• Journal of Welding and Joining
• /
• v.34 no.3
• /
• pp.61-68
• /
• 2016

Characteristics of dissimilar metal welds between alloy steel ASTM A387 Gr. 91 and carbon steel ASTM A516 Gr.70 made with Flux cored arc welding(FCAW) have been evaluated in terms of microstructure, mechanical strength, chemical analysis by EDS as well as corrosion test. Three heat inputs of 15.0, 22.5, 30.0kJ/cm were employed to make joints of dissimilar metals with E91T1-B9C wire. Post-weld heat treatment was carried out at $750^{\circ}C$ for 2.5 h. Based on microstructural examination, tempered martensite and lower bainite were formed in first layer of weld metal. The amount of tempered martensite was decreased and the amount of lower bainite was increased with increasing heat input and layer. Heat affected zone of alloy steel showed the highest hardness due to the formation of tempered Martensite and lower Bainite. Tensile strengths of dissimilar welds decreased with increasing heat inputs. Dissimilar welds seemed to have a good hot cracking resistance due to the low HCS index below 4. The salt spray test of dissimilar metals showed that the corrosion rate increased with increasing heat inputs due to the increase of the amount of lower Bainite.

• Current Photovoltaic Research
• /
• v.2 no.1
• /
• pp.1-7
• /
• 2014

We developed a method of growing thin Si film at $600^{\circ}C$ by hot wire CVD using a very thin large-grained poly-Si seed layer for thin-film Si solar cells. The seed layer was prepared by crystallizing an amorphous Si film by vapor-induced crystallization using $AlCl_3$ vapor. The average grain size of the p-type epitaxial Si layer was about $20{\mu}m$ and crystallographic defects in the epitaxial layer were mainly low-angle grain boundaries and coincident-site lattice boundaries, which are special boundaries with less electrical activity. Moreover, with a decreasing in-situ boron doping time, the mis-orientation angle between grain boundaries and in-grain defects in epitaxial Si decreased. Due to fewer defects, the epitaxial Si film was high quality evidenced from Raman and TEM analysis. The highest mobility of $360cm^2/V{\cdot}s$ was achieved by decreasing the in-situ boron doping time. The performance of our preliminary thin-film solar cells with a single-side HIT structure and $CoSi_2$ back contact was poor. However, the result showed that the epitaxial Si film has considerable potential for improved performance with a reduced boron doping concentration.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
• /
• v.18 no.9
• /
• pp.745-752
• /
• 2006

DOS and NaCl aerosol particles were used to determine collection efficiencies of a 2-stage electrostatic wet scrubber with respect to particle size. The DOS and NaCl aerosols have geometric mean diameters of 0.1-3.0 urn, geometric standard deviations of $1.1{\sim}1.8$ and total number concentrations of $450{\sim}2,400\;particles/cm^3$. The tested operating variables for the electrostatic wet scrubber included air velocity and water injection rate. It was shown from the experimental results that particle collection efficiencies increased in the submicron particle size range when different polarities were applied on the water nozzle and corona wire, respectively. This increase in the collection efficiency is attributed to strong electrostatic attraction between the negative water droplets and positive submicron particles. The collection efficiencies also increased when water injection rate was increased or air velocity was decreased. Meanwhile, the pressure drop across the wet scrubber decreased by 90% compared with the existing mechanical wet scrubber. Finally, ammonia gas was used to determine gas removal efficiencies. It was observed that the gas removal efficiencies increased when the air velocity was decreased or the water injection rate was increased.

• Journal of the Korean Society of Fisheries and Ocean Technology
• /
• v.44 no.3
• /
• pp.184-193
• /
• 2008

For environment-friendly fishery, the lead sinkers of octopus drift line were developed with the environmentfriendly sinker, and their characteristics and performance were investigated. To make the environmentfriendly sinker, the hydrate ceramic material was developed, and to increase the weight and strength, the iron power was added to it. The fishing hook was machine-made, and standardized, by using 60cm iron wire. For the manufacture of the sinker, the first, the mold was made, and then, hydrate ceramic material and water were quantitatively mixed. The mixture was poured into the mold prepared with a fishing hook already inserted, and had hardened for several hour, before it was taken out of the mold as a complete sinker. The sinkers were made in the 8 types ranging in weight from 150 to 500g, and their specific gravities were diverse from 2.871 to 6.637, which was 0.19 to 0.44 times lower than that of lead. The movement of the environment-friendly sinker by flume tank was possible in the weaker current speed than the similar lead sinker. In the coastal fishing grounds of Gangwon province, the comparison of catching efficiency was made between the improved fishing gears composed of the environment-friendly sinkers and artificial baits, and the current used fishing gears of lead sinkers and pig-fat baits. The result showed the tendency in which the improved fishing gears caught the bigger octopuses than the current used fishing gears. In the quantity and number of the fish catch per unit fishing gear, the improved fishing gear showed a little more catch than the current used fishing gear, regardless of the fishing area. However, the number of the improved fishing gears lost during fishing operation was similar to that of the current used fishing gears.

• Journal of Welding and Joining
• /
• v.33 no.4
• /
• pp.37-43
• /
• 2015

Characteristics of dissimilar metal welds between STS 316L and carbon steel ASTM A516 Gr.70 made with GTAW have been evaluated in terms of microstructure, ferrite content, chemical analysis, hardness and corrosion resistance. Three heat inputs of 9.00, 11.25, 13.00kJ/cm were employed to make joints of dissimilar metals with ER309 wire. Based on microstructural examination, the amount of vermicular type of ${\delta}$-ferrite was increased with increasing heat input due to the increase of Creq/Nieq in the second layer of welds. Based on the EDX analysis of weld metals, Cr and Ni content in the 2nd layer increased while those content in the first layer of welds decreased with heat inputs. Cellular solidification mode in the 1st layer and dendritic solidification mode in the 2nd layer due to different cooling rates were prevailed, respectively. Heat affected zone which formed hard microstructure showed higher hardness than the weld metal. The salt spray test of dissimilar metals weld joints showed that the carbon steel surfaces only corroded. The weight loss rate due to corrosion increased up to 100hours but it decreased above 100 hours. There was little difference in the weight loss caused by corrosion regardless of heat inputs.

• Journal of Chest Surgery
• /
• v.30 no.2
• /
• pp.219-225
• /
• 1997

Although most of the patients with endobronchial tuberculosis have some degree of bronchial stenosis, more aggressive treatment is needed to restore the patency of the involved tracheobronchial tree for some patients not responding well to antituberculous chemotherapy combined with steroids. In our first case, we reseated stenotic trachea in a 42 years old women who showe overgrowing granulation tissue through the modified Gianturco steno wire which was previously inserted and anastomosed end to end. Another case was a 37 years old male with left main bronchial rcstenosis complicate, $\boxUl$ after inserting a Strecker stent and sleeve left upper lobectomy was performed.

• 한국신재생에너지학회:학술대회논문집
• /
• 2011.05a
• /
• pp.74.1-74.1
• /
• 2011

탄소나노튜브는 높은 전기 전도성과 열 전도성을 가지며, 이러한 특성 때문에 21세기를 주도해 나갈 수 있는 차세대 첨단 소재로서 각광을 받고 있다. 또한 최근에는 나노공학기술의 발달로 인하여 획기적으로 높은 열전도도를 나타내는 다중벽 탄소나노튜브(Multi-walled Carbon Nanotubes, MWCNTs)의 대량 생산이 가능하게 되면서 다중벽 탄소나노튜브의 높은 열전도도 특성을 이용하여 탄소나노튜브를 기본 유체 및 기능성 유체에 안정하게 분산 시킨 후 이를 이용하고자 하는 연구가 활발히 진행되고 있으며, 탄소나노튜브를 유체에 안정하게 분산시키기 위한 방법으로는 기계적 분산법, 물리적 흡착에 의한 분산법, 화학적 개질에 의한 분산법이 있다. 따라서 본 연구에서는 이들 분산 방법과 탄소나노튜브 입자의 물성치에 따른 나노유체의 특성을 알아보기 위하여 나노유체의 열전도도와 점도 특성을 비교 분석하였다. 모든 물성치는 같지만 탄소나노튜브의 길이만 다른 두 종류의 다중벽 탄소나노튜브에 각각 계면 활성제(Sodium Dodecyl Sulfate, SDS) 100 wt%와 고분자 화합물(Polyvinyl Pyrrolidone, PVP) 300 wt%를 첨가하여 나노유체를 제조하였으며, 산화처리 된 다중벽 탄소나노튜브(Oxidized Multi-Walled Carbon Nanotubes, OMWCNTs)를 증류수에 초음파 분산하여 산화나노유체를 제조하였다. 나노유체의 열전도도는 전기 전도성 유체의 비정상 열선법(Transient Hot-wire Method)을 이용하여 측정하였고, 나노유체의 점도는 회전형 디지털 점도계를 이용하여 측정하였다. 실험 결과, 상온에서 동일 혼합비의 나노유체를 비교했을 때, 산화나노유체가 SDS 100 wt%, PVP 300 wt%를 혼합한 다른 나노유체보다 높은 열전도도 특성을 보였으며 점도 특성 또한 가장 낮은 것으로 측정되었다. 특히 상온에서 0.1vol%의 산화 CM-100 나노유체는 증류수보다 열전도도가 8.34%가 증가하였고, $10^{\circ}C$의 저온에서는 상온에서 증류수와 비교하여 측정된 열전도도 값보다 0.36%가 감소한 7.98%가 증가함을 보였다. 본 연구를 통하여 얻어진 결과는 높은 열전도도를 필요로 하는 열교환기의 작동유체나 기타 활용 분야에 대한 기초 자료로써 유용한 정보를 제공할 것이라 판단된다.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.13 no.6
• /
• pp.509-513
• /
• 2000

The physical and electrical characteristics of MgO and Pt thin-films on it deposited by reactive sputtering and rf magnetron sputtering respectively were analyzed with annealing temperature and time by four point probe SEM and XRD. Under annealing conditions of 100$0^{\circ}C$ and 2 hr, MgO thin-film had the properties of improving Pt adhesion to SiO$_2$and insulation without chemical reaction to Pt thin-film and the sheet resistivity and the resistivity of Pt thin-film deposited on it were 0.1288 Ω/ and 12.88 $\mu$$\Omega$.cm respectively. We made Pt resistance pattern on SiO$_2$/Si substrate by life-off method and fabricated Pt thin-film type microheater for thermal microsensors by Pt-wire Pt-paste and SOG(spin-on-glass). In the temperature range of 25~40$0^{\circ}C$ we estimated TCR(temperature coefficient of resistance) and resistance ratio of thin-film type Pt-RTD(resistance thermometer device). We obtained TCR value of 3927 ppm/$^{\circ}C$ close to the bulk Pt value. Resistance values were varied linearly within the range of the measurement temperature. The thermal characteristics of fabricated thin-films type Pt micorheater were analyzed with Pt-RTD integrated on the same substrate. The heating temperature of Pt microheater could be up to 40$0^{\circ}C$ with 1.5 watts of the heating power.

• Proceedings of the Korean Society of Medical Physics Conference
• /
• 2002.09a
• /
• pp.331-334
• /
• 2002

It has been reported that maximum-likelihood position-estimation (MLPE) algorithms offer advantages of improved spatial resolution and linearity over conventional Anger algorithm in gamma cameras. The purpose of this study is to evaluate the performances of the noise models, Poisson and Gaussian, in MLPE for the localization of photons in a small gamma camera (SGC) using NaI(Tl) plate and PSPMT. The SGC consists of a single NaI(Tl) crystal, 10 cm diameter and 6 mm thick, optically coupled to a PSPMT (Hamamatsu R3292-07). The PSPMT was read out using a resistive charge divider, which multiplexes 28(X) by 28(Y) cross wire anodes into four channels. Poisson and Gaussian based MLPE methods have been implemented using experimentally measured light response functions. The system resolutions estimated by Poisson and Gaussian based MLPE were 4.3 mm and 4.0 mm, respectively. Integral uniformities were 29.7% and 30.6%, linearities were 1.5 mm and 1.0 mm and count rates were 1463 cps and 1388 cps in Poisson and Gaussian based MLPE, respectively. The results indicate that Gaussian based MLPE, which is convenient to implement, has better performances and is more robust to statistical noise than Poisson based MLPE.

• Journal of the Korean Ceramic Society
• /
• v.46 no.4
• /
• pp.419-424
• /
• 2009

Congruent or stoichiometric $LiNbO_3$ fiber single crystals were grown by the $\mu$-PD method, and the grown fiber crystals have the several (2 or 3) ridges with a diameter of $1.35{\sim}1.5\;mm$ and a length of $40{\sim}100\;mm$. In this $\mu$-PD process, different growth rates ($10{\sim}60\;mm/h$) were applied. Pt wire or $LiNbO_3$ crystal was used as a seed. The properties of grown $LiNbO_3$ fiber single crystals having a-axis or c-axis according to seeds were effected by the grown conditions(Pt tube diameter, pulling speed, after heater etc.). Disk-type $LiNbO_3$ samples were poled in condition of DC 5 V/cm at 1050, 1075 or $1100^{\circ}C$. XRD, SEM, conoscope image through the polarized microscope, $T_C$ measuring apparatus, optical transmittance measuring instrument are used to identify the properties of $LiNbO_3$.