• Journal of Climate Change Research
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• v.7 no.4
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• pp.433-442
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• 2016

In this study, we examine future changes in surface radiation associated with cloud amount and aerosol emission over East Asia. Data in this study is HadGEM2-CC (Hadley Centre Global Environmental Model version 2, Carbon Cycle) simulations of the Representative Concentration Pathways (RCPs) 2.6/4.5/8.5. Results show that temperature and precipitation increase with rising of the atmosphere $CO_2$. At the end of $21^{st}$ century (2070~2099) relative to the end of $20^{st}$ century (1981~2005), changes in temperature and precipitation rate are expected to increase by $+1.85^{\circ}C/+6.6%$ for RCP2.6, $+3.09^{\circ}C/+8.5%$ for RCP4.5, $+5.49^{\circ}C/10%$ for RCP8.5. The warming results from increasing Net Down Surface Long Wave Radiation Flux (LW) and Net Down Surface Short Wave Radiation Flux (SW) as well. SW change increases mainly from reduced total Aerosol Optical Depth (AOD) and low-level cloud amount. LW change is associated with increasing of atmospheric $CO_2$ and total cloud amount, since increasing cloud amounts are related to absorb LW radiation and remit the energy toward the surface. The enhancement of precipitation is attributed by increasing of high-level cloud amount. Such climate conditions are favorable for vegetation growth and extension. Expansion of C3 grass and shrub is distinct over East Asia, inducing large latent heat flux increment.

• Infection and chemotherapy
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• v.50 no.4
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• pp.350-356
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• 2018

In acquired immunodeficiency syndrome (AIDS) patients, immune reconstitution inflammatory syndrome (IRIS) due to Mycobacterium avium complex (MAC) infection is one of the most difficult IRIS types to manage. We report an unusual case of MAC-associated IRIS. At first the patient was diagnosed human immunodeficiency virus (HIV) infection after he was admitted with pneumocystis pneumonia. After starting antiretroviral therapy he presented unmasked IRIS with MAC infection. Next, he was hospitalized with continuous loose stools and new-onset fever. Investigation included computed tomography (CT), which showed homogeneous enhancement and enlargement of the lymph nodes (LN), elevation of ferritin (>1,650 ng/mL) and lactate dehydrogenase (306 IU/L) levels, and F- fluorodeoxyglucose positron emission tomography/computed tomography (FDG PET/CT) scan, which showed increased FDG uptake. These findings were highly indicative of lymphoma. We performed laparoscopic biopsy of the mesenteric LN, and the biopsy culture grew MAC. So we made a diagnosis of MAC-associated. Therefore, IRIS must be considered as a possible diagnosis when AIDS patients develop new symptoms or exhibit exacerbations of existing symptoms. Furthermore the biopsies should be conducted.

• Asia-Pacific Journal of Business
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• v.11 no.3
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• pp.169-184
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• 2020

Purpose - This research is intended to analyze the current status and problems of tax benefits in the R&D sector and suggest ways to improve tax credit for research and manpower development expenses when various countries fiercely develop efforts to enhance national competitiveness through increased investment in R&D Design/methodology/approach - This study will examine the current status of the tax support system for domestic and foreign R&D, and suggest improvement measures to expand research and development activities in the future. Findings - First, a plan may be considered to abolish and perpetuate the sunset deadline for tax credit for research and manpower development expenses as in the case of the United States and Japan. This perpetuation can be a proactive measure to actively support long-term R & D investment in companies facing economic decisions under uncertainty. Second, it should be revised to raise the tax credit rate of large corporations, which are shrinking every year, compared to SMEs, so that both large corporations and SMEs can improve their international competitiveness and secure excellent technologies through R & D. Finally, the target technologies for each new growth engine and source technology should be expanded to various fields, including national cybersecurity enhancement technology, aviation engine technology, carbon emission and global cooling technologies, which are areas of interest in major overseas R&D countries, to help active R&D and investment in these areas. Research implications or Originality - This study can find a contribution in comparing and analyzing the national R&D tax support system and presenting improvement measures at a time when the benefits of tax credit for research and manpower development expenses of large companies are decreasing due to frequent tax law revisions and the government's factors of increasing tax revenues. In addition, recent research and development items and research technologies of foreign countries were analyzed by Nature's top 10 major science and technology issues, and advanced technologies that should be applied to target technology areas by new growth engine and source technology were specifically investigated and presented.

• Applied Chemistry for Engineering
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• v.32 no.3
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• pp.237-242
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• 2021

Simultaneous removal technologies of multi-pollutants such as particulate matters (PMs), NOx, SOx, VOCs and ammonia have received consistent attention due to the enhancement of pollutant abatement efficiency in addition to the stringent environmental regulation and emission standard. Pretreatment of insoluble NO by an ozone oxidation can be considered to be more effective route for saving space occupation as well as operation cost in comparison with that of traditional selective catalytic reduction (SCR) process. Moreover the primary advantage of ozone oxidation process is that the simultaneous removal with acidic gas including SOx is also available. Herein, we highlight recent studies of multi-pollutant abatement via ozone oxidation process and the promising research topics for better application in industrial sectors.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 1999.10a
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• pp.59-59
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• 1999

In this study, planer inductively coupled $Cl_2$ based plasmas were used to etch InGaN and the effects of plasma conditions on the InGaN etch properties have been characterized using quadrupole mass spectrometry(QMS) and optical emission spectroscopy(OES). As process conditions used to study the effects of plasma characteristics on the InGaN etch properties, $Cl_2$ was used as the main etch gas and $CHF_3,{\;}CH_4$, and Ar were used as additive gases. Operational pressure was varied from SmTorr to 3OmTorr, inductive power and bias voltage were varied from 400W to 800W and -50V to -250V, respectively while the substrate temperature was fixed at 50 centigrade. For the $Cl_2$ plasmas, selective etching of GaN to InGaN was obtained regardless of plasma conditions. The small addition of $CHF_3$ or Ar to $Cl_2$ and the decrease of pressure generally increased InGaN etch rates. The selective etching of InGaN to GaN could be obtained by the reduction of pressure to l5mTorr in $CI_2/IO%CHF_3{\;}or{\;}CI_2/IO%Ar$ plasma. The enhancement of InGaN etch rates was related to the ion bombardment for $CI_2/Ar$ plasmas and the formation of $CH_x$ radicals for $CI_2/CHF_3(CH_4)$ plasmas.

• Journal of Advanced Navigation Technology
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• v.28 no.4
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• pp.574-581
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• 2024

This study explores the usability of extended reality (XR) content tailored for production process training, with a focus on user experience. Participants engaged with extended reality training modules, and qualitative data was subsequently collected through interviews. These interviews evaluated the hardware, user interface, and overall user satisfaction. The analysis utilized python packages for keyword extraction and word cloud visualization, offering insights into user perceptions. The findings revealed that although the hardware was deemed comfortable, concerns were raised regarding its weight and heat emission. The interactive interface, which relies on hand tracking, encountered issues with recognition rates, leading to suggestions for alternative input methods. Users acknowledged extended reality's potential impact on industries like healthcare and education, sharing both positive and negative views on the technology. This research enhances our understanding of user responses and guides the future enhancement of extended reality content for industrial applications, aiming to improve its quality and practical usability

• Proceedings of the Materials Research Society of Korea Conference
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• 2003.11a
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• pp.27-27
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• 2003

최근 탄소나노튜브를 전계방출 표시소자(FED, field omission display)용 에미터 재료로 사용한 캐소드 개발에 대한 연구가 활발히 진행되고 있다. 캐소드전극으로는 투명전도성 반도체 박막인 ITO를 사용하고, 에미터용 재료로는 탄소나노튜브를 사용해서 스크린 인쇄법으로 2극(diode type)형 전계방출 소자용 캐소드를 제작하였다. 본딩재(bonding materials)의 종류와 공정변수를 달리해서 에미터용 탄소나노튜브와 ITO 캐소드 전극 사이의 전기적 접촉방법을 변화시켰을때 탄소나노튜브 캐소드의 전계방출 특성을 체계적으로 연구하였다. 첫째로, 본딩재의 전기전도성 (electrical conductivity)을 변수로 해서 탄소나노튜브 에미터의 전계강화(fold enhancement) 효과를 연구한 결과 본딩재의 구성 성분중 부도체(insulator)의 분율이 높을수록 전계강화 효과가 크게 나타남을 확인하였다. 두 번째로, ITO박막 캐소드전극과 탄소나노튜브 잉크 사이에 중간층(inter layer)을 형성시켜서 중간층이 전계방출 특성에 미치는 영향을 연구하여, 중간층의 존재가 탄소나노튜브의 전계방출 전류의 균일성과 전류밀도의 증가에 기여하는 것을 확인하였다. 본 연구의 결과 전계방출 전류가 안정적이면서 동시에 전계방출 효율이 크게 개선된 탄소나노튜브 캐소드를 제작하는 공정기술이 개발되었다. 개발된 기술은 기존의 방법에 비해서 탄소나노튜브 캐소드의 진공패키징시 아웃개싱(outgassing)의 양도 현격하게 작았으며, 에미터와 캐소드 전극 사이의 본딩력(adhesion)도 우수해서 항후 탄소나노튜브 전계방출 표시소자의 개발에 크게 기여할 것으로 판단된다.luminum 첨가량이 증가함에 따라 세라믹 수율도 증가하였음을 확인하였다. 합성된 aluminum-contained polycarbosilane은 20$0^{\circ}C$에서 1시간 동안 불융화과정을 거쳐 환원 및 진공 분위기에서 고온 열처리하였으며 이로부터 얻어진 시료에 대해 XRD분석을 수행하였다. SEM과 TEM을 이용하여 미세구조를 관찰하였다./100 duty로 구동하였으며, duty비 증가에 따라 pulse의 on-time을 고정하고 frequency를 변화시켰다. dc까지 duty비가 증가됨에 따라 방출전류의 양이 선형적으로 증가하였다. 전압을 일정하게 고정시키고 각 duty비에서 시간에 따라 방출전류를 측정한 결과 duty비가 높을수록 방출전류가 시간에 따라 급격히 감소하였다. 각 duty비에서 방출전류의 양이 1/2로 감소하는 시점을 에미터의 수명으로 볼 때 duty비 대 에미터 수명관계를 구해 높은 duty비에서 전계방출을 시킴으로써 실제의 구동조건인 낮은 duty비에서의 수명을 단시간에 예측할 수 있었다. 단속적으로 일어난 것으로 생각된다.리 폐 관류는 정맥주입 방법에 비해 고농도의 cisplatin 투여로 인한 다른 장기에서의 농도 증가 없이 폐 조직에 약 50배 정도의 고농도 cisplatin을 투여할 수 있었으며, 또한 분리 폐 관류 시 cisplatin에 의한 직접적 폐 독성은 발견되지 않았다이 낮았으나 통계학적 의의는 없었다[10.0%(4/40) : 8.2%(20/244), p>0.05]. 결론: 비디오흉강경술에서 재발을 낮추기 위해 수술시 폐야 전체를 관찰하여 존재하는 폐기포를 놓치지 않는 것이 중요하며, 폐기포를 확인하지 못한

• Proceedings of the Korean Society of Medical Physics Conference
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• 2004.11a
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• pp.100-103
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• 2004

Experiments and simulation were done to study the impact of contrast agent when CT scan was used to attenuation correction for PET images in PET/CT system. Whole body phantom was imaged with various concentration of iodine-based contrast agent using CT. Mathematical emission and transmission density map with liver were made to simulate for whole body FDG imaging. Various transmission density maps was generated with non-uniform enhancement of contrast agent, hypo-attenuating of contrast agent for tumor, different concentration of contrast agent, and so on. Attenuation correction was done with all transmission maps. In the experiments, we confirmed that attenuation coefficient was changed by concentration of contrast agent. From the simulation data, image quality of attenuation corrected images was affected by contrast agent and artifact was produced by contrast agent. These results indicated that the contrast agent should be used with a full understanding of its potential problem in PET/CT system.

• Journal of the Korean Vacuum Society
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• v.18 no.6
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• pp.474-480
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• 2009

We have investigated optical properties of InAs quantum dots (QDs) grown on GaAs (100) substrate by molecular beam epitaxy, by means of photoluminescence (PL) and time-resolved PL spectroscopy. InAs QDs were grown by using In interruption growth technique, in which the In flux was periodically interrupted by a closed In shutter during InAs QDs growth. The shutter of In source was opened for 1 s and then closed for 0, 9, 19, 29, or 39 s. This growth sequence was repeated 30 times during QDs growth. For each sample, the total amount of In contributing to the growth was the same (30 s) but total growth time was varied during the InAs growth. As the In interruption time is increased from 0 to 19 s, the PL peak position of the QDs is red-shifted from 1096 to 1198 nm, and the PL intensity is increased. However, the PL peak is unchanged and the intensity is decreased as the In interruption time is increased further to 39 s. The PL decay times measured at the PL peak position for all the InAs QDs are independent on the QD growth conditions and showed about 1 ns. The red-shift of PL peak and the increase of PL intensity can be explained due to increased QD size and the enhancement in the migration of In atoms using In interruption technique. These results indicated that the size and shape of InAs QDs can be controlled by using In interruption growth technique. Thus the emission wavelength of the InAs QDs on GaAs substrate can also be controlled.

• Journal of the Korean Chemical Society
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• v.43 no.6
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• pp.636-643
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• 1999

Green-emission intensity of a $Zn_{2-x}Mn_xSiO_4$ phosphor, which is a potential candidate as a green component in PDP device, significantly increases provided that the compound is additionally heat treated at 900$^{\circ}C$ after solid state reaction at 1300$^{\circ}C$. In order to verify origin of such an intensity enhancement after the additional heat treatment in association with the electronic and local structural change at around Mn ions, the Mn K-edge X-ray absorption spectra were recorded. From the analyses of the preedge peak corresponding to $1s{\rightarrow}3d$ bound state transition and XANES spectrum, it is known that most Mn ions are in +2 oxidation state and substitute Zn ion site regardless of the thermal treatment. In addition, EXAFS analyses revealed that Mn ions formed $MnO_4$ tetrahedra with the Mn-O bond length shortened by 0.01${\AA}$ and with reduced Debye-Waller factor in the thermally treated sample.