• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2008.05a
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• pp.495-498
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• 2008

This paper describes design of a real-time, wearable reflectance pulse oximetry which is based Wireless Sensor Network. For the purpose of continuously monitoring vital signs of a human, wearable reflectance pulse oximetry is built into a wrist type that can be obtained $SpO_2$ value of patient unobtrusively. This designed $SpO_2$ module is based on a low-power 8 bit ATmega128L microcontroller operating in 3V. Low power operating $SpO_2$ module was integrated to wireless sensor node for user's health monitoring. This paper is focused on the successful integration of all these components into wearable reflectance pulse oximetry and evaluates its ability to measure patient' $SpO_2$ value. Information from this sensor was wirelessly transmitted to a base-station for storage and display purposes.

• Journal of Sensor Science and Technology
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• v.9 no.3
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• pp.203-207
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• 2000

The sensitivity of ISFET glucose sensor is improved by employing amperometric actuation method. However, this method takes long time to recover the primary output voltage after measurement because of slow migration of the hydrogen ion between internal and external sensing membranes. Consequently, such a recovery-time delaying problem is one of obstacles to a practical use. In this paper, a new method is proposed to control the concentration of hydrogen ion in internal membrane, which applies a reduction potential to the working electrode for supplying hydroxide ion. Experimental results show that the recovery-time was reduced within 2 minute against decades minute of conventional method.

• The Journal of the Korea institute of electronic communication sciences
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• v.17 no.4
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• pp.679-686
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• 2022

In this paper, we implemented an algae removal device that recognizes and removes algae existing in water using Raspberry Pi camera and DO (Dissolved Oxygen) sensor. The Raspberry Pi board recognizes the color of green algae by converting the RGB values obtained from the camera into HSV. Through this, the location of the algae is identified and when the amount of dissolved oxygen's decrease at the location is more than the reference value using the DO sensor, the algae removal device is driven to spray the algae removal solution. Raspberry Pi's camera uses OpenCV, and the motor movement is controlled according to the output value of the DO sensor and the result of the camera's green algae recognition. Algae recognition and spraying of algae removal solution were implemented through Arduino and Raspberry Pi, and the feasibility of the proposed portable algae removal device was verified through experiments.

• Proceedings of the KIEE Conference
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• 1998.11c
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• pp.764-766
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• 1998

An evaluation method for oxygen permeable characteristics of the membrane covering to each cathode of multiple cathode - single anode type dissolved oxygen sensor, which has high reproducibility and is capable of measuring multiple components in solutions. For this purpose, a measuring circuit for the multiple cathode type DO sensor was designed to lower the noise signal by adapting a digital LPF to readout the sensor output accurately. Digital LPF is designed by setting up the transfer function to set the cutoff frequency to 10Hz, and the transfer function is programmed by C language, and then the filtering characteristics are evaluated with the simulation and experiments. Using this LPF added measuring circuit for the multiple cathode type DO sensor, we have obtained the calibration factor for each cathode to calibrate the variation of the output signals. The calibration factor was obtained by measuring the sensor output signal followed by oxygen partial pressure, using the same oxygen permeable membrane at each cathode of the multiple cathode type DO sensor.

• Membrane Journal
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• v.14 no.2
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• pp.142-148
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• 2004

This paper presents the enhancement of oxygen transfer efficiency using vibrating intravascular lung assist device (VIVLAD) for patients having chronic respiratory problems. The flow rate was controlled by the pump and monitored by a built-in flow meter. The vibration apparatus was composed of a piezo-actuator, a function generator, and a power amplifier. Gas flow rates of up to 6 L/min through the 120-cm-long hollow fibers have been achieved by exciting a piezo-actuator. The output PVDF sensor and FRF (frequency response function) were investigated by various frequency in VIVLAD. As a result, the maximum oxygen transfer rate was found to occur with maximum amplitude and the transfer of vibration to the hollow fiber membranes. It was excited by the frequency band of 35 Hz at various distilled water flow rates, and various module types.

• Ocean and Polar Research
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• v.45 no.2
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• pp.33-42
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• 2023

Dissolved oxygen (DO) is a crucial parameter for assessing environmental conditions in aquatic ecosystems. However, commercial in situ dataloggers for oxygen optodes can be relatively expensive and limited in their specifications. In this paper, we present a novel design for a DO datalogger system based on the control boards family with RP2040 MCU chipset. Our design includes two types of dataloggers: a simple logging system and a programmable system for sampling rates via magnetic switches underwater for divers. We provide detailed descriptions of the system, including the MicroPython source code and drawings to aid in construction. We also discuss the various applications of our DO datalogger system in monitoring dissolved oxygen concentration in coastal waters and assessing the benthic metabolism of aquatic ecosystems. Our DO datalogger system provides an affordable and flexible option for researchers to accurately monitor DO concentrations in aquatic environments, and thereby improve our understanding of these complex ecosystems.

• KIPS Transactions on Computer and Communication Systems
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• v.12 no.5
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• pp.171-180
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• 2023

The three major sleep disorders in Korea are snoring, sleep apnea, and insomnia. Lack of sleep is the root of all diseases. Some of the most serious potential problems associated with sleep deprivation are cardiovascular problems, cognitive impairment, obesity, diabetes, colitis, prostate cancer, etc. To solve these problems, the Korean government provided low-cost national health insurance benefits for polysomnography tests in July 2018. However, insomnia patients still have problems getting treated in terms of time, space, and economic perspectives. Therefore, it would be better for insomnia patients to be allowed to test at home. The measuring device can measure six biosignals (eye movement, tossing and turning, body temperature, oxygen saturation, heart rate, and audio). A gyroscope sensor (MPU9250, InvenSense, USA) was used for eye movement, tossing, and turning. The input range of the sensor was in 258°/sec to 460°/sec, and the data range was in the input range. Body temperature, oxygen saturation range, and heart rate were measured by a sensor (MAX30102, Analog Devices, USA). The body temperature was measured in 30 ℃ to 45 ℃, and the oxygen saturation range was 0% for the unused state and 20 % to 90 % for the used state. The heart rate measurement range was in 40 bpm to 180 bpm. The measurement of audio signal was performed by an audio sensor (AMM2742-T-R, PUIaudio, USA). The was -42 dB ±1 dB frequency range was 20 Hz to 20 kHz. The measured data was successfully received in wireless network conditions. The system configuration was consisted of a PC and a mobile app for bio-signal measurement and data collection. The measured data was collected by mobile phones and desktops. The data collected can be used as preliminary data to determine the stage of sleep and perform the screening function for sleep induction and sleep disturbances. In the future, this convenient sleep measurement device could be beneficial for treating insomnia.

• Proceedings of the Korean Society for Agricultural Machinery Conference
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• 2017.04a
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• pp.60-60
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• 2017

화석연료의 고갈과 환경오염이 문제시 되면서 친환경 에너지개발에 대한 연구가 진행되고 있다. 그중 바이오디젤은 동,식물성유지 및 폐식용유를 이용하여 생산이 가능할뿐더러 농용엔진에 특별한 개조 없이 사용가능하다. 또한 바이오디젤 자체에 산소를 함유하고 있어 이산화탄소 저감에 효율적이다. 바이오 디젤에 관한 많은 연구가 수행되었으며, 기존의 연구는 단일유지의 폐식용유를 사용하여 바이오디젤을 생산하는 연구가 진행되었다. 하지만 가정에서 배출되는 식물성 폐식용유의 경우 여러 가지가 혼합되어 배출되고 있어, 혼합폐식용유지의 바이오디젤 특성평가가 필요하다. 따라서 본 연구에서는 폐식물성유지(폐대두유, 폐카놀라유, 폐해바라기유)를 중량비(1:4, 1:1.5 1:0.66, 1:0.25)로 혼합하여 바이오디젤을 생산하고, 생산한 바이오디젤을 농용기관에 이용하여 농용기관의 출력특성 및 배기배출물특성 평가를 실시하였다. 실험에 사용된 농용기관은 배기량이 673cc인 직접분사식 디젤기관(ND10DE, Daedong, Korea)이며, 엔진성능평가를 위해 토크는 토크센서(YDL-704s, Setech, Korea)를 사용하였다. 배기배출물 평가는 배기가스분석기(HG-550, Airlex, Germany)를 이용하여 이산화탄소, 질소산화물을의 배출량을 측정하였다. 폐식용유를 이용하여 생산한 바이오디젤과 경유의 기관성능을 비교한 결과 토크와 축출력의 경우 BD의 혼합량이 증가할수록 줄어들었다. 토크는 혼합된 유지에 따라 상용운전범위인 1500rpm~2400rpm에서 평균 대두와 카놀라유를 혼합하여 생산한 BD10은 7.2%, BD20은 12.1% 감소하였고, 대두와 해바라기유를 혼합하여 생산한 BD10은 11.3% BD20은 16.3% 감소하였다. 또한 해바라기와 카놀라유를 혼합하여 생산한 BD10은 8.3%, BD20은 14.6% 감소하였다. 이는 BD의 발열량이 경유에 비해 낮아 토크가 감소한 것으로 판단된다. 또한 배기배출물 평가의 경우 질소산화물은 BD의 함랑이 증가함에 따라 경유에 비해 배출량이 증가하는 경향을 보였고, 이산화탄소는 저감되는 것으로 나타났다. 이는 바이오디젤이 함산소연료이므로, 연료내의 산소로 인해 완전연소를 촉진시켜 이산화탄소를 저감시키고 질소산화물은 증가된 것으로 판단된다.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2003.05a
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• pp.514-517
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• 2003

Oxygen supply is one of the most basic things in human body. Breathing is controlled by the lungs' stationary function and the respiratory center which is in the mesulla oblongata. Nothing but, the external breathing that air movement between the lungs and atmosphere and the internal breathing that cellular air movement between the hemoglobin and a single cell. The adult's number of times of the respirations is about 15∼20 per 1 minute, but it depends ages, exercise, temperature, disease, etc. The important thing in detecting the respiration is that doing it in object person's resting time. Detecting the respiration have to be done without attracting any attention of object person. In present using method is detecting the pulse with catching an object person's wrist and observing the object person's movement. In this paper, we propose the mobile respiration detection diagnostic system using ultrasound sensing method that does not be influenced by the inertia error and the pressure error.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.02a
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• pp.475-475
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• 2013

Cuprous oxide ($Cu_2O$)는 밴드갭이 2.17 eV p-type 산화물 반도체로써 태양에너지 변환기, photocatalysis (광촉매작용), 센서, 스위칭 메모리 등 응용이 다양한 재료이다. 산화물 반도체의 기본 특성은 나노/마이크로 범위 안에서 재료의 표면형태, 크기, 구조와 형상 공간방향등에 크게 영향을 받는다. 그렇기 때문에 원하는 $Cu_2O$ 특성을 얻기 위해서 성장 거동을 아는 것은 매우 중요하다. RF 마그네트론 스퍼터법으로 rod 성장 사례는 잘 알려지지 않았다. 그래서 RF 마그네트론 스퍼터법 $Cu_2O$ rod 형성 실험을 통하여 $Cu_2O$ 형성과 성장 거동을 알아보았다. RF 마그네트론 스퍼터법으로 $Cu_2O$ rod를 glass 기판 위에 Cu metal target을 이용하여 형성시켰다. $Cu_2O$ rod 합성을 위해 기판온도 및 산소분압 O2/(Ar+O2)=3%, 5%, 7% 증착시간 등을 변화시켜 실험하였다. 성장된 rod의 분석은 XRD, SEM으로 확인하였다. 성장 거동은 증착온도와 증착시간에 차이를 보였다. 증착온도 $550^{\circ}C$에서 rod가 생성되는 것을 관찰하였다. 증착시간이 길어질수록 rod 길이가 길어지고 일정 시간이 지나면 rod의 길이 성장보다는 두께(폭)가 성장하는 것을 확인하였다. 증착온도 $550^{\circ}C$ 그리고 산소분압 3%, 5%, 7% 조건에서 rod 합성 실험을 하였을 때 3%, 5% 조건에서 rod의 성장을 확인하였다. 이때 3%, 5% 산소분압에 따라 rod의 모양이 변화하였다. 하지만 7% 조건에서는 rod가 성장하지 않았다. 이유는 3%, 5%에서는 Cu metal peak을 확인하였지만, 7% 조건에서는 Cu metal peak이 없었다. 이로부터 Cu metal이 $Cu_2O$ rod 생성에 영향을 미치는 중요한 요소임을 예상할 수 있었다.