멀티 모달 지도 대조 학습을 이용한 농작물 병해 진단 예측 방법

이현석,여도엽,함규성,오강한,Hyunseok Lee,Doyeob Yeo,Gyu-Sung Ham,Kanghan Oh 대한임베디드공학회 2023 대한임베디드공학회논문지 Vol.18 No.6

With the wide spread of smart farms and the advancements in IoT technology, it is easy to obtain additional data in addition to crop images. Consequently, deep learning-based crop disease diagnosis research utilizing multimodal data has become important. This study proposes a crop disease diagnosis method using multimodal supervised contrastive learning by expanding upon the multimodal self-supervised learning. RandAugment method was used to augment crop image and time series of environment data. These augmented data passed through encoder and projection head for each modality, yielding low-dimensional features. Subsequently, the proposed multimodal supervised contrastive loss helped features from the same class get closer while pushing apart those from different classes. Following this, the pretrained model was fine-tuned for crop disease diagnosis. The visualization of t-SNE result and comparative assessments of crop disease diagnosis performance substantiate that the proposed method has superior performance than multimodal self-supervised learning.

수소전기상용차 냉각순환시스템용 고유량 제어 밸브 해석 설계

이현석(Hyunseok Lee),배석정(Sukjung Bae),허형석(Hyungseok Heo),박찬진(Chanjin Park) 한국자동차공학회 2023 한국자동차공학회 부문종합 학술대회 Vol.2023 No.5

As environmental and resource concerns escalate, eco-friendly vehicles have gained momentum in the global automobile market. Among them, fuel cell electric vehicles (FCEVs) are becoming increasingly popular due to their higher loading capacity, shorter charging times, and longer mileage compared to battery electric vehicles. However, increasing FCEV’s market competitiveness requires improving the efficiency of the cooling circulation system. In particular, in FCEV’s power electronics (PE) system, the coolant flow rate requires a very high discharge flow rate of more than 200 L/min, so the development of an electronic valve for flow control to manage this high flow rate is necessary. This study focuses on the computational fluid dynamics (CFD) flow analysis of valve designed to control high flow rates in electrical component cooling circulation system. Specifically, the flow resistance characteristics according to valve opening and flow conditions were analyzed. The results show that the design to minimize the interference area inside the valve can reduce the pressure drop somewhat. Furthermore, vertical flow path setting has been shown to be more effective than horizontal flow path setting. In addition to flow performance, design plans to expand the flow path diameter requires consideration from various perspectives. This research contributes to improving the efficiency of FCEVs and supports the market competitiveness of FCEVs as a promising eco-friendly alternative to traditional gasoline-powered vehicles

선의 의무와 악의 권리 : 1970년대 사회적 상상력의 두 양상

이현석(Lee Hyunseok) 한국현대문학회 2014 한국현대문학연구 Vol.0 No.44

SDR용 기저대역 프로세서를 위한 프로그래밍 모델

이현석(Hyunseok Lee),이준환(Joonhwan Yi),오혁준(Hyukjun Oh) 대한전자공학회 2010 電子工學會論文誌-SD (Semiconductor and devices) Vol.47 No.7

이 논문은 SDR 시스템용으로 개발된 기저대역 프로세서인 SODA-Ⅱ를 활용하는데 필요한 프로그래밍 모델에 대한 것이다. SODA-Ⅱ는 4개의 프로세서로 구성되는 멀티코어 시스템으로 한 코어에는 SIMD 데이터패스와 직렬 데이터패스가 모두 구현되어 있어 벡터 연산과 직렬 연산이 혼재하는 기저대역 신호처리 동작에 적합하다. SODA-Ⅱ에 대한 프로그래밍 모델은 C 언어 라이브러리 형태를 가진다. 라이브러리 함수가 SODA-Ⅱ의 SIMD 데이터패스를 구동시키는데 필요한 세부적인 제어동작을 모두 처리하므로 사용자는 SIMD 데이터패스 구조에 대한 자세한 이해 없이 기저대역 신호처리 알고리즘을 구현할 수 있다. 이 논문에서는 기저대역 신호처리의 핵심 연산들이 SODA-Ⅱ에서 어떤 형태로 구현되는지 설명하고 응용의 예로 W-CDMA 다중 경로 탐색기와 OFDM 복호기 동작을 SODA-Ⅱ에서 구현한 결과를 살펴본다. This paper discusses the programming model of SODA-Ⅱ that is a baseband processor for software defined radio (SDR) systems. Signal processing On-Demand Architecture Ⅱ (SODA-Ⅱ) is an on-chip multiprocessor architecture consisting of four processor cores and each core has both an wide SIMD datapath and a scalar datapath. This architecture is appropriate for baseband processing that is a mixture of vector computations and scalar computations. The programming model of the SODA-Ⅱ is based on C library routines. Because the library routines hide the details of complex SIMD datapath control procedures, end users can easily program the SODA-Ⅱ without deep understanding on its architecture. In this paper, we discuss the details of library routines and how these routines are exploited in the implementation of baseband signal processing algorithms. As application examples, we show the implementation result of W-CDMA multipath searcher and OFDM demodulator on the SODA-Ⅱ.

연료전지 촉매의 성능 및 내구성 확보를 위한 전자빔 반응기 냉각 성능 평가

이현석(Hyunseok Lee),배석정(Sukjung Bae),허형석(Hyungseok Heo),양대수(Daesoo Yang),윤영철(Yeongcheol Yoon) 한국자동차공학회 2022 한국자동차공학회 학술대회 및 전시회 Vol.2022 No.11

Fuel cell catalyst is used to activate oxygen reduction reactions in the reduction electrode, which is a core material for improving power generation efficiency in the hydrogen fuel cell field. The electron beam process is environmentally friendly amongst the fuel cell catalyst manufacturing methods, in which metal ions in the solution is reduced without using reduction agent. The electron beam synthesis process is performed in a room temperature environment, and reaction heat is generated while receiving electrons irradiated from electron beam and performing the reduction process. In this study, a reactor has been evaluated with cooling performance to cool down the reaction heat generated. The reactor evaluation has been performed by measuring the temperatures of the aqueous precursor solution at time points, e.g.,initial stage before the electron beam synthesis process, 20 minutes after the electron beam irradiation, and 10 minutes after cooling after the electron beam irradiation is terminated. As the result of the evaluation, it is determined that a sufficiently low temperature of the solution after electron beam process can be acquired according to the change in the electron beam irradiation and coolant conditions.

K9 자주포 동력장치용 연료냉각기 열유동 성능 해석 설계

이현석(Hyunseok Lee),배석정(Sukjung Bae),홍성목(Seongmok Hong),이호남(Honam Lee),박천명(Cheonmyung Park) 한국자동차공학회 2023 한국자동차공학회 부문종합 학술대회 Vol.2023 No.5

The K9 self-propelled artillery is developed with independent Korean technology, and has been exported to various countries in Europe and Asia due to its exceptional performance and practical experience. However, the coolers used in the K9 self-propelled artillery power unit are all imported, which limits the potential for exports. To address this issue, we aim to develop and localize components that can be applied to the K9 self-propelled artillery power units. In this study, we developed a 1D performance analysis program to facilitate the alternative development of fuel coolers. The program uses design variables of the fuel coolers shape and operating conditions to calculate analysis results. We conducted a parametric study of a fuel cooler using the program, varying the number of fuel tubes and offset fin pitch. Our analysis showed that as the number of fuel tubes increases, the amount of heat dissipation increases while the pressure drop of fuel and air decreases. Furthermore, as the offset fin pitch increases, the heat transfer area decreases, the flow path increases, and the heat dissipation and pressure drop on the fuel side decrease.

DMFT 연관지표를 이용한 치아별 우식 양상 및 치아우식증 경험군과 고위험군의 위험요인 분석

이현석 ( Hyunseok Lee ),안소연 ( Soyoun An ) 대한예방치과·구강보건학회 2020 大韓口腔保健學會誌 Vol.44 No.4

Objectives: One of the main causes of tooth loss in Korea is dental caries, a chronic disease affecting individuals of all ages worldwide. The average decayed, missing, and filled teeth (DMFT) index, a measure of the caries experience of the population, has been stagnating in Korea for a number of years. The purpose of this study was to investigate the pattern of caries prevalence by tooth type, and to identify the characteristics and risk factors of the specific affected caries (SaC) and significant caries (SiC) groups in Korea’s 12-year-old children. Data were obtained from the 2018 Children’s Oral Health Survey. Methods: Data from a total of 22,303 subjects were included in the study. We grouped the data according to two DMFT-related indices, the SaC index, which includes all subjects who have experienced a carious lesion, and the SiC index, which includes the top one-third of the population by DMFT. We then analyzed the sociodemographic variables and oral health behaviors seen in these groups. Results: The average DMFT index for all the 12-year-old children was 1.89, and that of those in the SaC and SiC groups was 3.37 and 4.86, respectively. The teeth that were found to be most likely to develop caries were the mandibular and maxillary first molars, and the tooth associated with the highest mean DMFT index was the mandibular first premolar. Among the variables analyzed, perceived oral health status was the most influential variable in the SaC and SiC groups, followed by gender, and then the presence or absence of calculus. Household income was not a statistically significant variable. Conclusions: The results of this study revealed the characteristics common to 12-year-old children who are vulnerable to caries. This will provide valuable information when planning dental disease management projects.

비구속 강구를 이용한 전방향 구동시스템

이현석(Hyunseok Lee),장홍석(Hongseok Jang),이광훈(Kwanghoon Lee),박종규(Jongkyu Park) 대한기계학회 2012 대한기계학회 춘추학술대회 Vol.2012 No.11

In this paper, a new omni-directional driving system with one spherical wheel is proposed. This system is able to overcome existing driving systems with structural limitations such as vertical, horizon and diagonal movement. This driving system was composed of two stepping motors and a spherical wheel covered by ball bearing. An own ball bearing was designed for settled rotation and smooth change of direction of a spherical wheel. One of the stepping motors is for driving the spherical wheel. This spherical wheel is stable because of the support of ball bearing. And the other enables to move to ways which want while it rotates based on the central axis. The ATmega128 chip is used for the control of two stepping motors. To verify the proposed system, driving experiments was executed in variety of environments. Finally, the performance and the validity of the omni-directional driving system was confirmed.

Enhancement of room temperature formability of strip cast AZ31 alloy sheet

Hyunseok Lee(이현석),W. Bang(방원규),Kiho Yun(윤기호),Dongkyun Choo(추동균),Ohduck Kwon(권오덕) 한국소성가공학회 2012 마그네슘 심포지엄 Vol.2012 No.11

투명 박막 리튬이차전지를 위한 LiNiPO₄ 박막의 광학 및 전기화학적 특성

이현석 ( Hyunseok Lee ),( Narendra S Parmar ),김광범 ( Kwang-bum Kim ),최지원 ( Ji-won Choi ) 한국센서학회 2018 센서학회지 Vol.27 No.1

Transparent olivine LiNiPO4 thin films on sapphire substrates were fabricated by radio frequency (RF) magnetron sputtering. The Xray diffraction patterns show these thin films have the phase of LiNiPO₄ with an ordered olivine structure indexed to the orthorhombic Pmna space group. LiNiPO₄ thin films deposited on sapphire substrates exhibit transmittance of about 83 %. It was confirmed that the LiNiPO₄ thin film exhibits a high potential of 5 V-class.