• 한국레이저가공학회지
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• 제11권1호
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• pp.19-24
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• 2008

It has been recognized that laser dicing of wafers results in low mechanical strength compared to the conventional sawing techniques. Thermal shock generated by rapid thermal loading is responsible for this problem. This work presents a two-dimensional ultra-short thermo elastic model for numerical simulation of femtosecond laser ablation of metals in the high-fluence regime where the phase explosion is dominant. Laser-induced thermoelastic stress is analyzed for Ni. The results show that the laser-induced thermal shock is large enough to induce mechanical damages.

• 한국정밀공학회지
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• 제26권6호
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• pp.36-40
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• 2009

Development of maskless lithography techniques can provide a potential solution for the photomask cost issue. Furthermore, it could open a market for small scale manufacturing applications. Since femtosecond lasers have been found suitable for processing of a wide range of materials with sub-micrometer resolution, it is attractive to use this technique for maskless lithography. As a femtosecond laser has recently been developed, both of high power and high photon density are easily obtained. The high photon density results in photopolymerization of photoresist whose absorption spectrum is shorter than that of the femtosecond laser. The maskless lithography using the two-photon absorption (TPA) makes micro structures. In this paper, we present a femtosecond laser direct write lithography for submicron PR patterning, which show great potential for future application.

• Carbon letters
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• 제14권3호
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• pp.131-144
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• 2013

The carbon nanotube (CNT) represents one of the most unique inventions in the field of nanotechnology. CNTs have been studied closely over the last two decades by many researchers around the world due to their great potential in different fields. CNTs are rolled graphene with $SP^2$ hybridization. The important aspects of CNTs are their light weight, small size with a high aspect ratio, good tensile strength, and good conducting characteristics, which make them useful as fillers in different materials such as polymers, metallic surfaces and ceramics. CNTs also have potential applications in the field of nanotechnology, nanomedicine, transistors, actuators, sensors, membranes, and capacitors. There are various techniques which can be used for the synthesis of CNTs. These include the arc-discharge method, chemical vaporize deposition (CVD), the laser ablation method, and the sol gel method. CNTs can be single-walled, double-walled and multi-walled. CNTs have unique mechanical, electrical and optical properties, all of which have been extensively studied. The present review is focused on the synthesis, functionalization, properties and applications of CNTs. The toxic effect of CNTs is also presented in a summarized form.

• 대한핵의학회:학술대회논문집
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• 대한핵의학회 2002년도 제23차 연수교육
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• pp.77-95
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• 2002

During the last several decades, prognosis of differentiated thvroid cancers improved markedly, mainly due to refinement of surgical techniques and routine use of radioactive iodine. Total or neat-total thyroidectomy is to be performed as the first line of treatment. Routine remnant ablation just after surgery decreases recurrence and increases survival. After then patients are maintained on suppressive dose of thyroid hormone to keep endogenous TSH below normal. Regular follow-up of the patients with serum thyroglobulin measurement and iodine whole body scan after thyroid hormone withdrawal or under recombinant human thyrotropin stimulation select high risk patients with recurrence or metastatic disease and treatment with therapeutic dose of radioactive iodine prolongs survival and sometimes leads cure. Currently recommended diagnostic and therapeutic strategies, present controversies and future directions are discussed.

• 한국표면공학회지
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• 제24권2호
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• pp.67-72
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• 1991

The feasibility of preparing superconducting $Y_1Ba_2Cu_3O_y$ films on metallic substrate was exmined in an attempt to fabricate a tape conductor. Deposition methods employed were sputtering, laser ablation, and plasma flash evaporation. Although zero resistance temperature (Tc) is achieved above 90 K, critical current density values (Jc) obtained so far is still low as compared with those reported in the films grown on single crystal substrates. This may be caused by the misalignment of the crystal structure of the films on metal substrates. A further improvement if Jc for highly-oriented polycrystalling films is being investigated at the present time.

• 한국멀티미디어학회논문지
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• 제22권10호
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• pp.1149-1159
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• 2019

We present a novel deep learning architecture for obtaining a latent image from a single blurry image, which contains dynamic motion blurs through object/camera movements. The proposed architecture consists of two sub-modules: blur image restoration and optical flow estimation. The tasks are highly related in that object/camera movements make cause blurry artifacts, whereas they are estimated through optical flow. The ablation study demonstrates that training multi-task architecture simultaneously improves both tasks compared to handling them separately. Objective and subjective evaluations show that our method outperforms the state-of-the-arts deep learning based techniques.

• International Journal of Computer Science & Network Security
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• 제21권9호
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• pp.281-291
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• 2021

The Islamic jurisprudential legal system represents an essential component of the Islamic religion, that governs many aspects of Muslims' daily lives. This creates many questions that require interpretations by qualified specialists, or Muftis according to the main sources of legislation in Islam. The Islamic jurisprudence is usually classified into branches, according to which the questions can be categorized and classified. Such categorization has many applications in automated question-answering systems, and in manual systems in routing the questions to a specialized Mufti to answer specific topics. In this work we tackle the problem of automatic categorisation of Islamic jurisprudential legal questions using deep learning techniques. In this paper, we build a hierarchical deep learning model that first extracts the question text features at two levels: word and sentence representation, followed by a text classifier that acts upon the question representation. To evaluate our model, we build and release the largest publicly available dataset of Islamic questions and answers, along with their topics, for 52 topic categories. We evaluate different state-of-the art deep learning models, both for word and sentence embeddings, comparing recurrent and transformer-based techniques, and performing extensive ablation studies to show the effect of each model choice. Our hierarchical model is based on pre-trained models, taking advantage of the recent advancement of transfer learning techniques, focused on Arabic language.

• Journal of Chest Surgery
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• 제41권4호
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• pp.469-475
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• 2008

배경: 비디오흉강경에 의한 흉부 교감신경차단술은 겨드랑이다한증을 치료하는데 최소침습 치료방법의 하나이다. 여러 다른 수기들이 겨드랑이다한증을 치료하는데 이용되고 있으나 효과가 일시적이고 고비용인 단점이 있다. 본 연구는 겨드랑이다한증 치료에 있어서 2개 부위의 흉부교감신경차단수술(T3-4대 T4)후 조기와 만기 결과를 비교하였다. 대상 및 방법: 2002년 6월부터 2007년 5월까지 원광대학교병원 흉부외과에서 겨드랑이다한증환자 30명에서 2개 부위(T3-4대 T4)의 흉부 교감신경차단 수술 후 후향적으로 조사를 하였다. 모든 환자에서 수술은 단일기도관을 이용한 전신마취하에서 양측으로 동시에 2개의 2 mm 투관침과 2 mm 흉강경을 이용하여 시행하였다. T3-4군은 2002년 6월부터 2004년 6월까지 15명으로 T3-4 교감신경차단수술을 늑골 3, 4번 늑골 상에서 시행하였고, T4군은 15명으로 4번 늑골 상에서 4번 흉부 교감신경차단수술을 시행하였다. 양군의 치료의 만족도, 보상성 다한증의 빈도와 정도, 그리고 술 후의 합병증을 조사하였고, 또한 T.I.P.I에 의한 술 전 후의 체열변화를 조사하였다. 만기의 결과는 환자와의 전화면담으로 시행하였다. 결과: 평균 추적기간은 T3-4군은 $38.7{\pm}6.5$개월, T3군은 $18.7{\pm}3.6$개월이었다. 수술 직후의 만족도는 양군에서 100%이었으나 만기의 만족도는 보상성다한증의 정도에 의해서 T3-4군은 53.3%,74군은 93.3%를 보였다. 보상성다한증은 불편한 정도 이상이 T3-4군은 46.7%를 보였으나 T4군은 6.7%를 보여 만기의 만족도는 보상성다한증의 정도와 일치하였다. 또한 T.I.P.I에 의한 체열검사에서는 양군 모두 의의 있는 체열상승을 보여주었다. 술 후의 합병증으로는 경도의 공기가슴증과 늑간신경통을 보였으나 모두 다 문제없이 해결되었다. 결론: 양 수술의 수기는 겨드랑이다한증을 치료하는 데 효과적이었다. T4교감신경차단수술이 보다 높은 만족도를 보였고 보상성다한증의 정도와 빈도는 낮았다.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2016년도 제50회 동계 정기학술대회 초록집
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• pp.421.1-421.1
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• 2016

We studied indium-doped zinc oxide (IZO) film grown by atomic layer deposition (ALD) as transparent conductive oxide (TCO). A variety of TCO layer, such as ZnO:Al (AZO), InSnO2(ITO), Zn (O,S) etc, has been grown by various method, such as ALD, chemical vapor deposition (CVD), sputtering, laser ablation, sol-gel technique, etc. Among many deposition methods, ALD has various advantages such as uniformity of film thickness, film composition, conformality, and low temperature deposition, as compared with other techniques. In this study, we deposited indium-doped zinc oxide thin films using diethyl[bis(trimethylsilyl)amido]indium [Et2InN(TMS)2] as indium precursor, DEZn as zinc precursor and H2O as oxidant for ALD and investigated the optical and electrical properties of IZO films. As an alternative, this liquid In precursor would has several advantages in indium oxide thin-film processes by ALD, especially for low resistance indium oxide thin film and high deposition rate as compared to InCp, InCl3, TMIn precursors etc. We found out that Indium oxide films grown by Et2InN(TMS)2 and H2O precursor show ALD growth mode and ALD growth window. We also found out the different growth rate of Indium oxide as the substrate and investigated the effect of the substrate on Indium oxide growth.

• 한국분말재료학회지
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• 제15권1호
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• pp.46-52
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• 2008

The restrictor, which is a fluid channel from a reservoir to a chamber inside a thermal micro actuator, has been fabricated using ArF and KrF excimer lasers, Diode-Pumped Solid State Lasers (DPSSL) and femtosecond lasers for a feasibility study. A numerical model of fluid dynamics for the actuator chamber and restrictor is presented. The model includes bubble formation and growth, droplet ejection through nozzle, and dynamics of fluid refill through the restrictor from a reservoir. Since an optimized and well-fabricated restrictor is important for a high frequency actuator, some special beam delivery setups and post processing techniques have been researched and developed. The effects of variations of the restrictor length, diameter, and tapered shapes are simulated and the results are analyzed to determine the optimal design. The numerical results of droplet velocity and volume are compared with the experimental results of a cylindrical-shaped actuator. It is found that the micro actuators having tapered restrictors show better high frequency characteristics than those having a cylindrical shape without any notable decrease of droplet volume. The laser-fabricated restrictors demonstrate initial feasibility for the laser direct ablation technique although more development is required.