• Korean Journal of Remote Sensing
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• v.39 no.6_2
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• pp.1565-1576
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• 2023

An atmospheric correction algorithm based on the radiative transfer model is required to obtain remote-sensing reflectance (R_rs) from the Geostationary Ocean Color Imager-II (GOCI-II) observed at the top-of-atmosphere. This R_rs derived from the atmospheric correction is utilized to estimate various marine environmental parameters such as chlorophyll-a concentration, total suspended materials concentration, and absorption of dissolved organic matter. Therefore, an atmospheric correction is a fundamental algorithm as it significantly impacts the reliability of all other color products. However, in clear waters, for example, atmospheric path radiance exceeds more than ten times higher than the water-leaving radiance in the blue wavelengths. This implies atmospheric correction is a highly error-sensitive process with a 1% error in estimating atmospheric radiance in the atmospheric correction process can cause more than 10% errors. Therefore, the quality assessment of R_rs after the atmospheric correction is essential for ensuring reliable ocean environment analysis using ocean color satellite data. In this study, a Quality Assurance (QA) algorithm based on in-situ R_rs data, which has been archived into a database using Sea-viewing Wide Field-of-view Sensor (SeaWiFS) Bio-optical Archive and Storage System (SeaBASS), was applied and modified to consider the different spectral characteristics of GOCI-II. This method is officially employed in the National Oceanic and Atmospheric Administration (NOAA)'s ocean color satellite data processing system. It provides quality analysis scores for R_rs ranging from 0 to 1 and classifies the water types into 23 categories. When the QA algorithm is applied to the initial phase of GOCI-II data with less calibration, it shows the highest frequency at a relatively low score of 0.625. However, when the algorithm is applied to the improved GOCI-II atmospheric correction results with updated calibrations, it shows the highest frequency at a higher score of 0.875 compared to the previous results. The water types analysis using the QA algorithm indicated that parts of the East Sea, South Sea, and the Northwest Pacific Ocean are primarily characterized as relatively clear case-I waters, while the coastal areas of the Yellow Sea and the East China Sea are mainly classified as highly turbid case-II waters. We expect that the QA algorithm will support GOCI-II users in terms of not only statistically identifying R_rs resulted with significant errors but also more reliable calibration with quality assured data. The algorithm will be included in the level-2 flag data provided with GOCI-II atmospheric correction.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.08a
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• pp.311-312
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• 2012

본 발표에서는 광학적 분석 시스템에 적용 가능한 발광소자(광원)과 수광소자(광센서)를 집적화시키는 모듈(수 발광 집적모듈) 기술을 제시하고자 한다. 이러한 수-발광 집적모듈은 다양한 응용 분야에 적용 될 수 있다. 예를 들어, 광신호 감지를 위한 광통신용 송-수신 모듈(optical communication), 의료/진단 분야에서 단백질/DNA/박테리아 등의 검출 및 분석에 관한 바이오 센서(bio-sensor), 그리고 대기(가스)/수질 모니터링에 관한 환경센서 등 매우 광범위한 분야에 해당되는 요소 기술이라 할 수 있다. 특히, 이들 분야들 중 바이오 물질을 분석하고 검출하는 광학적 바이오 센서 기술은 높은 경제적 가치와 산업적 성장 잠재력으로 인해 오랫동안 활발한 연구가 진행되어 오고 있다. 이러한 광학적 바이오 센서에서 가장 범용적인 방법 중 하나가 항온-항체 면역반응을 기반으로 하는 형광 검출(fluorescence detection) 기법이다. 이러한 시스템은 전체적으로 광원, 광학계, 그리고 센서로 구성되는데 기존에 일반적으로 사용되고 있는 형광 현미경의 경우는 민감도가 우수하다는 장점은 있으나 상당히 고가이고 부피가 크며 복잡한 광학구성으로 이루어져 있다는 한계점을 가지고 있다. 이러한 맥락에서 고민감도를 확보하면서 휴대성, 고속처리, 저가 등의 특성을 가진 시스템에 대한 요구가 갈수록 증가하고 있다. 이를 해결하기 위한 핵심기술 중의 하나가 수-발광 부분을 집적화 시키는 기술이라 할 수 있다. 본 연구에서는 바이오 센서 기술의 하나로서 형광을 측정하여 혈액내의 진단 지표인자를 검출할 수 있는 휴대용 혈액진단기기에 적용되는 소형 수 발광 집적 모듈을 개발하였다. 혈액내의 검출 성분의 양에 따라 형광의 세기가 변화하게 됨으로써 정량적인 검출이 가능한 원리이다. 모듈의 구조는 크게 광원(발광소자), 광학계, 그리고 광센서(수광소자) 세 영역으로 나누어 진다. 광원은 635 nm 적색 레이저다이오드로서 형광체(Alexa Fluor 647/발광파장: 668 nm)를 여기 시키는 기능을 하며 장착된 볼렌즈 의해 샘플의 형광체 영역으로 집광된다. 광학계는 크게 시준렌즈(collimating lens)와 광학필터로 구성됨으로써 샘플로부터 발생되는 광을 적절하게 수광소자로 전달하는 기능을 하게 된다. 여기서 광학필터의 경우는 기본적으로 Distributed Bragg's Reflector(DBR) 구조로써 실리콘(Si) 포토다이오드 상부에 모노리식(monolithic)하게 형성되며 검출 샘플로부터 진행되는 레이저 광(잡음의 주원인)은 차단하고 형광(광신호)만 통과 시키는 기능을 하게 된다. 따라서 신호 대 잡음비(S/N ratio)를 향상시키기 위해서는 정밀한 광 필터링 기능이 요구됨으로써 박막의 세밀한 공정 조건과 구조적-광학적 특성 분석이 수행되었다. 마지막으로 포토다이오드 소자는 일반적인 구조 이외에 중앙에 원형 구멍이 형성된 특별한 구조가 적용된다. 이것은 포토다이오드 구조에 변화를 줌으로써 모듈 구조를 효율적으로 응용할 수 있다는 의미를 갖는다. 또한 포토다이오드의 전기적-광학적 측정 분석을 통해 잡음 및 감도 특성이 세부적으로 조사되며 형광신호를 효과적으로 측정할 수 있음을 확인하였다. 최종적으로 제작된 모듈은 약 $1{\times}1{\times}1cm^3$ 내외 정도의 크기를 갖는다. 요약하자면 본 발표에서는 광학적 바이오센서에 적용할 수 있는 소형 수-발광 소자 집적모듈을 소개한다. 전체 모듈 설계는 최소한의 부피를 가짐과 동시에 측정의 정밀성을 향상시키는데 초점을 맞추어 진행하였다. 세부요소인 광학필터와 포트다이오드의 경우 잡음 및 민감도에 미치는 중요성 때문에 세밀한 공정 및 특성분석이 수행되었다. 결론적으로 독자적인 설계 및 공정을 통해 휴대성 및 정밀성 등의 목적에 부합한 경쟁력 있는 수-발광 소자 집적모듈 제작 기술을 확보하였다.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.08a
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• pp.375-375
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• 2012

Graphene is a sp2-hybridized carbon sheet with an atomic-level thickness and a wide range of graphene applications has been intensely investigated due to its unique electrical, optical, and mechanical properties. In particular, hybrid graphene structures combined with various nanomaterials have been studied in energy- and sensor-based applications due to the high conductivity, large surface area and enhanced reactivity of the nanostructures. Conventional metal-catalytic growth method, however, makes useful applications difficult since a transfer process, used to separate graphene from the metal substrate, should be required. Recently several papers have been published on direct graphene growth on the two dimensional planar substrates, but it is necessary to explore a direct growth of hierarchical nanostructures for the future graphene applications. In this study, uniform graphene layers were successfully synthesized on highly dense dielectric nanowires (NWs) without any external catalysts. We also demonstrated that the graphene morphology on NWs can be controlled by the growth parameters, such as temperature or partial pressure in chemical vapor deposition (CVD) system. This direct growth method can be readily applied to the fabrication of nanoscale graphene electrode with designed structures because a wide range of nanostructured template is available. In addition, we believe that the direct growth growth approach and morphological control of graphene are promising for the advanced graphene applications such as super capacitors or bio-sensors.

• Journal of the Korea Society of Computer and Information
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• v.25 no.3
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• pp.243-250
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• 2020

In this paper, we propose an effective software education scheme for universities. The key idea of this software education scheme is to analyze software curriculum of QS world university rankings Top 10, SW-oriented university, and regional main national university. And based on the results, we propose five improvements for the effective SW education method of universities. The first is to enhance the adaptability of the industry by developing courses based on the SW developer's job analysis in the curriculum development process. Second, it is necessary to strengthen the curriculum of the 4th industrial revolution core technologies(cloud computing, big data, virtual/augmented reality, Internet of things, etc.) and integrate them with various fields such as medical, bio, sensor, human, and cognitive science. Third, programming language education should be included in software convergence course after basic syntax education to implement projects in various fields. In addition, the curriculum for developing system programming developers and back-end developers should be strengthened rather than application program developers. Fourth, it offers opportunities to participate in industrial projects by reinforcing courses such as capstone design and comprehensive design, which enables product-based self-directed learning. Fifth, it is necessary to develop university-specific curriculum based on local industry by reinforcing internship or industry-academic program that can acquire skills in local industry field.

• Journal of Biosystems Engineering
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• v.36 no.2
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• pp.79-88
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• 2011

The purpose of this study was to analyze power requirement of an agricultural tractor by major field operations. First a survey was conducted to obtain annual usage ratio of agricultural tractor by field operation. Plowing, rotary tillage, and loader operations were selected as major field operations of agricultural tractor. Second, a power measurement system was constructed with strain-gauge sensors to measure torque of four driving axles and a PTO axle, speed sensors to measure rotational speed of the driving axles and an engine shaft, pressure sensors to measure pressure of hydraulic pumps, an I/O interface to acquire the sensor signals, and an embedded system to calculate power requirement. Third, the major field operations were experimented under fields with different soil conditions following planned operation paths. Power requirement was analyzed during the total operation period consisted of actual operation period (plowing, rotary tillage, and loader operations) and period before and after the actual operation (3-point hitch operating, forward and reverse driving, braking, and steering). Power requirement of tractor major components such as driving axle part, PTO part, main hydraulic part, and auxiliary hydraulic part were measured and calculated to determine usage ratio of agricultural tractor power. Results of averaged power requirement for actual field operation and total operation were 23.1 and 17.5 kW, 24.6 and 19.1 kW, and 14.9 and 8.9 kW, respectively, for plowing, rotary tillage, and loader operations. The results showed that rotary tillage required the greatest power among the operations. Averaged power requirement of driving axles, PTO axle, main hydraulic part, and auxiliary part during the actual field operation were 8.1, 7.8, 3.4, and 1.5 kW, respectively, and the total requirement power was about 70 % (20.8 kW) of the rated power. Averaged power requirement of driving axles, PTO axle, main hydraulic, and auxiliary hydraulic for the total operation period were 6.5, 6.0, 2.1, 0.9 kW, respectively, and total requirement power was about 52 % (15.5 kW) of the rated power. Driving axles required the greatest amount of power among the components.

• Journal of Biosystems Engineering
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• v.36 no.4
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• pp.243-251
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• 2011

Purpose of this study was to analyze power requirement of an agricultural tractor for baler operation. First, a power measurement system was developed and installed in a 75 kW agricultural tractor. Strain-gages with a telemetry system were used to measure torques of transmission and PTO input shafts. An engine tachometer was used to measure rotational speed of transmission and PTO input shafts. The measurement system also included pressure sensors to measure pressure of hydraulic pumps, an I/O interface to acquire the sensor signals, and an embedded system to determine power requirements. Second, field experiments were conducted at two PTO speed levels, and proportion of utilization ratio of rated engine power and power consumption of major parts (transmission input shaft, PTO input shaft, main hydraulic pump, and auxiliary hydraulic pump) were analyzed. Results of usage proportion of engine power for PTO speed level 1 and 2 were 4.1 and 2.2%, 31.5 and 16.3%, 49.6 and 59.7%, 14.4 and 20.8%, and 0.4 and 1.0%, respectively, for ratio of measured engine power to rated engine power of less than 25%, 25 ~ 50%, 50 ~ 75%, 75 ~ 100%, and greater than 100%. The results showed that the usage proportion increased in the range with the ratio of power requirement to rated engine power of over than 50% when the PTO gear was shifted from P1 to P2. Averaged engine power requirement for baling operation, tying and discharging operation, and total operation were 43.3, 37.3, and 42.0 kW and 49.0, 37.0, and 47.4 kW, respectively, for PTO speed level 1 and 2. Paired t-test showed significant difference in power consumption of engine, transmission input shaft, and PTO input shaft for different PTO speed levels. Therefore, the power consumption of engine for baler operation increased when the PTO gear was shifted from P1 to P2. It was indicated that the power requirement of tractor was affected by the PTO rotational speed for baler operation.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.35 no.1
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• pp.38-50
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• 2013

Purpose: The aim of this study is to evaluate the effect and potential of electron beam (E-beam) irradiation treatment to the synthetic bony mixtures composed of hydroxyapatite (HA; Bongros$^{(R)}$, Bio@ Co., Korea) and tricalcium phosphate (${\beta}$-TCP, Sigma-Aldrich Co., USA), mixed at various ratios and of type I collagen (Rat tail, BD Biosciences Co., Sweden) as an organic matrix. Methods: We used 1.0~2.0 MeV linear accelerator and 2.0 MeV superconductive linear accelerator (power 100 KW, pressure 115 kPa, temperature $-30{\sim}120^{\circ}C$, sensor sensitivity 0.1~1.2 mV/kPa, generating power sensitivity 44.75 mV/kPa, supply voltage $5{\pm}0.25$ V) with different irradiation dose, such as 1, 30 and 60 kGy. Structural changes in this synthetic bone material were studied in vitro, by scanning electron microscopy (SEM), elementary analysis and field emission scanning electron microscope (FE-SEM), attenuated total reflection (ATR), and electron spectroscopy for chemical analysis (ESCA). Results: The large particular size of HA was changed after E-beam irradiation, to which small particle of TCP was engaged with organic collagen components in SEM findings. Conclusion: The important new in vitro data to be applicable as the substitutes of artificial bone materials in dental and medical fields will be able to be summarized.

• Journal of Life Science
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• v.30 no.10
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• pp.835-843
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• 2020

Obesity, the world's leading metabolic disease, is a serious health problem in both industrialized and developing countries. Natural substances are of great interest in preventative medicine, especially in the field of metabolic syndromes-from insulin resistance to obesity and diabetes. In the present study, we investigated the effect of A. pullulans SM-2001 Extract (Polycan^®) on the adipocyte differentiation of 3T3-L1 preadipocytes and the anti-obesity effect of 3T3-L1 adipocytes. Although β-glucan has been found to have health benefits in the regulation of the immune system and blood cholesterol levels, its role in obesity has not been fully investigated. Polycan^® suppressed lipid accumulation and glycerol-3-phosphate dehydrogenase (GPDH) activity without affecting cell viability in 3T3-L1 preadipocytes and adipocytes. Polycan^® also inhibited cellular lipid accumulation through down-regulation of transcription factors, such as PPARγ and C/EBPα, and induced dose-dependent phosphorylation of AMP-activated protein kinase (AMPK)-a cellular energy sensor-while the total AMPK protein content remained unchanged. Taken together, this shows that the activation of AMPK by Polycan^® in adipocytes plays a critical role in Polycan^®-induced inhibition of adipocyte differentiation. Our results show that Polycan^® has an anti-obesity action in vitro, suggesting a potential novel preventative agent for obesity and other metabolic diseases.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.12 no.6
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• pp.672-680
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• 2019

This paper proposes "A Smart Farm Environment Optimization and Yield Prediction Platform based on IoT and Deep Learning" which gathers bio-sensor data from farms, diagnoses the diseases of growing crops, and predicts the year's harvest. The platform collects all the information currently available such as weather and soil microbes, optimizes the farm environment so that the crops can grow well, diagnoses the crop's diseases by using the leaves of the crops being grown on the farm, and predicts this year's harvest by using all the information on the farm. The result shows that the average accuracy of the AEOM is about 15% higher than that of the RF and about 8% higher than the GBD. Although data increases, the accuracy is reduced less than that of the RF or GBD. The linear regression shows that the slope of accuracy is -3.641E-4 for the ReLU, -4.0710E-4 for the Sigmoid, and -7.4534E-4 for the step function. Therefore, as the amount of test data increases, the ReLU is more accurate than the other two activation functions. This paper is a platform for managing the entire farm and, if introduced to actual farms, will greatly contribute to the development of smart farms in Korea.

• 한국벤처창업학회:학술대회논문집
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• 2008.04a
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• pp.143-178
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• 2008

This study is to look into the spin-off ventures which was incorporated based on the technology developed by public research institute, but underwent difficulties confronted during the development stages focused on the growth process and the factors contributed to their success. The case study was conducted with i-Sense Co., Ltd. which is a ventures organized by professors as a form of research based spin-off venture. i-Sense Co., Ltd. is a new-technology based ventures to produce self-tester for blood sugar level which was incorporated by Prof. Cha, Keun-sik and Prof. Nam, Hak-hyun of Department of Chemistry in Kwangwoon University along with the graduate course students of the Research Laboratory of the University. The two professors operated the Chemical Sensor Research Center at the Kwangwoon University where they produced many preliminary research outputs related with bio-sensors. They also executed the service works at the specialized company they established for research development to make research fund. They established i-Sense Co., Ltd. with the aim to carry out the research they want to. But contrary to the initial intention of the founders of the company, i-Sense Co., Ltd. has grown up as manufacturing company which produces and sells the self-tester for blood sugar level and is expected to be listed by Initial Public Offering (IPO) on the KOSDAQ in 2008. This study is to analyze the foundation and the growth process of i-Sense Co., Ltd. as successful research based spin-off ventures, to find out the factors contributed to their success by enabling them to overcome the difficulties experienced during the growth process, and eventually to provide with suggestive meanings in policy and practical point of view that leaded the research based spin-off ventures to success.