인공지능과 증강현실 기술을 이용한 모래성 놀이 가이드 애플리케이션 설계 및 구현

류지승,장승우,문유정,이정진 (사)한국컴퓨터그래픽스학회 2022 컴퓨터그래픽스학회논문지 Vol.28 No.3

With the popularity and the advanced graphics hardware technology of mobile devices, various mobile applications that help children with physical activities have been studied. This paper presents SandUp, a mobile application that guides the play of building sand castles using artificial intelligence and augmented reality(AR) technology. In the process of building the sandcastle, children can interactively explore the target virtual sandcastle through the smartphone display using AR technology. In addition, to help children complete the sandcastle, SandUp informs the sand shape and task required step by step and provides visual and auditory feedback while recognizing progress in real-time using the phone’s camera and deep learning classification. We prototyped our SandUp app using Flutter and TensorFlow Lite. To evaluate the usability and effectiveness of the proposed SandUp, we conducted a questionnaire survey on 50 adults and a user study on 20 children aged 4∼7 years. The survey results showed that SandUp effectively helps build the sandcastle with proper interactive guidance. Based on the results from the user study on children and feedback from their parents, we also derived usability issues that can be further improved and suggested future research directions. 최근 스마트폰이 널리 보급되고 모바일 기기의 그래픽스 처리 성능이 발전함에 따라 아이들의 물리적인 활동을 돕는다양한모바일 애플리케이션들이 연구되고 있다. 본 논문에서는 인공지능과 증강현실 기술을 활용해 모래성 쌓기 놀이를 안내하는모바일 애플리케이션 SandUp을 제안한다. 모래성을 쌓는 과정에서 아이는 모바일 증강현실 기술을 활용해 제시된 목표 모래성을 현실 세계에 증강하여 살펴볼 수 있다. 또한, SandUp은 모래성의 완성을 돕기 위해 단계적으로 필요한 모래 모양과Task를 알려주고, 모바일 폰의 카메라와 딥러닝 인식모델을이용해 실시간으로 현재 진행 상황을인식하고 시각적, 청각적피드백을 제공한다. 우리는 Flutter와 TensorFlow Lite를 이용해 SandUp 앱의 프로토타입을 구현하였다. 제안하는 SandUp 앱의사용성과효과를평가하기위해성인을대상으로설문조사를수행하고앱이목표로한4-7세아이들을모집하여실험을진행했다. 실험 결과와 학부모의 피드백을 분석하여앱의 발전 가능성 및 개선점을 도출하고 향후 연구 방향을 제시한다.

Sr 함량이 Cu-doped LSM(La_1-xSr_xMn_0.8Cu_0.2O₃)의 구조적변화와 전기전도도에 미치는 영향

류지승,노태민,김진성,이희수,Ryu, Ji-Seung,Noh, Tai-Min,Kim, Jin-Seong,Lee, Hee-Soo 한국결정성장학회 2012 한국결정성장학회지 Vol.22 No.2

The structural change and the electrical conductivity with Sr content in $La_{1-x}Sr_xMn_{0.8}Cu_{0.2}O_3$ (LSMCu) were studied. $La_{0.8}Sr_{0.2}MnO_3$ (LSM) and $La_{1-x}Sr_xMn_{0.8}Cu_{0.2}O_3$ ($0.1{\leq}x{\leq}0.4$) were synthesized by EDTA citric complexing process (ECCP). A decrease in the lattice parameters and lattice volumes was observed with increase of Sr content, and these results were attributed to the increasing $Mn^{4+}$ ions and $Cu^{3+}$ ions in B-site. The electrical conductivity measured from $500^{\circ}C$ to $1000^{\circ}C$ was increased with increase of Sr content in the $0.1{\leq}x{\leq}0.3$ composition range, and it was 172.6 S/cm (at $750^{\circ}C$) and 177.7 S/cm (at $950^{\circ}C$, the maximum value) in x = 0.3. The electrical conductivity was decreased in x = 0.4 because of the presence of the second phase in the grain boundaries. The lattice volume was contracted by increase of $Mn^{4+}$ ions and $Cu^{3+}$ ions in B-site according to increase of Sr content and the electrical conductivity was increased with increase of charge carriers which were involved in the hopping mechanism. $La_{1-x}Sr_xMn_{0.8}Cu_{0.2}O_{3-{\delta}}$(LSMCu)에서 Sr 함량에 따른 구조적 변화와 전기전도도에 대해 연구, 고찰하였다. EDTA citric complexing process(ECCP)로 페로브스카이트 구조를 갖는 $La_{0.8}Sr_{0.2}MnO_3$(LSM)와 $La_{1-x}Sr_xMn_{0.8}Cu_{0.2}O_3$($0.1{\leq}x{\leq}0.4$)을 제조하였다. Sr 함량이 증가할수록 격자상수와 격자부피는 감소하는 경향을 나타내었으며, 이는 Sr 함량이 증가함에 따라 B-site에서 증가하는 $Mn^{4+}$ 이온과 $Cu^{3+}$ 이온의 영향인 것으로 판단하였다. $0.1{\leq}x{\leq}0.3$ 범위의 조성에서 Sr 함량이 증가할수록 $500{\sim}1000^{\circ}C$에서 측정된 전기전도도는 증가하였고, x = 0.3 조성에서는 $750^{\circ}C$와 $950^{\circ}C$에서 각각 172.6 S/cm와 177.7 S/cm (최고값)를 나타내었다. 반면, x = 0.4 조성에서는 전기전도도가 감소하였는데 이는 입계에 발생한 산화물에 의한 영향으로 판단하였다. Sr 함량이 증가함에 따라 B-site에 존재하는 $Mn^{4+}$ 이온과 $Cu^{3+}$ 이온의 증가로 인해 격자수축이 발생하고, hopping mechanism에 관여하는 charge carrier들이 늘어나 전기전도도가 증가한 것으로 판단하였다.

심전도를 이용한 성별 추정 인공지능 프레임워크

류지승(Ji-Seung Ryu),이솔암(Sol-Am Lee),추유성(Yu-Seong Chu),이예린(Ye-rin Lee),강승영(Seung-young Kang),박영준(Young-Jun Park),고상백(Sang-Baek Koh),양세정(Se-Jung Yang) 대한전자공학회 2022 대한전자공학회 학술대회 Vol.2022 No.6

8 채널 심전도를 이용한 인공지능 기반 빈혈 진단 알고리즘

류지승(Ji-Seung Ryu),추유성(Yu-Seong Chu),한중훈(Jung-Hun Han),박영준(Young-Jun Park),이솔암(Sol-Am Lee),양세정(Se-Jung Yang) 대한전자공학회 2021 대한전자공학회 학술대회 Vol.2021 No.6

Acute Toxicity Test of Heavy Metals Using Korean Freshwater Shrimp, Neocardina denticulata

Jisung Ryu(류지승),Eun Kyoung Kim(김은경),Ye Ryoun Mun(문예륜),Kyunghee Choi(최경희),Hyun-Mi Kim(김현미) 환경독성보건학회 2007 한국독성학회 심포지움 및 학술발표회 Vol.- No.-

Cu가 도핑된 LSM의 구조분석과 열팽창특성 연구

노태민,류지승,김진성,정철원,이희수,Noh, Tai-Min,Ryu, Ji-Seung,Kim, Jin-Seong,Jeong, Cheol-Weon,Lee, Hee-Soo 한국결정성장학회 2011 한국결정성장학회지 Vol.21 No.4

이종 원자가를 가시는 Cu의 도핑이 LSM에 미치는 영향을 구조적인 분석과 열팽창계수를 통해서 고찰하였다. 고상반응을 이용하여 $La_{0.8}Sr_{0.2}Mn_{1-x}Cu_xO_3$($0{\leq}x{\leq}0.3$)음 제조하였으며, Cu의 도핑 함량에 따른 결정구조 및 열팽창계수를 확인하였다. Cu 함량이 증가함에 따라서 격자상수외 열팽창계수가 감소하는 경향을 나타냈지만, x = 0.3인 경우에는 증가 하였다. 이러한 격자상수와 열팽창계수의 변화는 Cu 이온의 B-site에서의 Mn 자리에 치환될 때 $0{\leq}x{\leq}0.2$의 범위에서는 $Cu^{3+}$의 존재로 인한 이온 반성의 감소에 의한 것으로 판단되었고, x=0.3인 경우에는 $Cu^{2+}$와 $Mn^{4+}$의 존재로 인한 산소 공공의 증가에 기인한 것이었다. The doping effect of Cu in the Sr-doped lanthan manganites (LSM) has been investigated in terms of structural analysis and thermal expansion coefficient (TEC). The $La_{0.8}Sr_{0.2}Mn_{1-x}Cu_xO_3$ ($0{\leq}x{\leq}0.3$) were prepared by solid state reaction method and their crystal structure and TEC were measured. A decrease in the lattice parameters and the TEC were observed with increase eu content, whereas they were decreased for x = 0.3. For $0{\leq}x{\leq}0.2$, the decrease of the lattice parameter and the TEC with increase Cu content were attributed to the reduction of ionic radius of Cu ions due to the presence of $Cu^{3+}$ ions. For x = 0.3, however, the increase was originated from the formation of oxygen vacancies due 10 the presence of $Cu^{2+}$ and $Mn^{4+}$.

Artificial Intelligence for Detection of Cardiovascular- Related Diseases from Wearable Devices: A Systematic Review and Meta-Analysis

이솔암,추유성,류지승,박영준,양세정,고상백 연세대학교의과대학 2022 Yonsei medical journal Vol.63 No.-

Purpose: Several artificial intelligence (AI) models for the detection and prediction of cardiovascular-related diseases, including arrhythmias, diabetes, and sleep apnea, have been reported. This systematic review and meta-analysis aimed to identify AI models developed for or applicable to wearable and mobile devices for diverse cardiovascular-related diseases. Materials and Methods: The searched databases included Medline, Embase, and Cochrane Library. For AI models for atrial fibrillation (AF) detection, a meta-analysis of diagnostic accuracy was performed to summarize sensitivity and specificity. Results: A total of 102 studies were included in the qualitative review. There were AI models for the detection of arrythmia (n=62), followed by sleep apnea (n=11), peripheral vascular diseases (n=6), diabetes mellitus (n=5), hyper/hypotension (n=5), valvular heart disease (n=4), heart failure (n=3), myocardial infarction and cardiac arrest (n=2), and others (n=4). For quantitative analysis of 26 studies reporting AI models for AF detection, meta-analyzed sensitivity was 94.80% and specificity was 96.96%. Deep neural networks showed superior performance [meta-analyzed area under receiver operating characteristics curve (AUROC) of 0.981] compared to conventional machine learning algorithms (meta-analyzed AUROC of 0.961). However, AI models tested with proprietary dataset (meta-analyzed AUROC of 0.972) or data acquired from wearable devices (meta-analyzed AUROC of 0.977) showed inferior performance than those with public dataset (meta-analyzed AUROC of 0.986) or data from in-hospital devices (meta-analyzed AUROC of 0.983). Conclusion: This review found that AI models for diverse cardiovascular-related diseases are being developed, and that they are gradually developing into a form that is suitable for wearable and mobile devices.

전산화 공정에 의한 microcystin 용출 및 고도처리에 의한 제거 특성

염훈식,손희종,류지승,정은영,김경아 대한환경공학회 2019 대한환경공학회지 Vol.41 No.10

목적 : 하절기 고농도의 Microcystis sp. 함유 원수가 정수장으로 유입시에 전산화 공정에서의 microcystin (MCs) 용출과 후단의 고도 정수처리 공정에서 용출된 MCs의 제거 가능성 평가가 목적이다. 방법 : 고농도 Microcystis sp. 함유원수(400,000 cells/mL)를 이용하여 전염소와 전오존 처리에 의한 MCs 용출 특성을 평가하였으며, 후단의 고도 정수처리 공정인 O3, O3/H2O2, UV/H2O2 및 BAC 공정에서의 전산화 처리에 의해용출된 MCs 제거 특성을 평가하였다. 결과 및 토의 : 전염소 투입농도가 증가할수록 수중으로 용출된 MCs 농도는 급격히 증가하다가 염소 투입농도 5 mg/L 이상에서는 감소하였고, 용출된 MCs의 대부분은 MC-RR (57∼86%)과 MC–LR (11∼29%)이 차지하였다. 전염소 처리 이후 전오존 처리공정에서 오존 투입농도가 증가할수록 수중의 MCs 농도는 처리 전에 비해 수∼수십배 정도 증가하였으나, 전염소를 3 mg/L 이상으로 처리한 경우에는 오존 투입농도가 증가할수록 MCs가 급격히제거되었다. 전산화 처리 후, 응집-침전 처리수 중의 MCs 농도가 처리 전에 비하여 2배 이상 급격히 증가였으며, 침전공정 동안 산화제에 손상된 Microcystis 조체에서 MCs가 지속적으로 유출되었다. 후산화 공정에서는 O3과O3/H2O2 공정이 UV/H2O2 공정에 비해 MCs 제거에 효과적이었고, O3과 O3/H2O2 공정에서 1 mg/L 이상으로 O3을투입한 경우 MCs가 100% 제거되었다. BAC 공정에서는 MCs 유입농도가 각각 0.8 μg/L와 2.8 μg/L일 때 EBCT 15분에서 각각 100%와 93% 제거되었으며, MC-RR에 비해 MC-LR의 생물분해 제거능이 낮았다. 고농도의 MCs가유입되거나 MC–LR의 구성비율이 높을 경우에는 BAC 공정의 EBCT를 증가시켜 운전할 필요가 있었다. 결론 : 고농도 Microcystis sp. 함유 원수를 전산화 처리하면 고농도의 MCs이 용출되었으나 후단의 O3, O3/H2O2, UV/H2O2 및 BAC 공정과 같은 고도 정수처리 공정에서 제거가 가능하였다. 특히, UV-AOP 공정에 비해 O3 공정에의한 MCs 제거율이 높았으며, BAC 공정에서도 EBCT 15분의 조건에서는 93∼99%의 MCs가 제거되었다. Microcystis sp.가 번성하는 시기에 응집/침전 공정의 효율 증진을 위해 전산화 공정을 적용하는 정수장에서는 후단에 O3/BAC 공정을 적용할 경우 MCs 제거에 매우 효과적으로 나타났다. Objectives : The objectives of this study were to evaluate the characteristics of microcystins (MCs) release form Microcystis sp. in surface water during pre-oxidation process using chlorine and ozone and it’s removal by advanced water treatment process as post process when raw water containing high Microcystis sp. is introduced into the water treatment plant. Methods : Raw water which had contained over 400,000 cells/mL of Microcystis sp. were used to evaluate the characteristics of MCs released from Microcyctis sp. and chlorination (Cl2) and ozonation (O3) were used as pre-oxidation process and O3, O3/H2O2, UV/H2O2 and biological activated carbon (BAC) were used as post oxidation process. Results and Discussion : As the concentration of chlorine increased, the concentration of released MCs in the water increased, but decreased when higher than 5 mg/L of chlorine dosage. Released MCs were consisted of almost MC-RR (57∼86%) and MC–LR (11∼29%). In the ozone treatment after prechlorination process, the MCs concentration was increased by several fold to dozen fold to compare before ozonation. However, when chlorine dosage was over 3 mg/L, MCs were rapidly removed as the ozone concentration increased. The MCs concentration of flocculation/sedimentation treated sample after the pre-oxidation was increased more than two times before treatment, the MCs was continuously released during the coagulation/sedimentation process from the damaged Microcystis sp. due to the prior oxidation process. In the post-oxidation process, O3 and O3/H2O2 processes were more effective for removing MCs than the UV/H2O2 process, and O3 and O3/H2O2 processes removed 100% of the MCs when O3 was added above 1 mg/L. 100% and 93% were removed respectively at 15 minutes of EBCT (empty bed contact time) in the BAC process, when the MCs concentrations of influent were 0.8 μg/L and 2.8 μg/L. The biodegradability of MC-LR was lower than that of MC-RR. It was necessary to increase the EBCT of the BAC process when the concentrations of MCs or the ratio of MC-LR were high. Conclusions : Although, pre-oxidation treatment to the raw water containing high concentration of Microcystis release higher MCs concentration in the oxidized water, that can be removed by post O3, O3/H2O2, UV/H2O2 and BAC processes. The removal rate of MCs by O3 process was higher than that of UV-AOP process, and 93∼99% of MCs removed with 15 min of EBCT in BAC process. In the drinking water treatment plant where the pre-oxidation process is applied to improve the efficiency of the flocculation/sedimentation process during the blooming season of Microcystis sp., O3/BAC process after the flocculation/sedimentation process is recommendable to MCs remove.

Distribution Characteristics of Natural Radioactive Materials in Small-scale Water Supply Systems

정태욱,유상원,류지승,송복주,최진택 환경독성보건학회 2021 한국독성학회 심포지움 및 학술발표회 Vol.2021 No.10

Dysprosium과 Erbium이 동시 첨가된 X7R MLCC용 페로브스카이트 BaTiO₃의 전기적특성과 온도안정성

노태민,김진성,류지승,이희수,Noh, Tai-Min,Kim, Jin-Seong,Ryu, Ji-Seung,Lee, Hee-Soo 한국세라믹학회 2011 한국세라믹학회지 Vol.48 No.4

The effects of $Dy_2O_3$ and $Er_2O_3$ co-doping on electrical properties and temperature stability of barium titanate ($BaTiO_3$) ceramics were investigated in terms of microstructure and structural analysis. The dielectric constant and the insulation resistance (IR) of 0.7 mol% $Dy_2O_3$ and 0.3 mol% $Er_2O_3$ co-doped dielectrics had about 60% and 20% higher than the values of undoped one, respectively, and the temperature coefficient of capacitance (TCC) met the X7R specification. The addition of $Dy_2O_3$ contributed to electrical properties caused by increase of tetragonality; however, preferential diffusion of $Dy^{3+}$ ions toward A site in $BaTiO_3$ grain exhibited an adverse effect on temperature stability by grain growth. On the other hand, The $Er_2O_3$ addition in $BaTiO_3$ could affect the TCC behavior and the IR with suppression of grain growth caused by reinforcement of grain boundary and electrical compensation. Therefore, the enhanced electrical properties and temperature stability through the co-doping could be deduced from the increase of tetragonality and the suppression of grain growth.