• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.4
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• pp.551-556
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• 2018

With the rise of the fourth industrial revolution, the importance of establishing R&D strategies to develop ICT technologies such as Big Data, Artificial Intelligence, Robots, the Internet of Objects, and 3D Printing is increasing. In this study, we analyzed the effects of the fourth industrial revolution on society and the present state of the national defense technology planning system, and proposed improvement measures for the utilization of the fourth industrial revolution in the defense industry from the perspective of defense R&D. The current defense R&D strategy focuses on securing the core technologies of each weapon system required by the military through research and development. Under the current system, the role of fourth industrial revolution technology will be confined to some of the weapons systems required by the military. In order to overcome this limitation, we propose a technology roadmap for the future weapons systems.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.11a
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• pp.346-346
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• 2007

압전세라믹 재료는 현재 압전 변압기, actuator, transducer, sensor, speaker 등에 광범위하게 이용이 되고 있다. 이 중에서 압전세라믹 소결체를 이용한 스피커의 제조는 가공이 까다롭고, 대형의 크기로 제작 시 소자가 깨지는 등의 많은 제약을 받고 있으며, 저음 특성이 떨어져 응용 범위가 한정되어 있다. 따라서 최근에는 이러한 단점을 극복하기 위하여 세라믹/고분자 복합체를 이용한 필름 스피커를 제작하고자 시도하고 있다. 이러한 세라믹/고분자 0-3형 압전 복합체를 이용할 경우, 제품의 경량화를 실현할 수 있고, 크기나 환경의 영향을 거의 받지 않으므로, 고기능성 스피커로의 응용에 적합할 것으로 보인다. 따라서 본 연구에서는 PZT계의 세라믹와 PVDF, PVDF-TrFE, Polyester, acrylic resin 등의 여러 고분자 물질과의 복합체를 제조하여 압전특성을 평가하였다. 본 실험은 먼저 $(Pb_{1-a-b}Ba_aCd_b)(Zr_xTi_{1-x})_{1-c-d}(Ni_{1/3}Nb_{2/3})_c(Zn_{1/3}Nb_{2/3})_dO_3$ (이하 PZT라 표기)의 최적화 조성을 선택하여, $1050^{\circ}C$에서 소결된 분말을 48시간 ball milling방법 로 약 $1{\mu}m$ 크기로 분쇄하였다. 고분자 물질들은 알맞은 용제들을 선택하여 녹였다. 그 다음 소결된 PZT분말과 고분자를 50:50, 60:40, 65:35, 70:30등의 무게 분율로 혼합하고, 분산제, 소포제 등을 첨가하여 3단 roll mill을 이용하여 충분히 분산시켜 페이스트 (Paste)를 제조하였다. 제조된 페이스트를 ITO가 코팅된 PET필름 위에 스크린 프린팅 법을 사용하여 인쇄하여 $120^{\circ}C$에서 5분간 건조하였다. 코팅된 복합체의 두께는 약 $80{\mu}m$ 정도로 측정되었다. Ag 페이스트를 이용한 상부 전극 형성에도 스크린 프린팅 법을 적용하였다. 이를 $120^{\circ}C$에서 4 kV/mm의 DC 전계로 분극 공정을 수행한 후 전기적 특성을 평가하였다. 유전특성을 조사하기 위해서 LCR meter (EDC-1620)를 사용하였고, 시편의 결정구조는 XRD (Rigaku; D/MAX-2500H)을 통해 분석하였으며, 전자현미경(SEM)을 이용하여 미세구조를 분석하였다. 압전 전하상수$(d_{33})$ 값은 APC 8000 모델을 이용하여 측정하였다. PZT의 혼합비가 증가할수록 비유전율 및 압전 전하 상수 등의 전기적 특성이 증가되었다. 또 여러 고분자 물질 중에서 PVDF-TrFE 수지가 가장 우수한 특성을 보였다. 이는 PVDF-TrFE 수지가 압전성을 나타내기 때문인 것으로 판단되었다.

• The Journal of Korean Academy of Prosthodontics
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• v.53 no.1
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• pp.19-25
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• 2015

Nowadays, CAD/CAM is broadly used in dentistry for inlays, crowns, implant abutments and its spectrum is expanding to complete dentures. Utilizing CAD/CAM to fabricate complete dentures is expected to decrease chair time and the number of visits, thus decreasing total fabrication time, expenses and errors caused during fabrication processes. One of the systems using CAD/CAM, DENTCA$^{TM}$ CAD/CAM denture (DENTCA Inc. Los Angeles, USA) scans edentulous impressions, designs dentures digitally, fabricates try-in dentures by 3D printing and converts them into final dentures. Patients can wear final dentures after only 2 - 3 visits with satisfying adaptation. This case report introduces a 71-year-old male patient who visited to consult remaking of existing old dentures. Residual teeth with bad prognosis and root remnants were extracted and the patient used reformed existing mandibular denture for 2 months. And then DENTCA system started. One-step border molding was done using conventional tray of adequate size provided by DENTCA system and wash impression was taken. Gothic arch tracing was completed based on the vertical dimension of existing dentures. Both maxillary and mandibular trays were placed to the resultant centric relation and bite registration was taken. Then DENTCA scanned the bite registration, arranged the teeth, completed the festooning and fabricated the try-in dentures by 3D printing. The try-in dentures were positioned, occlusal plane and occlusal relations were evaluated. The try-in dentures were converted to final dentures. To create bilateral balanced occlusion, occlusal adjustment was done after clinical remounting using facebow transfer. The result was satisfactory and it was confirmed by patient and operator.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.48 no.3
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• pp.7-11
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• 2011

In this paper, we proposed a simple and high-yield printing process for source and drain electrodes of organic thin film transistor (OTFT). The surface energy of PVP (poly 4-vinylphenol) gate dielectric was decreased from 56 $mJ/m^2$ to 45 $mJ/m^2$ by adding fluoride of 3000ppm into it. Meanwhile the surface energy of source and drain (S/D) electrodes area on the PVP was increased to 87 $mJ/m^2$ by treating the areas, which was patterned by photolithography, with oxygen plasma, maximizing the surface energy difference from the other areas. A conductive polymer, G-PEDOT:PSS, was deposited on the S/D electrode areas by brushing painting process. With such a simple process we could obtain a high yield of above 90 % in $16{\times}16$ arrays of OTFTs. The performance of OTFTs with the fluoride-added PVP was similar to that of OTFTs with the ordinary PVP without fluoride, generating the mobility of 0.1 $cm^2/V.sec$, which was sufficient enough to drive electrophoretic display (EPD) sheet. The EPD panel employing the OTFT-backpane successfully demonstrated to display some patterns on it.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.1 no.2
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• pp.181-191
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• 1991

The present study determined the overall noise level and the distribution of sound pressure level over audible frequency range of noise produced at various work sites. Work-related noise greater than 80dBA produced from 98 separate work sites at 37 manufacturing companies and machine shops were analysed for the overall sound level (dBA) and frequency distribution. In addition, to determine the possible hearing loss related to work site noise, a hearing test was also conducted on 1,374 workers in these work sites. The results of the study were as follows ; 1. Of the total 98 work sites, 57 work sites(58.2%) produced noise exceeding threshold limit value (${\geq}90dBA$) set by the Ministry 01 Labor. In terms of different manufacturing industries the proportion of work sites which exceeded 90dBA was the highest for the cut-stone products industry with 6/6 work sites and lowest for the commercial printing industry with 1/13 work sites. 2. The percentage of workers who were exposed to noise greater than 90dBA was 19.8% (1,040 workers) 01 the total 5,261 workers. In terms of different industries, cut-stone products industry had the most workers exposed to noise exceeding 90dBA with 82.8%, textile bleaching and dyeing industry was next at 30.6% followed by fabricated metal products industry with 27.9%, plastic products manufacturing industry had the lowest percentage of workers exposed to 90dBA exceeding noise with 4.5%. 3. There was a statistically significant correlation between the frequency of noise-induced hearing loss and the percentage of workers exposed to noise exceeding 90dBA (P<0.05). 4. The frequency analysis of noise produced at the 98 work sites revealed that 44 work sites (44.9%) had the maximum sound pressure level at high-frequencies greater than 2KHz. In addition, significantly higher sound pressure level was detected at the high-frequencies at 90dBA exceeding work sites as compared to below 90dBA work sites (P<0.01). 5. The differences in sound level meter's A-and C-weighted sound pressure levels were analysed by frequencies. Of the 28 work sites which showed 0-1 dB difference in the two weighted sound levels, 20 work sites (71.4%) had significantly higher sound pressure levels at high-frequencies greater than 2KHz (P<0.01). Furthermore, there was a tendency for higher sound pressure levels to occur in the high-frequency range as the differences in the two weighted sound levels decreased.

• Korean Journal of Construction Engineering and Management
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• v.23 no.3
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• pp.95-103
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• 2022

Recently, the fourth industrial revolution has a great influence on the development of many industries as well as the construction industry. Various technologies related to the industrial revolution 4.0, such as AI and big data, have gained much attention. However, little has been known about the importance and preparedness of stakeholders of the construction industry in Korea for the industry 4.0 technologies so far. This study revealed how the stakeholders perceive and prepare for industry 4.0 using a survey. In addition, collaboration potential score for each technology was calculated to find technologies with high potential for collaboration. Result is that the importance of the technologies was evaluated high in overall, but the preparedness and implementation in university education or business was evaluated low. Technologies with high potential for industry-university collaboration are AI/big data and 3D printing/3D scanning. This study can contribute to the training of industry 4.0 experts and improving preparedness, which would enable the innovation and application of industry 4.0 technologies in the construction industry.

• Journal of the Microelectronics and Packaging Society
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• v.31 no.3
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• pp.42-49
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• 2024

In the electromagnetic wave shielding material market, superior shielding performance in the high-frequency range, along with flexibility and durability, has emerged as critical requirements. The need for high-performance EMI (Electromagnetic Interference) films to address electromagnetic wave interference issues is growing, particularly in various industrial sectors such as smart electronic devices, automotive electronic systems, and communication equipment. In this study, a trimodal silver paste was developed and fabricated into an EMI film, with its performance evaluated. The developed silver paste, utilizing a modified epoxy binder, exhibited properties suitable for screen printing processes. The film demonstrated excellent shielding performance, with an average attenuation of -99 dB in the high-frequency range of the 5G spectrum (26.5 GHz to 40 GHz), and a shielding effectiveness of -90.3 dB at 33.6 GHz. Flexibility and durability tests showed that the film maintained its flexibility even at a curvature radius of 1 mm. In the bending cycle test, the resistance increased by approximately 25.5% from 0.51 Ω to 0.64 Ω after 10,000 cycles in the outer bending scenario, while in the inner bending scenario, the resistance decreased by about 3.6%, indicating reduced resistance to compressive stress.

• Industry Promotion Research
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• v.5 no.4
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• pp.1-13
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• 2020

Since the 4th industrial revolution was thrown into the world at the Davos World Economic Forum in January 2016, the world has been undergoing major social and economic changes. In this study, the direction of quality management in the 4th industrial revolution era was examined. First, in all the major countries the industrial structural changes and smart business models were confirmed due to the convergence of new ICT such as IoT, robotics, 3D printing, big data, and AI with the existing technologies and industries. Second, we found that although the core technology level of the 4th industrial revolution in Korea is not as good as that of advanced countries, we have been working on expanding smart production methods and creating new industries by utilizing new ICT. Finally, it was confirmed that quality management is a real-time implementation of new ICT that reflects the needs of the market in real time based on big data from the planning and design stage of products or services.

• Journal of Sericultural and Entomological Science
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• v.23 no.1
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• pp.56-64
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• 1981

The textile fabric contains the functions of sanitation, decoration, wearing style and washing in the practical use. Among various tetile fiber, silk has less utilities than synthetic fiber in practical use although silk has good benefits of the high quality of silk fabric. Thus no textile fiber, neither natural norsynthetic, has all the functions. In this sense, many compound fabrics have been improved to reveal various functions of fabric However, this has been disturbed with the problem of dyeing, expecially in the case of compound fabric of silk. The work is carried out to improve the dyeing method of compound fabric of polyester and silk. The results obtained are as follows: 1. In the dyeing of compound fabric(P/S fabric), azo dyes was more suitable than anthraquinone dyes. 2. According to the carrier, dyeing spot was appeared by the high concentration in bath. 3. Degree of dye fixation was decreased in dyeing of methylnaptharine carrier(D.N) and anion disperser(T.S). 4. The affinity of dye was suitable in the dyeing bath of azo dye, trichlorobenzene carrier and nonion disperser. 5. Dye fixation of silk side in compound fabric by acid dye showed higher in acid bath of dyeing. 6. In printing of silk and polyester compound fabric, it must be understood relationship among fibers, dyes, and steaming conditions.

• The korean journal of orthodontics
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• v.50 no.5
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• pp.346-355
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• 2020

The treatment of skeletal Class III malocclusion in adolescents is challenging. Maxillary protraction, particularly that using bone anchorage, has been proven to be an effective method for the stimulation of maxillary growth. However, the conventional procedure, which involves the surgical implantation of mini-plates, is traumatic and associated with a high risk. Three-dimensional (3D) digital technology offers the possibility of individualized treatment. Customized mini-plates can be designed according to the shape of the maxillary surface and the positions of the roots on cone-beam computed tomography scans; this reduces both the surgical risk and patient trauma. Here we report a case involving a 12-year-old adolescent girl with skeletal Class III malocclusion and midface deficiency that was treated in two phases. In phase 1, rapid maxillary expansion and protraction were performed using 3D-printed mini-plates for anchorage. The mini-plates exhibited better adaptation to the bone contour, and titanium screw implantation was safer because of the customized design. The orthopedic force applied to each mini-plate was approximately 400-500 g, and the plates remained stable during the maxillary protraction process, which exhibited efficacious orthopedic effects and significantly improved the facial profile and esthetics. In phase 2, fixed appliances were used for alignment and leveling of the maxillary and mandibular dentitions. The complete two-phase treatment lasted for 24 months. After 48 months of retention, the treatment outcomes remained stable.