• Korean Journal of Cognitive Science
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• v.33 no.1
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• pp.51-75
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• 2022

Transcranial direct current stimulation (tDCS) is a non-invasive brain stimulation that is able to alter neuronal activity in particular brain regions. Many studies have researched how tDCS modulates neuronal activity and reorganizes neural networks. However it is difficult to conclude the effect of brain stimulation because the studies are heterogeneous with respect to the stimulation parameter as well as individual difference. It is not fully in agreement with the effects of brain stimulation. In particular few studies have researched the reason of variability of brain stimulation in response to time so far. The study investigated individual variability of brain stimulation based on circadian rhythm and chronotype. Participants were divided into two groups which are morning type and evening type. The experiment was conducted by Zoom meeting which is video meeting programs. Participants were sent experiment tool which are Muse(EEG device), tdcs device, cell phone and cell phone holder after manuals for experimental equipment were explained. Participants were required to make a phone in frount of a camera so that experimenter can monitor online EEG data. Two participants who was difficult to use experimental devices experimented in a laboratory setting where experimenter set up devices. For all participants the accuracy of 98% was achieved by SVM using leave one out cross validation in classification in the the effects of morning stimulation and the evening stimulation. For morning type, the accuracy of 92% and 96% was achieved in classification in the morning stimulation and the evening stimulation. For evening type, it was 94% accuracy in classification for the effect of brain stimulation in the morning and the evening. Feature importance was different both in classification in the morning stimulation and the evening stimulation for morning type and evening type. Results indicated that the effect of brain stimulation can be explained with brain state and trait. Our study results noted that the tDCS protocol for target state is manipulated by individual differences as well as target state.

• Proceedings of the Korean Information Science Society Conference
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• 1998.10a
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• pp.671-673
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• 1998

전력 및 전화 서비스와 같은 저속의 댁내 망 구축에서 서비스 품질을 보장하는 다양한 대역폭의 멀티미디어 및 멀티포인트 서비스를 효율적으로 제공할 수 있는 댁내 망 구축 및 동영상 압축 기술 및 디지털 신호처리 기술의 발전으로 인해 댁내의 디지털 가전 기기들이 고속의 통신 기능이 탑재되는 정보 가전으로 발전하고 있다. 본 논문에서는 현재 활발히 다양한 댁배 망 서비스를 제공하고 잇는 RBB서비스 제공자들의 현황을 알아보고, 액세스 망을 통한 서비스와 댁내에서의 통신 서비스를 제공하기 위해서 댁내 망이 갖추어야할 조건을 분석한다. 또한, 앞으로 댁내 망 일반 사용자들이 이용하게 될 댁내외 서비스를 만족시키기 위한 서비스 요구사항에 대하여 기술한다.

• Proceedings of the Korea Institute of Fire Science and Engineering Conference
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• 2010.04a
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• pp.31-36
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• 2010

원전 방화지역에서 화재가 발생할 경우 케이블 고장으로 인한 기기의 오동작 및 안전정지 기능에 미치는 영향 평가가 필요하다. 본 논문에서 FDS의 THIEF 모델을 이용하여 환기조건 및 열발생율 변화에 따른 원전 안전정지 케이블의 열적 특성을 분석하였다.

• Journal of the Society of Disaster Information
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• v.10 no.4
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• pp.583-597
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• 2014

Fire caused by heater has various causes as many as the types of heater. also, lots of damage of human life and property loss are caused, since annually continuous fire accident by heater in traditional market is frequently occurring. There are not many cases of fire due to heater in most of residential facilities such as general house, apartments, etc., because they are supplied with heating boiler, however the restaurant, store and office of the market, sports center, factory, workplace, etc. still use heater, e.g. oilstove, electric heater, etc., so that they are exposed to fire hazard. Also, when investigating the number of fire due to heater, it was analyzed to occur in order of home boiler, charcoal stove, oilstove, gas heater/stove, electric stove/heater, the number of fire per human life damage was analyzed in order of gas heater/stove, oil heater/stove, electric heater/stove, briquette/coal heater. Also, gas and oil related heater were analyzed to have low frequency, however, with high fire intensity. Therefore, this research aimed at considering more scientific fire inspection and identification approach by reenacting and reviewing fire outbreak possibility caused by combustibles' contact and conductivity under the normal condition and abnormal condition in respect of ignition hazard, i.e. minimum ignition temperature, carbonization degree and heat flux along with it, due to oilstove and electric stove, which are still frequently used in public use facility, traditional market, and, of which actual fire occurrence is the most frequent. As the result of reenact test, ignition hazard appeared very small, as long as enough heat storage condition is not made in both test objects(oilstove/electric stove), however carbonization condition was analyzed to be proceeded per each part respectively. Eventually, transition to fire is the ignition due to heat storage, so that it was analyzed to ignite when minimum heat storage temperature condition of fire place is over $500^{\circ}C$. Particularly, in case of quartz pipe, the heating element of electric stove, it is rapidly heated over the temperature of $600^{\circ}C$ within the shortest time(10sec), so that the heat flux of this appears 6.26kW/m2, which was analyzed to result in damage of thermal PVC cable and second-degree burn in human body. Also, the researcher recognized that the temperature change along with Geometric View Factor and Fire Load, which display decrease of heat, are also important variables to be considered, along with distance change besides temperature condition. Therefore, the researcher considers that a manual of careful fire inspection and identification on this is necessary, also, expects that scientific and rational efforts of this research can contribute to establish manual composition and theoretical basis on henceforth fire inspection and identification.

• Korean Chemical Engineering Research
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• v.59 no.1
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• pp.100-105
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• 2021

This paper proposes the polydimethylsiloxane (PDMS) blade coating method for fabrication of paper-based analytical device (PAD) that is able to monitor the disease diagnosis and progress without special analytical equipment. The mold that has PAD design is easily modified by using laser cutting technique. And the fabricated mold is used for hydrophobic barrier formation by blade coating. We have optimized the stable formation of PDMS hydrophobic barrier as blade coating condition, which is established by analyzing the structure of the PDMS hydrophobic barrier and change of hydrophilic channel size as thickness of the ink and contact time with the chromatography paper. Based on optimal condition, we demonstrate that PAD as biosensor can apply to detect protein, glucose, and metal ion without special analysis equipment.

• Proceedings of the Materials Research Society of Korea Conference
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• 2009.11a
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• pp.46.2-46.2
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• 2009

휴대전화, 랩톱 컴퓨터 등 각종 모바일기기 및 디스플레이 기기의 경박단소화 및 고기능화에 따라 연성회로기판(FPCB)의 사용량이 증가하고있다. 연성회로기판의 핵심소재인 동박적층필름(FCCL)은 폴리이미드필름과 접착층, Cu 층으로 구성되는데, 이 중접착층으로 사용되는 Ni-20Cr합금은 에칭공정 후 Cr의 잔류에 의해 불량률 증가가 문제되고 있어, Ni-Cr합금 스퍼터링 타깃의 Cr 함량 저감 또는 Cr-free Ni합금 개발 등이 요구되고 있다. 본 연구에서는 차세대 FCCL 본드층에 적합한 Ni기 합금을 개발하기 위한 기초연구로써 Cr 함량 및 가공열처리조건에 따른 미세조직과 집합조직 변화를 조사하였다. 4N급의 고순도Ni과 Cr을 진공 플라즈마 용해장치로 용해하여Ni-xCr (x=5, 10, 15, 20wt.%)합금 잉곳을 만들고, 이를 두께감소율 90%로 냉간압연한 후, $600^{\circ}C$ 및 $800^{\circ}C$에서 10~120분 동안 어닐링하여 시편을 준비하였다. 광학현미경으로 미세조직을 관찰하고, Micro-Vickers 경도시험을 통해 어닐링 조건에 따른 경도변화를 조사하였다. 또한 SEM-EBSD를 이용하여 집합조직 및 입계특성을 분석하였다. $600^{\circ}C$ 어닐링 시 Cr함량이 증가할수록 재결정 완료시간이 증가하여 Ni-20Cr합금의 경우 2시간이상 어닐링에도 재결정이 일어나지 않았다. $800^{\circ}C$ 어닐링 시 10분 어닐링 조건에서 4종류 합금 모두 재결정이 완료되었으며, 동일한 어닐링 조건에서 Cr함량이 증가할수록 결정립이 작아지는 것으로 나타났다. $800^{\circ}C$ 2시간 어닐링 조건에서 Ni-5Cr 합금의 주요 집합조직은 {223}<113>과 {122}<112>로 나타났으며, 이중 {223}<113>은Cr 함량이 증가함에 따라 점차 {122}<112>에 가까운 방향으로 변화되어 Ni-20Cr 합금의 경우 {123}<112>만이 형성되었다. 이러한 집합조직의 변화는 적층결함에너지 감소에 의한 ${\Sigma}3$ 입계의 분율 증가와 밀접한 관련이 있는 것으로 사료된다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.38C no.4
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• pp.402-407
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• 2013

In this paper, we consider an interference scenario and interference simulation method of intra-wireless vessel communications using SEAMCAT (Spectrum Engineering Advanced Monte-Carlo Analysis) simulator. The interference between electromagnetic equipment and low power radio apparatus can deteriorate a stability of vessel system and it is necessary to analyze the interference probability between radio devices. The proposed simulation method in the 13.56MHz ISM frequency band shows that the interference effect can be minimized when the distance between the devices is greater than 4.7m and 2.7m in case that the victim receiver (VR) are RFID and remote control(RC) toy, respectively. The proposed interference scenario and simulation method are expected to be helpful in the interference probability analysis and regulation policy in the ISM frequency band.

• Journal of KIISE
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• v.42 no.8
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• pp.1022-1030
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• 2015

The context-awareness of mobile applications yields several issues for testing, since mobile applications should be able to be tested in any environment and under any contextual input. In previous studies of testing for Android applications as an event-driven system, many researchers have focused on using generated test cases considering only Graphical User Interface (GUI) events. However, it is difficult to find failures that could be detected when considering the changes in the context in which applications run. It is even more important to consider various contexts since the mobile applications adapt and use the new features and sensors of mobile devices. In this paper, we provide a method of systematically generating various executing contexts from permissions. By referring to the lists of permissions, the resources used by the applications for running Android applications can be easily inferred. To evaluate the efficiency of our testing method, we applied the method on two open source projects and showed that it contributes to improve the statement code coverage.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.28 no.5
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• pp.382-390
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• 2017

In this paper, we consider particular exposure scenarios to evaluate human effects for inductive commercial wireless charging device operating at low frequency. The coil used in this study is the A10 model in Qi standard proposed by WPC(Wireless Power Consortium), and input power is 5 W to the operating frequency of 155 kHz. In perfectly aligned condition, the max leakage magnetic field is $257.58{\mu}T$ which is obtained at the side of the device, and it is exceeded about 7.4 times of the ICNIRP 1998 reference level. The SAR is evaluated with homogeneous phantom which has electric constants of wet skin. The max value of the SAR is $134.47{\mu}W/kg$ which is obtained at the side of the device also, and it is much lower than the international guidelines. Especially, it showed higher SAR values in case of misalignment condition, so we will need to consider the misalignment condition importantly when we evaluate human effects for wireless power transfer system.

• Proceedings of the Korean Fiber Society Conference
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• 1997.04a
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• pp.26-31
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• 1997

유리섬유/nylon 6 복합재료의 계면결합강도를 증가시키기 위하여 r-APS(r-Aminopropyltriethoxysilane)로 유리섬유의 표면을 처리 하였다. 이때 표면처리의 최적 조건을 찾기위해서 처리후 기기분석과 계면결합강도 측정 등을 하였다. 농도, pH, 처리시간, 온도를 변화시키면서 표면처리를 한 후 흡착량을 살펴본 결과 처리 농도에 의해서는 흡착량이 단조증가하였으며 처리시간에 따라서는 5분정도에서, 처리온도에 의해서는 30C 부근에서 최대 흡착량을 보였다. 또한 pH에 따른 흡착량은 silane의 고유 pH인 10.5부근에서 최대치를 나타냈다. FR-IR 분석에 의하면 NH2의 NH3 bending mode가 1607cm-1, 1575cm-1에서 나타났으며 SiOH의 SiO band는 960cm-1에서 나타났다. XPS를 통해서는 N ls와 Si 2p의 존재를 확인할 수 있었다. 표면처리된 유리섬유와 matrix인 nylon 6를 이용해 단섬유내장시편을 만들어 fragmentation test를 한 결과 계면결합강도는 약 5분의 처리시간과 1%(wt%)의 농도에서 최대값을 보였다.