Earticle

In this study, the explosion processes of the battery according to by heating was identified using complex sensors including temperature, infrared (IR), visible, and ultraviolet (UV) sensors. A safe chamber was prepared for the explosion of the batteries according to heating. In order to detect signals from the battery during heating, complex sensors including temperature, IR, visible, and UV sensors were used inside the safe chamber. The heating was increased from room temperature to 165℃ at 10℃/min and then, kept 165℃. During the heating was kept at 165℃, the battery was exploded and a temperature was increased up to 380℃ abruptly due to explosion of the battery. Before the battery was exploded, the signals of the sensors were not detected. However, during explosion of the battery, the signals of IR, visible, and UV sensors were strongly detected. By analyzing various signals of the these sensors, the explosion of the battery according to heating was investigated.

In this study, to check the function of managing the severity of ultraviolet rays with a smart watch, a popular health care IT device, It was tested whether measuring heart rate using a PPG(Photoplethysmography) sensor representatively used in a smart watch could tell skin changes caused by ultraviolet rays. Through this experiment, we examined the possibility that the skin color tanned by ultraviolet rays can be determined only by the heart rate measurement function of the PPG sensor. In addition, the possibility of expanding the heart rate measurement function of the PPG sensor to the use of skin condition management was considered. we used an Arduino-based reflective PPG sensor to measure changes in heart rate by selecting body sites with high and low UV rays exposure. A significant value was derived through tests considering factors such as gender, UV exposure, and age. As a result, the study identified the possibility of adding ultraviolet rays and skincare items to future smart watch healthcare items and the possibility of expanding skin measurement methods. It is also possible to suggest the direction of future research.

In this article, a UV sensor that is an appropriate tool for fire detection has been designed and constructed. The structure of this UV sensor is an air-filled single-wire detector that is able to operate under normal air condition. A reflective CsI photocathode is installed at the end of the sensor chamber to generate photoelectrons in the ion chamber. An electric current is produced by accelerating photoelectrons to the anode in the electric field. The detector is able to measure the intensity of the incident UV rays whenever the current is sufficiently high. Therefore, the sensitivity coefficient of this sensor is found to be $7.67{\times}10^{-6}V/photons/sec$.

An ultraviolet (UV) image sensor is an extremely important optoelectronic device used in scientific and medical applications because it can detect images that cannot be obtained using visible or infrared image sensors. Because photodetectors and transistors are based on different materials, conventional UV imaging devices, which have a hybrid-type structure, require additional complex processes such as a backside etching of a GaN epi-wafer and a wafer-to-wafer bonding for the fabrication of the image sensors. In this study, we developed a monolithic GaN UV passive pixel sensor (PPS) by integrating a GaN-based Schottky-barrier type transistor and a GaN UV photodetector on a wafer. Both individual devices show good electrical and photoresponse characteristics, and the fabricated UV PPS was successfully operated under UV irradiation conditions with a high on/off extinction ratio of as high as $10^3$. This integration technique of a single pixel sensor will be a breakthrough for the development of GaN-based optoelectronic integrated circuits.

Ultraviolet (UV) photodetectors are used in various industries and fields of research, including optical communication, flame sensing, missile plume detection, astronomical studies, biological sensors, and environmental research. However, general UV detectors that employ Schottky junction diodes and p-n junctions have high fabrication cost and low quantum efficiency. In this study, we investigated the characteristics of materials used to manufacture UV photodetectors in a low-cost solution process that requires easy fabrication of flexible substrates. We fabricated p-type NiO and n-type ZnO substrates with wide band gap by the sol-gel method and compared the characteristics of substrates prepared under different spin-coating and heat-treatment conditions.

This paper proposes a new type of ultraviolet (UV) sensor coated with Azobenzene polymer material, a functional polymer that has recently been gaining interest in strain gauge equipment. Azovenzene polymers react reversively to ultraviolet rays, transforming the internal structure of the material. It is a technology that measures the change in strain induced by the ultraviolet light to the Azobenzene polymer using an electric strain gauge and detects ultraviolet rays from it. In particular, sensors are designed to determine the direction in which UV rays are introduced.

본 논문은 자외선 광학센서 개발에 관한 것이다. 기존에 반도체 기반 자외선 센서를 대체하기 위해 개발된 단주기 광섬유격자기반 자외선 센서에 대한 측정 민감도를 향상시키기 위한 다양한 장치들을 설계하고 실험을 통해 성능을 확인하였다. 최근 연구를 통해 자외선 흡수에 따라 인장력이 유도되는 아조벤젠 폴리머 재료와 장력에 따른 광섬유격자 특성 변화를 조합하여 새로운 자외선 센서의 개념이 제시되었다. 본 연구에서는 광섬유격자 기반 자외선 센서에서 흡수하지 못하고 통과되는 자외선 잔광을 반사판을 이용해서 다시 반사시켜 센서에서 재흡수되는 원리로 센서의 민감도를 향상시켰다. 본 논문에서는 반사판의 종류를 선정하고 반사판의 곡률반경을 최적화하였다. 또한 기존의 원통형 집광렌즈를 이용한 민감도 향상 기술을 접목 시켜 아무런 장치가 없을 때와 비교해서 약 15배의 성능을 향상시키는 결과를 얻었다. 또한 외부 환경 효과를 줄이기 위한 패키지 모듈을 제작하여 적용하고 그 특성을 분석하였다.

This study was focused on developing an optical sensor that monitors ultraviolet (UV) light. Recently, we proposed and demonstrated a novel, highly sensitive UV sensor based on a fiber Bragg grating (FBG). To ensure that the incident UV light is focused on the FBG surface, the sensor was coated with an azobenzene polymer material that acts as a UV-induced stretchable functional material, in combination with a cylindrical focal lens. In this study we have improved the sensitivity of the sensor by employing a cylindrical focal mirror as a curved reflector, to refocus the UV light passing through the FBG. We considered the performance of several different types of reflectors and chose the optimal radius of curvature for the reflector. Compared to the UV sensor without an auxiliary device, the sensitivity of the FBG sensor with a focal lens and a curved reflector was 15 times as high.

본 연구에서는 우주 방사선 환경을 고려하여 SiC PIN 구조 기반 자가발전형 자외선(UV) 센서의 광응답 특성과 전극 구조의 영향을 분석하였다. 가장자리(edge-type) 및 격자(mesh-type) 전극 구조를 적용한 소자를 제작하고, 양성자 조사 전후의 자외선 및 백색광 응답을 비교하였다. 자외선 조사 시 두 구조 모두 0 V에서 광전류가 발생해 자가발전 동작을 확인했다. 양성자 조사 후 edge-type은 광전류가 크게 감소한 반면, mesh-type은 상대적으로 안정적인 응답을 유지했다. 백색광 조건에서도 양성자 조사 후 두 구조 모두 광전류가 감소하였으며, 0 V 기준 광전류 감소폭은 mesh-type이 edge-type보다 작게 나타났다. 결론적으로 SiC PIN 소자의 자가발전형 UV 센서 활용 가능성을 확인하였으며, 방사선 환경에서는 mesh-type 전극이 응답 안정성 확보에 유리한 설계임을 제시한다.

In this study, we researched the photoresponse of self-powered UV sensors using SiC PIN structures for space radiation environments. We also analyzed the effect of electrode structures. We made devices with edge-type and mesh-type electrodes, and we compared their response to UV and white-light before and after proton irradiation. Under UV light, both structures generated photocurrent at 0 V. This confirms the self-powered operation. After proton irradiation, the photocurrent of the edge-type structure decreased a lot. However, the mesh-type structure showed a relatively stable response. Under white-light, the photocurrent of both structures also decreased after proton irradiation, but the difference between the two electrode types became even larger. The mesh-type structure showed much better performance than the edge-type. As a result, this study shows that SiC PIN devices can be used as self-powered UV sensors. Also, we suggest that the mesh-type electrode is a better design for UV response stability in radiation environments.

본 연구의 목적은 자외선 사진 콘텐츠의 융합적 활 용을 위하여 디지털카메라 이미지센서의 표면 가공방 법을 제시하고자 하는 것이다. 따라서 본 논문은 표면가공 시 센서에 적용되는 물 리적 요소들을 수치화하여 구체적이고, 재현이 가능한 이미지센서 표면가공 방법을 찾고자 하였으며, 자외선 대역에 대한 반응 유무 확인 및 히스토그램의 변화를 통하여 표면가공 과정 전, 후의 결과 차이를 비교, 분석을 시도하였다. 연구결과 및 내용은 다음과 같다. 첫째, 자외선 차단체를 활용하여 가공 전, 후 이미 지센서의 반사 자외선 반응 유무를 확인하였다. 둘째, 히스토그램 상의 자외선 영역의 증가를 통하 여 가공 후 센서의 자외선 대역에 대한 반응 변화를 확인할 수 있었다. 이러한 본 연구의 결과는 디지털카메라 이미지센서 의 표면가공을 통하여 보다 효율적인 자외선 이미지 취득의 가능성을 확인하였으며, 해당 연구를 기반으로 후속 연구에서는 보다 고사양의 센서에 동일한 표면 가공 과정을 적용하여 고화질의 자외선 이미지 취득 이 가능할 것으로 기대된다.

The purpose of this study is to present a surface processing method for digital camera image sensors for convergent utilization of ultraviolet photographic contents. Therefore, this paper sought to find a concrete, reproducible image sensor surface processing method by quantifying the physical elements applied to sensors during surface processing, and attempted to compare and analyze the differences in results before and after surface processing through changes in the response and histogram. The results and contents of the study are as follows: First, we used sunscreen to check the presence of reflected ultraviolet reactions of image sensors before and after processing. Second, the increase in ultraviolet region on the histogram allowed us to see the changes in the response to the ultraviolet band of the sensor after processing. The results of this study confirmed the possibility of more efficient ultraviolet image acquisition through surface processing of digital camera image sensors, and based on this study, it is expected that high-definition ultraviolet image acquisition will be possible by applying the same surface process to higher-quality sensors.