적층을 통한 금속조형 표현 연구

주동현,차경철 사단법인 한국조형디자인협회 2022 조형디자인연구 Vol.25 No.1

Crafts are losing the fields of production and technology that have been preserved in history due to the rapid development and spread of 3D printers in recent years. About 100 years ago, Walter Benjamin, worried that art would lose its role due to the development of reproduction technology, as in the present situation, argued that the value of art should be preserved through the restoration of the aura. What is the aura of art that Benjamin said, and how can it be applied to crafts to solve the problems of the present age? Crafts are like humans. Unlike replicas, there is direct communication with the material, and although it is cumbersome, there is directness in making it directly using tools. In addition, although the machine's operating time evaporates and disappears as time for production, the process of production in crafts has historical significance as a process of continuous dialogue between materials, works, and artists. As a craftsman, I would like to reinterpret the process of 3D printers to prove that crafts are different from replicas. Similar to how 3D printers create shapes through lamination, the process of creating shapes by stacking layers through metal is studied as follows. first. A study on techniques and concepts of crafts using lamination second. Comparison between mechanical lamination and craft lamination third. A study on the possibility of lamination using welding fourth. Production of modeling works through lamination of welding Through a series of processes, one can understand the concept of lamination and study new methods of expression of metal molding to find the possibility of craft in the rapidly changing society and flow of modern art. Through this study, I tried to find the identity of craft by reinterpreting the process of 3D printer (FDM) in a craft. Its beginning was a study on the direction of craft in the rapid development of cloning technology and manufacturing technology. The craftsmanship and aura of crafts, in contrast to machine production and reproduction, are the human qualities of crafts and the identity of crafts that most closely interacts with humans. If we do not establish the identity of crafts corresponding to the rapidly changing times, we will be eroded by the reproduction technology. In order for our crafts to coexist with technology and tools, we must first establish the craftsmanship and identity of crafts. 공예는 최근 급격화된 3D프린터의 발달과 보급으로 역사에서 지켜오던 제작과 기술의 영역을 잃어가고 있다. 약 100여 년 전, 현 상황과 마찬가지로 복제 기술의 발달로 예술이 역할을 잃어버릴 것을 걱정한 발터 벤야민은 아우라의 회복을 통해 예술의 가치를 지켜야 한다고 주장했다. 벤야민이 말한 예술의 아우라란 무엇이며 그것을 공예에 적용하면 현 시대의 문제를 어떻게 해결할 수 있을까. 공예는 인간과 닮아 있다. 복제품과는 다르게 재료와의 직접적인 교감이 있으며 번거롭지만 도구를 사용해 직접 제작하는 직접성이 있다. 또 기계적 적층에서 각 층은 형태를 이루기 위한 요소이자 기계가 가동된 물리적 시간의 경과를 나타내지만, 공예에서 쌓인 각 층은 제작의 과정으로써 재료와 작품, 작가의 끊임없는 대화의 과정을 드러내며 역사성을 지닌다. 기계생산품 및 복제품과는 차별되는 공예작품에 대해 증명하기 위해 3D프린터와 같은 과정을 공예가로서 재해석하고자 한다. 3D프린터가 적층을 통해 형태를 만드는 과정과 마찬가지로 금속을 통해 층을 쌓아 형태를 만드는 과정을 다음과 같이 연구한다. 첫째. 적층을 활용한 공예의 기법 및 개념에 대한 연구둘째. 기계적 적층과 공예적 적층의 비교셋째. 용접을 활용한 적층의 가능성 연구넷째. 용접의 적층을 통한 조형 작품 제작일련의 과정을 통해 적층의 개념을 이해하고, 새로운 금속조형 표현 방법을 연구하여 급변하는 사회와 현대미술의 흐름 속에서 공예의 새로운 가능성을 찾을 수 있다. 이번 연구를 통해 3D프린터의 과정(FDM)을 공예적으로 재해석하여 수공의 가치와 공예의 정체성을 찾고자 했다. 그 시작은 복제 기술과 제작기술의 급속한 발전 속에서 공예의 방향성에 대한 고찰이었다. 기계 생산 및 복제와 대비되는 공예의 공예다움과 아우라는 곧 공예의 인간다움이며 인간과 가장 밀접하게 만나는 공예의 정체성이다. 급변하는 시대와 상응하는 공예의 정체성을 우리 스스로 확립하지 않으면 복제 기술에 침식될 것이다. 우리 공예는 기술과 도구와 공생하기 위해 우선적으로 공예다움과 공예의 정체성을 확립해야 한다.

Chest CT scan as an initial diagnostic method for tuberculosis infection detected by mass screening in the intermediate-burden country

주동현,허은영,김덕겸,정희순,이정규 대한결핵 및 호흡기학회 2018 대한결핵 및 호흡기학회 추계학술대회 초록집 Vol.126 No.-

Background: The first step in diagnosing latent tuberculosis (TB) in patients with confirmed TB infection is to exclude active TB. The currently recommended test for this is chest X-ray (CXR), with limited data on whether computed tomography (CT) can be a better alternative. We aimed to elucidate a diagnostic yield of CT as an initial diagnostic method for patients with TB infection confirmed by mass screening in a country with intermediate burden of TB. Methods: A retrospective study was conducted on patients who were identified as TB infection with tests conducted as a part of mass screening test in South Korea from January 2015 to March 2018. They were classified according to whether they had a CXR or CT as an initial diagnostic test to exclude TB. Detection rate of active TB and implementation rate of further procedures were compared between each group. Results: Of 542 patients with TB infection confirmed by mass screening, 222 and 320 patients were initially examined by a CXR and CT, respectively. The detection rate of active TB was not different according to initial radiologic method (CXR vs. CT, 0.9% vs. 2.5%; P=0.300). However, bronchoscopy (CXR vs. CT, 1.4% vs. 6.6%; P=0.007) and TB PCR test (CXR vs. CT, 1.8% vs. 7.8%; P=0.004) were performed significantly more in CT group than CXR group. Conclusion: CT was not supported as an initial diagnostic method to rule out active TB in patients with TB infection confirmed by mass screening in an intermediate-burden country, because it didn’t show difference in detecting active TB despite increasing further invasive tests.

티타늄의 열처리 조건에 따른 동전위 양극분극특성 및 표면 미세구조 변화

주동현,이용렬,정영화,양홍서,박상원,이도재,송호준,박영준 대한치과재료학회 2002 대한치과재료학회지 Vol.29 No.2

Indirect lingual bracket set-up

주동현 대한치과기공학회 2002 대한치과기공학회지 Vol.24 No.1

F-68 Associations between exhaled volatile organic compounds (VOCs) and pulmonary function in chronic obstructive pulmonary disease (COPD)

주동현,윤호일,이상훈,이연주,박종선,조영재,이재호,이춘택 대한결핵 및 호흡기학회 2017 대한결핵 및 호흡기학회 추계학술대회 초록집 Vol.124 No.-

There has been need for novel biomarkers in chronic obstructive pulmonary disease (COPD) which can directly reflect airway inflammation and be used for risk stratification and phenotyping. Exhaled volatile organic compounds (VOCs) are promising non-invasive biomarkers. We conducted this study to identify exhaled VOCs associated with pulmonary function. 109 COPD patients were recruited in Seoul national university Bundang hospital. End-tidal exhalation flow of patients was collected in Tenaxⓡ absorption tube and analyzed with gas chromatography mass spectrometry (GC-MS) to identify VOCs. Association between VOCs and pulmonary function was analyzed with Pearson’s correlation analysis. Total 294 VOCs were detected and COPD-specific VOCs were analyzed. Acetone (107 of 109 subjects) showed positive correlation with forced expiratory volume in one second and peak expiratory flow (r=0.220 (p = 0.023) and r=0.215 (p=0.026), respectively). It also showed negative correlation with Residual volume (RV) and Residual volume over total lung capacity (RV/TLC) (r=-0.280 (p = 0.005) and -0.205 (p = 0.043), respectively). 3-hydroxy-2-butanone (32 of 109 subjects) showed positive correlation with RV, RV/TLC (r=0.498 (p = 0.006) and 0.623 (p < 0.005). It also showed negative correlation with forced volume capacity (r = -0.505, p = 0.003). We found VOCs that correlated with pulmonary function of COPD patients. These VOCs have potential to be used for early diagnosis, prediction of exacerbations. Additional study compared with controls and external validation with other cohorts are needed.

복합 생체 척도 거리를 이용한 사용자 인증시스템의 구현

주동현,김두영 한국융합신호처리학회 2002 융합신호처리학회 논문지 (JISPS) Vol.3 No.2

본 논문에서는 정확도 향상을 위해 다중 생체 인식정보와 비접촉 IC카드를 사용하는 사용자 인증시스템을 제안하였다. 다중 생체 인식정보는 안면영상, 홍채영상, 4-digit 음성암호로 구성하였으며, 비접촉 IC-Card는 사용자의 기본정보를 제공한다. 만약 사용자의 기본정보화 부합되는 표본화된 다중생체 인식정보와 현장에서 측정된 생체정보와의 거리가 threshold보다 작은경우에 본인으로 인증하였고, 그외의 경우에는 기각시키는 방식을 사용하였다 본 논문에서는 실험을 통해, 기존의 인식방식보다 사용자의 인증률이 개선됨을 보였다. In this paper we proposed the user identification system using hybrid biometric information and non-contact IC card to improve the accuracy of the system. The hybrid biometric information consists of the face image, the iris image, and the 4-digit voice password of user. And the non-contact IC card provides the base information of user If the distance between the sample hybrid biometric Information corresponding to the base information of user and the measured biometric information is less than the given threshold value, the identification is accepted. Otherwise it is rejected. Through the result of experimentation, this paper shows that the proposed method has better identification rate than the conventional identification method.

Nd:YAG Laser 직접 각인을 이용한 Carbon 스트레인 센서

주동현,윤상우,김주한,박우태,Joo, Donghyun,Yoon, Sangwoo,Kim, Joohan,Park, Woo-Tae 한국마이크로전자및패키징학회 2018 마이크로전자 및 패키징학회지 Vol.25 No.1

Nd:YAG Laser를 이용하여 polyimide film에 탄화(carbonization)를 진행하여 Carbon을 생성하여 저가의 센서를 간단한 제조과정으로 만들었다. 이를 통하여 유연한 저가형 압저항 센서의 특성에 관한 연구를 수행하였다. 기존에 많은 연구들이 Polyimide에 $10.6{\mu}m$의 파장을 가지는 $CO_2$ laser를 이용하여 carbonization을 하여 센서를 제작하였다. 본 논문에서는 polyimide film에 $1.064{\mu}m$의 파장을 가지는Nd:YAG laser를 이용하여 carbonization(탄화공정)을 진행하였다. 또한 Nd:YAG laser를 사용하여 polyimide film위에 직접 탄화시키며 carbon을 생성하는 최적의 전력밀도($W/cm^2$)과 속도(scan rate) 조건 조합을 찾아 해상도를 높였다. $CO_2$ laser를 사용하였던 기존의 선행연구에서는 carbon생성의 최소 선폭이 $140{\sim}220{\mu}m$의 길이를 가졌지만, 본 연구에서는 카본의 생성되는 선폭이 $35{\sim}40{\mu}m$으로 축소시켰다. 이번 연구에서 제작된 센서의 초기 면저항은 $100{\sim}300{\Omega}/{\square}$ 이였다. 곡률 반경 21 R 로 인장을 하였을 때 저항이 30% 줄어들었고, 이를 통하여 계산된 게이지 팩터는 56.6이였다. 본 연구는 압저항 센서를 제조하기 위한 단순하고, 매우 유연하고 저렴한 공정을 제공한다. Nd:YAG laser was used to carbonize polyimide films to produce carbon films. This is a simple manufacturing process to fabricate low cost sensors. By applying this method, we studied characteristics of flexible and low-cost piezoresistive. Previously, many studies focused on carbonization of polyimide using $CO_2$ laser with wavelength of $10.6{\mu}m$. In this paper, carbonization (carbonization process) was performed on polyimide films using an Nd:YAG laser with a wavelength of $1.064{\mu}m$. In order to increase the resolution, we optimized the laser conditions of the power density ($W/cm^2$) and the beam scan rate. In previous studies using $CO_2$ laser, the minimum line width was $140{\sim}220{\mu}m$ but in this study, carbon line width was reduced to $35{\sim}40{\mu}m$. The initial sheet resistance of the carbon sensor was $100{\sim}300{\Omega}/{\square}$. The resistance decreased by 30% under stretched with a curvature radius of 21 R. The calculated gauge factor was 56.6. This work offers a simple, highly flexible, and low-cost process to fabricate piezoresistive sensors.

타타늄의 열처리 조건에 따른 동전위 양극분극특성 및 표면 미세구조 변화

주동현,이용렬,정영화,양홍서,박상원,이도재,송호준,박영준 大韓齒科器材學會 2002 대한치과재료학회지 Vol.29 No.2

The corrosion resistance of metallic implants is essential for successful implant osseointegration. Moreover, the implant surface should have appropriate surface roughness for the attachment of the osteoblast and collagen fibrils. When titanium is exposed to air a thermodynamically very stable oxide film is formed at once. This oxide is very thin and yet it protects the metal from corrosion instantaneously. However, the oxide would not be ideal, and it would be supposed that the state of oxide film would be various by the different conditions when it is formed. The objective of this study was to evaluate the electrochemical properties and surface microstructural changes of titanium after passivation treatment or exposure to high heat (in vacuum or in air). ASTM grade 2 commercially pure titanium (Ti) disks of 10㎜ diameter were wet ground and polished with 240 and 600 grit SiC, and then ultrasonically cleaned with distilled water and ethanol. Cleansed as-received samples (As-R group) were passivated with 30% nitric acid solution at 50℃ for 15 minutes to make the Pas group. The Std-V samples were made by treating the Ti disks in vacuum quartz tube (10^-8 Torr) at 530℃ for 40 min for stress relieving, followed by annealing at 700℃ for 90 min, and then slow cooling to room temperature. The Std-A samples undergo identical procedure as the Std-V group except that it is done in air. For 530℃-V samples, Ti disks were heated at 530℃ for 40 minutes and slow cooled to room temperature. The 1000℃-V samples were produced by heating Std-V specimens again at 1000℃ for 2 hr, followed by cooling to room temperature. 530℃-A and 1000℃-A samples were also prepared. Potentiodynamic anodic polarization measurement, SEM, AFM and XRD analysis were performed to evaluate the effects of the various treatments. The difference in the mean values of E_corr between groups showed statistically significant difference (P<0.05), but that of I_corr did not show significance (P>0.05). When Ti surface was passivated there was a shift of corrosion potential (E_corr) in the noble direction and a lower corrosion current density (I_corr) value. Std-A samples showed most noble E_corr value among the tested groups. 530℃-V samples showed more noble E-corr than other tested groups except Std-A group. 1000℃-V samples showed more noble E-corr than those of Std-V sample. In the case of Std-, 530℃- and 1000℃-groups, -A sub-groups showed better corrosion resistant characteristics than -V sub-groups in regard to E-corr and I_corr values. In the SEM observations, the surfaces of the As-R samples showed only scratch line on smooth surface. In Pas samples, thick oxide layer covered the surface under high magnification observation. 530℃-A samples were covered by oxide granules, and Std-A samples had 25~50 nm-thick acicular oxides. The 1000℃-A samples were covered by coarse oxide crystals with a granule diameter of 0.1~0.6 μm having a gross appearance of milky white color, which was identified by XRD as a rutile. On the other hand, 1000℃-V samples showed an Widmansta¨tten structrue of which the orientation of the lattice is formed along crystallographic planes of the parent crystals. On the AFM observation, 530℃-A samples showed RMS roughness of 79.38 nm which is 5 times rougher than those of the As-R samples. Std-A sample had a roughness of 330.47 nm which is about 20-times rougher than that of the As-R sample. 1000℃-A samples were covered by coarse granular oxides and the roughness were about 0.56 μm. Vacuum sub-group samples showed a more smooth surface than air sub-group samples, and the oxide film was more dense. Due to variability of the surface treatment and heat treatment conditions, the process of the oxide formation seems to be affected thereby making the corrosion properties and surface micro-morphology different. However, more various electrochemical analysis together with surface analysis, and an investigation for the effects of those on the osteoblast cell adhesion and calcium phosphate apposition are needed for the improvement of the osseointegration rates of the titanium implants.

Development of a flexible strain sensor based on CNT/Ecoflex composite using 50 um twilled mesh

주동현,강문석,박우태 대한기계학회 2022 대한기계학회 춘추학술대회 Vol.2022 No.5

분할 정렬 알고리즘의 개선을 통한 JPEG2000 정지영상 부호화에서의 압축 효율 개선

주동현,김두영,Ju Dong-hyun,Kim Doo-young 한국정보통신학회 2005 한국정보통신학회논문지 Vol.9 No.5

멀티 미디어 사용의 증가에 따라 정보화 사회에 있어 정지 영상 정보를 높은 압축율로 방대한 데이터를 얼마나 빠르게 에러없이 전송 또는 처리 하는가 하는 문제가 요구 되어지고 있다. 본 논문은 정지영상 인코딩 분야에서 다양한 기능과 압축 성능을 보이고 있는 JPEG2000 압축효율 향상을 위하여 저주파 대역에 대한 부호화를 제거하고, 중복비트 제거를 이용한 개선된 분할정렬 알고리즘을 이용하여 웨이블렛 계수를 줄이는 방법을 제안하였다. 실험결과, 제안한 방법을 통해 기존의 JPEG2000 표준보다 더 우수한 양질의 성능과 저 비트율을 확인할 수 있었다. With the increasing use of multimedia technologies, image compression requires higher performance as well as new functionality. Specially, in the specific area of still image encoding, a new standard, JPEG2000 was developed. This paper proposed Set Partitioning Sorting Algorithm that uses a method to optimized selection of threshold from feature of wavelet transform coefficients and to removes sign bit in LL area on JPEG2000. Experimental results show the proposed algorithm achieves more improved bit rate.