals, Because tags and readers communicate with each other in insecure channel using RF signal. So many people are trying to study various manners to solve these problems against attacks, But they are difficult to apply to RFID system based on EPCglobal UHF Class-1 Generation-2 tags. Recently, Chien and Chen proposed a mutual Authentication protocol for RFID conforming to EPCglobal UHF Class-1 Generation-2 tags. we discover vulnerabilities of security and inefficiency about their protocol. Therefore, We analyze vulnerabilities of their protocol and propose an efficient mutual authentication protocol that improves security and efficiency.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.34 no.1
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• pp.74-84
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• 1998

A doubly resonant ultrasonic transducer has been designed as an attempt to increase the bandwidth of underwater transducers. The dual resonance conditions were accomplished by attaching a single acoustic matching layer on the front face of a Tonpilz transducer consisted of an aluminum head, a piezoelectric ring, a brass tail and a prestress bolt. A modified Mason's model was used for the performance analysis and the design of transducers, and the constructed transducers were tested experimentally and numerically by changing the impedances and thicknesses of the head, tail and matching layers in the water tank. Two distinct resonance peaks in the transmitting voltage response(TVR) of a developed transducer were observed at 34.3 and 40.4 kHz, respectively, with the difference frequency of 6.1kHz and the center frequency of 37.2kHz. The values of TVR at these frequencies were 136.5 dB re $1\;\muPa/V$ at 34.3 kHz and 136.8 dB re $1\;\muPa/V$ at 40.4 kHz, respectively. Reasonable agreement between the experimental results and the numerical results was achieved. From this result, it is expected that the generation of the distinct resonances at any two desired frequencies can be achieved through the proper choice of the matching layer to provide the impedance transformation between the transducer and the medium.

• Research in Plant Disease
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• v.12 no.3
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• pp.168-177
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• 2006

Thirty-nine strains of Colletotrichum gloeosporioides and 5 strains of C. acutatum stored in Korean Agricultural Culture Collection(KACC) were re-identified based on molecular characteristics of ribosomal internal transcribed spacer(ITS) and partial $\beta$-tubulin gene and cultural characteristics on potato dextrose agar(PDA) and Benomyl-added PDA. As the results, 19 strains were identified as C. acutatum with 13 strains of group A2, 5 strains of group A3, and 1 strain of group A4. In addition, 20 strains were identified as C. gloeosporioides with 18 strains of ribosomal DNA group(RG) 4 and 2 strains of RG6. The rest were identified as C. boninense RG5(2 strains), C. coccodes RG2(2 strains), and C. dematium RG12(1 strain). Out of domestic 31 strains, 12 strains were identified as C. acutatum A2, one strain as C. acutatum A3, 14 strains as C. gloeosporioides RG4, 2 strains as C. gloeosporioides RG6, one strains as C. boninense RG5 and one strain as C. dematium RG12. We also discussed taxonomy of C. gloeosporioides and C. acutatum and composition of C. gloeosporioides/C. acutatum isolates from major crops in Korea.

• Korean Journal of Microbiology
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• v.46 no.2
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• pp.152-156
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• 2010

Disposable contact lenses, which are one type of soft contact lenses, provide convenience in use, but also cause various ocular infectious diseases. Microorganisms that cause eye diseases include Acanthamoeba, bacteria, Fungi, and so on. It is impossible to prevent microorganism contamination completely due to the use of hands as wearing contact lenses. The contamination by various microorganisms leads to infectious keratitis, but it is not well known for the exact microorganisms that affect the disease. For this reason, to identify the microorganisms, two groups that are commonly used for disinfection of lenses were divided: normal saline solution and multiple purpose solution. Using these solutions the degree of microorganism contamination was observed according to the days of 1, 3, 5, 10, and 15. Twenty students by two groups from Ophthalmic Optics department at D college in Daegu Metropolitan city participated in the experiment after their ocular health conditions were checked. During they wore one-day disposable lenses for 1, 3, 5, 10, and 15 days, bacteria were cultured in media. The results, which were Gram stained by selecting the cultured colonies, show as followings: Gram positive cocci 33%, Gram-negative cocci 2%, Gram positive bacilli 34%, and the Gram negative bacilli 31%, respectively. As for the identification of potential pathogens, VITEK system and API kit methods were used. Keratitis caused by bacteria known as Staphylococcus aureus, Pseudomonas aeruginosa were detected as a result of wearing contact lenses. This study examined the distribution of bacteria as wearing one-day disposable contact lenses and pathogenic bacteria according to the duration of wearing them. In conclusion, the importance of hygiene when using contact lenses is suggested.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.42 no.3
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• pp.247-255
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• 2016

In order to select a strain that forms a Biocellulose (BC), strain producing acetic acid was selected from commercially available kombucha. Through SM broth it was confirmed that the strain is a gram negative bacteria in the form of rods having no motility through a phase contrast microscope. The result of phylogenetic inference analysis based on 16S rDNA sequence analysis for the identification of strains was most closely related to Gluconobacter uchimurae (G. uchimurae) and was named G. uchimurae GYS15 strain. The strain showed the highest degree of growth when cultured for 14 days under the conditions of pH 5 and $25^{\circ}C$. Moreover, it showed the highest degree of growth in a Glucose addition disaccharide as the optimum carbon source sucrose and fructose. Also, 0.5% NaCl, upon the addition of Malto extract, showed the highest degree of growth. Based on investigation by the optimum growth conditions to confirm the physical properties of BC obtained by culturing G. uchimurae GYS15 strains. The surface structure was observed through an scanning electron microscope (SEM) showed a high networks structure. It until $8.6{\pm}0.38$ times when the water holding capacity is re-absorbed and re-absorbed holding oil up to $6.6{\pm}0.51$ times confirmed. In conclusion, using these material properties, it was possible to confirm the possibility of a variety of cosmetic materials and mask pack materials.