• Proceedings of the Korean Information Science Society Conference
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• 2007.10b
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• pp.340-344
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• 2007

유비쿼터스 지능공간에서 사람의 행동과 위치를 모니터링하는 것은 서비스 제공을 위해 기본적이며 필수적인 단계이다. 본 논문에서는 스마트 펜던트(SmartPendant)의 카메라 영상과 GPS위치 정보를 이용한 새로운 웨어러블 컴퓨터를 제안한다. 우선, 행동 인식를 위해 영상간에 특정 픽셀 값 차와 옵티컬 플로우를 사용하였으며, 인식이 가능한 행동으로는 걷기, 멈춤, 방향전환이다. 또한, GPS를 이용한 사용자의 위치 정보는 위도와 경도에 대한 스트링값을 패킷값으로 변환하여 지능형 상황인지 서버에 전달된다.

• Korean Journal of Environment and Ecology
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• v.26 no.3
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• pp.463-471
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• 2012

Objective of this study is to provide basic information for developing more differentiated and targeted forest healing policy and Korean medical healing programs grounded on consumer preference for forest based Korean medical healing tourism products. The internet survey(CAWI) by percentage quota sampling with 400 Seoulite ages over 30 by the age, area, and gender was conducted, and 317 samples were used for a final analysis. 61.5% of the Seoulite associated 'forest bath/walking in the woods/tree' with an image of a forest based Korean medical healing tourism product, and preference for the product and the intention to use were positive at the percentages of 72.9% and 67.5%, respectively. Preferred areas were Seoul/Gyeonggi-do(53.5%) and Gangwon-do(38.8%). 'Stress solving and refreshment', 'taking a forest bath and a walk', and 'maintaining and promoting health' were the main purposes of the use. As for a therapy, 'walking therapy' was most preferred, and 'ergotherapy' was the next. First priority as for a use facility was 'healing trail', and 'professional medical facility' ranked second. Although important decision attributes were ' cost of use', 'food', and 'friendliness of medical staff', all the other sets of attributes related to use convenience, quality of medical service and tourism activities also recorded high, which forecasts higher consumer expectation for the product. As the result showing differences in consumer preference by the demographic segmentation, differentiated and segmented consumer needs should be considered when planing and managing a product. The scope of the study is limited to a demographic segmentation which is a basic stage of understanding consumer preference, therefore more detailed future researches on complicated and multi-dimensional consumer needs are required.

• Clinical and Experimental Pediatrics
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• v.46 no.2
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• pp.122-127
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• 2003

Purpose : Baby-walkers are used by many parents because of the convenience they provide in keeping children occupied, quiet, happy, and in stimulating ambulation. But, these devices have more risks than benefits. Therefore, we performed a study to evaluate the effects of baby-walkers on motor development of human infants according to the hours used in a day, total duration(months), and types of injuries associated with the walkers, and to establish effective methods. Methods : 1,045 questionnaires were filled out by parents who had a baby whose aged between 8 months and 15 months that visited local pediatric clinics and medical centers in Chonju and Iksan from May 1, 2002 to July 31, 2002. They were analyzed in a control group that didn't use babywalkers, a low-user group that used baby-walkers less than 2 hours a day and a high-user group that used them more than 2 hours a day. Results : The mean age of the 1,045 babies whose parents responded to the question investigation was $12.6{\pm}2.4$ months. The number of babies who used the baby-walkers were 811(77.6%). Crawling and walking alone were delayed in the high-user group. The parents who knew the side effects of the baby-walkers totalled 392(48.3%). Conclusion : The findings of this study revealed that many parents didn't know the effects of baby-walkers on motor development in their infants and the risks associated with baby-walkers. Therefore, we should educate parents on the risks of baby-walkers and recommend reducing the use of baby-walkers.

• Journal of agricultural medicine and community health
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• v.47 no.3
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• pp.166-180
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• 2022

Objective: This study evaluated the effects of a non-face-to-face obesity management program, implemented during the pandemic. Methods: The non-face-to-face obesity management program used the Intervention mapping protocol (IMP). The program was put into effect over the course of eight weeks, from September 14 to November 13, 2020 in 48 overweight and obese adults, who applied to participate through the Daegu Citizen Health Support Center. Results: IMP was first a needs assessment was conducted; second, goal setting for behavior change was established; third, evidence-based selection of arbitration method and performance strategy was performed; fourth, program design and validation; fifth, the program was run; and sixth, the results were evaluated. The average weight after participation in the program was reduced by 1.2kg, average WC decreased by 3cm, and average BMI decreased by 0.8kg/m² (p<0.05). The results of the health behavior survey showed a positive improvement in lifestyle factors, including average daily intake calories, fruit intake, and time spent in walking exercise before and after participation in the program. A statistically significant difference was seen (p<0.05). The satisfaction level for program process evaluation was high, at 4.57±0.63 point. Conclusion: The non-face-to-face obesity management program was useful for obesity management for adults in communities, as it enables individual counseling by experts and active participation through self-body measurement and recording without restriction by time and place. However, the program had some restrictions on participation that may relate to the age of the subject, such as skill and comfort in using a mobile app.

• Journal of the Korea Computer Graphics Society
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• v.27 no.3
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• pp.55-63
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• 2021

This study proposes an interface for providing mobile interaction suitable for mobile virtual reality (VR) and analyzes it through comparative experiments. The proposed interface is premised on not using additional equipment except for the mobile head-mounted display(HMD) in consideration of accessibility and usability. And the interface that controls the movement interaction using the user's gaze is designed in two phases. The key is to minimize the occurrence of negative factors such as VR sickness that can be caused by straight line movement in virtual reality. To this end, two phases are designed: an interface composed of forward/backward buttons to move the gaze toward the ground, and an interface composed of left and right buttons on the front in consideration of the gaze change in real walking motion. An application that can compare and analyze movement interactions through the proposed interface is produced, and a survey experiment is conducted to analyze the user's satisfaction with the interface experience and the negative impact on the movement process. It was confirmed that the proposed movement interaction reduced negative effects such as VR sickness along with a satisfactory interface experience for users.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.11a
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• pp.190-190
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• 2008

자연적으로 발생되는 파도, 비, 우박 등과 철도, 차량 및 엘리베이터 등과 같은 인위적인 설치, 이동에 의해 발생되는 진동에너지는 우리 일상생활에서 가장 흔하게 발생할 수 있는 에너지원인데, 이러한 진동에너지는 압전 소재를 이용하여 재생 가능하여 최근에는 이에 대한 연구가 활발히 진행되어 왔다. 예를 들면, 미국의 MIT에서는 인간이 걸을 때 신발에 가해지는 압력을 이용하여 전력을 발생시키는 연구를 진행하여 2.9 mW의 전력을 얻었다. 특히 이러한 기술은 인간의 걷기 운동 등과 같은 일상적인 동작으로 필요한 전력을 얻을 수 있고, 세라믹 소자를 이용하기 때문에 전자노이즈가 발생되지 않을 뿐 아니라 반영구적으로 사용할 수가 있어서, 소형 전자기기 등에 서 기존 이차전지를 대체 또는 보완 할 수 있는 기술로 검토되고 있다. PZT계 세라믹스는 높은 유전상수와 우수한 압전특성으로 이러한 압전발전 분야에서 가장 널리 사용되어지고 있다. 하지만 에너지 효율을 높이기 위하여 적층 구조의 제작 시 구조적 특성상 내부전극이 도포된 상태에서 동시 소결이 필요한데, $1000^{\circ}C$ 이상의 높은 소결온도 때문에 소재 원가가 낮은 Ag전극 대신 값비싼 Pd나 pt가 다량 함유된 Ag/Pd, Ag/Pt 전극이 사용되고 있어 경제성이 떨어지는 단점을 갖게 된다. 순수 Ag 전극을 사용하거나 Ag의 비율이 높은 내부전극을 사용하기 위해서는 $900^{\circ}C$ 이하에서 소결되고 우수한 전기적 특성을 보이는 압전 세라믹스 소재를 개발 하는 것이 필요하다. 따라서 본 연구에서는 압전특성이 우수한 $(Pb_{1-x}Cd_x)(Ni_{1/3}Nb_{2/3})_{0.25}(Zr_{0.35}/Ti_{0.4})O_3$ 계의 조성을 설계하고, 소결온도를 낮추기 위해서 2 단계 하소법을 이용하였다. 또한 $MnCO_3$, $SiO_2$, $Pb_3O_4$ 등을 소랑 첨가하여 액상 소걸 특성을 부여하여 소결 온도를 감소시키려는 시도도 하였다. 소결체의 전체적인 제조 공정은 일반적인 벌크 세라믹의 소걸 공정을 따랐다. 최종 소결된 시편을 XRD분석을 통하여 상을 확인하였고 SEM을 이용하여 미세조직을 관찰 하였다. 전기적 특성을 평가하기 위하여 두께를 1mm로 연마한 시편에 Ag 전극을 도포하여 $650^{\circ}C$ 에서 열처리한 후, 분극처리 하였다. Impedance analyzer를 이용하여 압전 특성 (전기기계결합계수 및 기계적품질계수)을 측정 하였고, 압전전하상수는 $d_{33}$-meter로 측정하였다. 본 연구에서는 압전체에 가해지는 하중의 크기, 시편의 크기, 하중을 가하는 방법, 에너지 저장회로의 최적화 등을 다양하게 시도하면서 에너지 변환 및 저장 효율을 평가하였다.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.06a
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• pp.306-306
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• 2008

기계적 에너지를 전기적 에너지로 변환하는 에너지 변환소자인 압전 세라믹스는 액추에이터, 변압기, 초음파모터, 초음파 소자 및 각종 센서로 응용되고 있으며, 그 응용분야는 크게 증가하고 있다. 최근에는 이러한 압전 소자를 앞으로 도래하는 ubiquitous, 무선 모바일 시대의 휴대용 전자제품, robotics, MEMS 분야 등의 대체 에너지원으로 응용하기 위한 연구가 진행되고 있다. 특히 인간의 걷기 운동 등과 같은 일상적인 동작으로 필요한 전력을 얻을 수 있고, 세라믹 소자를 이용하기 때문에 전자노이즈가 발생되지 않을 뿐 아니라 반영구적으로 사용할 수 가 있어서, 기존 이차전지를 대체 또는 보완 할 수 있는 방안도 검토되고 있다. PZT계 세라믹스는 높은 유전상수와 우수한 압전특성으로 전자세라믹스 분야에서 가장 널리 사용되어지고 있지만 $1200^{\circ}C$ 이상의 높은 소결온도 때문에 $1000^{\circ}C$ 부근에서 급격히 휘발되는 PbO로 인한 환경오염과 기본조성의 변화로 인한 압전 특성의 저하가 문제시 되고 있다. 또한 적층 세라믹스의 제작 시 구조적 특성상 내부전극이 도포된 상태에서 동시 소결이 필요한데, 융점이 낮은 Ag전극 대신 값비싼 Pd나 Pt가 다량 함유된 Ag/Pd, Ag/Pt 전극이 사용되고 있어 경제성이 떨어지는 단점을 갖게 된다. 순수 Ag 전극을 사용하거나 Ag의 비율이 높은 내부전극을 사용하기 위해서는 $900^{\circ}C$ 이하에서 소결되고 우수한 전기적 특성을 보이는 압전 세라믹스를 개발 하는 것이 필요하다. 따라서 본 연구에서는 압전특성이 우수한 $(Pb_{1-x}Cd_x)(Ni_{1/3}/Nb_{2/3})_{0.25}(Zr_{0.35}/Ti_{0.4})O_3$ 계의 조성을 설계하고, 소걸온도를 낮추기 위해서 2 단계 하소법을 이용하였다. 또한 $MnCO_3$, $SiO_2$, $Pb_3O_4$ 등을 소량 첨가하여 액상 소결 특성을 부여하여 소결 온도를 감소시키려는 시도도 하였다. 분말을 볼 밀링 (ball milling)을 통해 24시간 동안 혼합하고, 혼합된 분말은 $800^{\circ}C$에서 2시간 동안 하소하였다. 하소한 분말을 다시 72시간 동안 볼 밀링 하여 최종 분말을 얻었다. 최종 분말에 PVB를 첨가하여 직경 15mm의 디스크 형태로 성형한 후, 850~$975^{\circ}C$ 범위에서 온도를 변화시키면서 소결을 하였다. 최종 분말 및 소결된 시편을 XRD분석을 통하여 상을 확인하였고, SEM을 이용하여 미세조직을 관찰 하였다. 전기적 특성을 평가하기 위하여 두께를 1mm로 연마한 시편에 Ag 전극을 도포하여 $650^{\circ}C$에서 열처리한 후, 분극처리 하였다. 압전특성은 $d_{33}$-meter로 측정하였고, impedance analyzer를 이용하여 압전 특성 (전기기계결합계수 및 기계적품질계수)을 측정 하였다. 또한 강유전체 특성 평가 장치 (Precision-LC)를 이용하여 분극-전계 특성을 평가하였다. 이상의 연구를 통하여 소결 온도가 $900^{\circ}C$인 경우에서도 양호한 압전 특성을 확보 할 수 있었다.

• Journal of Internet of Things and Convergence
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• v.10 no.3
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• pp.57-64
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• 2024

In this paper, we propose a Line-of-Sight (LoS)/Non-Line-of-Sight (NLoS) identification- based Human Activity Recognition (HAR) system using Channel State Information (CSI) to improve the accuracy of HAR, which dynamically changes depending on the reception environment. to consider the reception environment of HAR system, the proposed system includes three operational phases: Preprocessing phase, Classification phase, and Activity recognition phase. In the preprocessing phase, amplitude is extracted from CSI raw data, and noise in the extracted amplitude is removed. In the Classification phase, the reception environment is categorized into LoS and NLoS. Then, based on the categorized reception environment, the HAR model is determined based on the result of the reception environment categorization. Finally, in the activity recognition phase, human actions are classified into sitting, walking, standing, and absent using the determined HAR model. To demonstrate the superiority of the proposed system, an experimental implementation was performed and the accuracy of the proposed system was compared with that of the existing HAR system. The results showed that the proposed system achieved 16.25% higher accuracy than the existing system.

• Childhood Kidney Diseases
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• v.4 no.1
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• pp.69-76
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• 2000

Purpose: The Pathogenesis of primary noctllrnal enuresis(PNE) is still controversial. Genetic factor and maturational delay of micturition reflex including arousal disorder, lack of nocturnal Arginine Vasopressin(AVP) release and functional bladder capacity have been suggested. We analyzed the risk factors of PNE. Methods: Fifty five children with PNE (20 enuretics diagnosed at school physical examination of the first grade students at Mok-Dong Elementary School and 35 enuretics (Age 6-7 year) diagnosed at Ewha Womans University Mok Dong Hospital) and 221 control students without PNE at school physical examination were included. Genetic, stress and developmental factors, arousability, water intake, urine volume, maximun voiding volume and daytime voiding dysfunction were compared. Results: 1) There was no significant difference between PNE and control group in sex ratio, birth order, percentage of working mothers, parental and child personality, age to start walking, school record and duration of sleep. 2) Family history in the PNE group was significantly higher than control group ($20.0\%\;vs\;2.7\%$)(P<0.05). 3) The difficulty in arousal in the PNE group was significantly more common than the control group ($70.9\%\;vs\;54.3\%$)(P<0.05). 4) Nocturnal water intake in the PNE group was significantly greater than the control group ($330{\pm}158.2\;mL\;vs\;235{\pm}129.5\;mL$). Nocturnal urine volume in the PNE group was significantly greater than the control group ( $390{\pm}61.5\;mL\;vs\;140{\pm}43.2\;mL$)(P<0.05). Daily water intake and daily urine volume did not significantly differ between the two groups. 5) Maximum urine volume per void in the PNE group was significantly lower than the control group ($107{\pm}35.9\;mL\;vs\;236{\pm}41.3\;mL$). Daytime voiding dysfunction in the PNE group was significantly more common than the control group ($80.0\%\;vs\;57.9\%$). The voiding frequency in the PNE group was significantly greater than the control group ($7.0{\pm}3.6\;vs\;5.4{\pm}1.6$)(P<0.05). Conclusion: In addition to genetic factors and maturational delay of micturition reflex (difficulty in arousal, nocturnal polyuria and decreased functional bladder capacity) nocturnal polydypsia was found to be the important risk factors fur PNE. So nocturnal fluid restriction should be encouraged as the first-line management of PNE.