• 인간식물환경학회지
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• 제22권3호
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• pp.255-268
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• 2019

Horticultural therapy, as a kind of complementary alternative therapies using nature as a medium, is an intervention method that can be applied to various subjects by utilizing horticultural activities that anyone can enjoy as a leisure activity. This research defined the resilience of individuals as a personal characteristic, and examined differences in the intervention effect of horticultural activities depending on the level of resilience. The results obtained in this study can be utilized in planning a horticultural activity program and setting the purpose and goals of horticultural activity programs. The subjects of this study were divided into the high resilience experimental group (Group A), the low resilience experimental Group (Group C), the high resilience control group (Group B), and the low resilience control group (Group D). The experiment was conducted in the campus of G University from September to November 2017, and the experimental group participated in the program once per week, a total of 10 sessions. The Korean version of the Connor-Davidson Resilience Scale, autonomic nervous assessment, and the interpersonal relationship change scale were carried out as pre- and post-assessment. Statistical analysis was performed using a non-parametric test. Group A showed statistically significant positive changes in relaxation of physical tension and stability. In conclusion, those with high resilience showed the higher intervention effects of horticultural activities on physical relaxation and stability than those with low resilience. However, there were some possible limitations in this study. Since the number of subjects was small and subjects were limited to college students, it is impossible to generalize the results of this study. Therefore, it is necessary to conduct follow-up studies to address and overcome these limitations.

• 한국산학기술학회논문지
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• 제20권2호
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• pp.649-654
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• 2019

가상 환경과의 안정적인 상호작용은 사용자의 안전을 위해서 뿐만 아니라 사용자의 몰입감 향상을 위해서도 반드시 필요하다. 특히 현실감 높은 가상 강체 모델을 구현하기 위해서는 가상 강체 모델인 가상 스프링 상수를 가능한 크게 설계해야 한다. 그러나 가상 스프링 상수를 크게 하면 시스템이 불안정해지므로, 가상 스프링 상수의 크기에는 제한이 있다. 단일샘플링 주기를 이용하는 기존 방법보다 가상 스프링의 안정성 영역을 크게 하기 위해서 제안된 방법이 고주파 영차홀드를 포함한 햅틱 시스템 모델이다. 본 논문에서는 고주파 영차홀드의 샘플링 주기, 햅틱 장치의 물리적 댐퍼 크기와 안정적인 가상 스프링 최댓값과의 관계를 시뮬레이션을 통해 분석한다. 물리적 댐퍼 크기가 커질수록, 고주파 영차홀드의 샘플링 주기가 짧아질수록 가상 스프링의 안정성 영역은 커진다. 그리고 제시된 방법에서 비율 N이 40보다 커지면 물리적 댐퍼크기에 따라 안정성 영역을 기존 방법보다 약 3배~8배 더 크게 만들 수 있다. 따라서 본 방법이 가상환경 속 사용자의 현실감 향상에 도움이 될 것이다.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2014년도 제46회 동계 정기학술대회 초록집
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• pp.490.1-490.1
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• 2014

The ZnO nanowire (NW)-based nanogenerators (NGs) can have rectifying current and potential generated by the coupled piezoelectric and semiconducting properties of ZnO by variety of external stimulation such as pushing, bending and stretching. So, ZnO NGs needed to enhance durability for stable properties of NGs. The durability of the metal electrodes used in the typical ZnO nanogenerators(NGs) is unstable for both electrical and mechanical stability. Indium tin oxide (ITO) is used as transparent flexible electrode but because of high cost and limited supply of indium, the fragility and lack of flexibility of ITO layers, alternatives are being sought. It is expected that carbon nanotube and Ag nanowire conductive coatings could be a prospective replacement. In this work, we demonstrated transparent flexible ZnO NGs by using CNT/Ag nanowire hybrid electrode, in which electrical and mechanical stability of top electrode has been improved. We grew vertical type ZnO NW by hydrothermal method and ZnO NW was coated with hybrid silicone coating solution as capping layer to enhance adhesion and durability of ZNW. We coated the CNT/Ag nanowire hybrid electrode by using bar coating system on a capping layer. Power generation of the ZnO NG is measured by using a picoammeter, a oscilloscope and confirmed surface condition with FE-SEM. As a results, the NGs using the CNT/Ag NW hybrid electrode show 75% transparency at wavelength 550 nm and small change of the resistance of the electrode after bending test. It will be discussed the effect of the improved flexibility of top electrode on power generation enhancement of ZnO NGs.

• KSBB Journal
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• 제20권5호
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• pp.387-391
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• 2005

고온성 및 초고온성 세균과 고세균 13종 모두에서 관찰되는 167종류 총 16,299개의 보존적 유전자들에 대한 분석을 수행하였다. 단백질대사 관련 유전자들이 80개로 전체 보존적 유전자의 $47.9\%$였으며, 중온성 세균을 제외하고 고온성과 초고온성 세균들에서만 관찰되는 공통유전자는 없어 열 안정성은 특정 단백질의 유무에 따라 이루어지지 않는 것을 알 수 있었다. 하지만 초고온성 세균들은 reverse gyrase를 공통적으로 가지고 있어 고온에서의 DNA의 열안전성에 중요한 역할을 하는 것으로 생각되었다. 유전자보유 계통수와 165 rRNA 유전자 계통수의 비교결과 초고온성 진정세균과 고온성 고세균인 Methanobacterium thermoautotrophicum의 분포 양상이 서로 다르게 나타났다. 167개의 공통 유전자가 한 유전체에서 보이는 distance value들의 평균과 분산에서는 초고온성 진정세균, 초고온성 고세균, 고온성 고세균들끼리 유사한 값을 갖는 것으로 나타났다.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2008년도 춘계학술대회논문집
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• pp.442-448
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• 2008

This paper presents an approach to define an optimal piezoactuator length to actively control structural vibration. The optimal ratio of the piezoactuator length against beam length when a pair of piezoceramic actuator and accelerometer is used to suppress unwanted vibration with direct velocity feedback (DVFB) control strategy is not clearly defined so far. It is well known that direct velocity feedback (DVFB) control can be very useful when a pair of sensor and actuator is collocated on structures with a high gain and excellent stability. It is considered that three different collocated pairs of piezoelectric actuators (20, 50 and 100 mm) and accelerometers installed on three identical clamped-clamped beams (300 * 20 * 1 mm). The response of each sensor-actuator pair requires strictly positive real (SPR) property to apply a high feedback gain. However the length of the piezoactuator affects SPR property of the sensor-actuator response. Intensive simulation and experiment shows the effect of the actuator length variation is strongly related with the frequency range of SPR property. A shorter actuator gave a wider SPR frequency range as a longer one had a narrower range. The shorter actuator showed limited control performance in spite of a higher gain was applied because the actuation force was relatively small. Thus an optimal length ratio (actuator length/beam length) was suggested to obtain relevant performance with good stability with DVFB strategy. The result of this investigation could give important information in the design of active control system to suppress unwanted vibration of smart structures with piezoelectric actuators and accelerometers.

• 한국인터넷방송통신학회논문지
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• 제17권2호
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• pp.39-44
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• 2017

본 연구에서는 국내 콘텐츠 생산 및 유통방식의 급격한 변화에 따른 방송장비 구매 수요처의 절대적인 장비구매 인식을 비교하였으며 이에 수요자가 지각하는 국산 방송장비의 기술 신뢰도, 시스템 안정성 등의 정보의 정도가 장비구매에 미치는 영향을 연구모델을 통해 분석하였다. 방송 장비 수요에 관한, 기존 연구 데이터의 미진함으로 인하여 방송장비 전문가들과의 심층인터뷰와 설문조사를 병행하였다. 분석 결과로 외산장비에 비해 국내 장비의 단품구매와 시스템, Block구매의 경우가 많아 호환 경쟁력이 미흡하고 기술발전이 늦다. 국내 방송장비수요처가 인식하고 있는 국산방송 장비에 대한 선호, 만족도의 향상을 기하기 위한 기술 신뢰도 증진과 핵심 주요장비의 개발이 시급하며 소출력 송신기 안테나, 모니터장비에 국한되어있는 국산 장비의 공급을 확장하기 위한 개발이 시급하고 해외진출과 시장을 확보하기 위한 국내육성 지원도 요구된다.

• Geomechanics and Engineering
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• 제31권1호
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• pp.15-30
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• 2022

Slope stability during the excavation of twin road tunnels is considered crucial in terms of safety. In this research, physical model testing and numerical analysis were used to investigate the characteristics of the settlement (uz) and vertical stresses (σz) along the two tunnel sections. First, two model tests for a (fill-rock) slope were conducted to study the settlement and stresses in presence and absence of slope support (plate support system). The law and value of the result were then validated by using a numerical model (FEM) based on the physical model. In addition, a finite element model with a slope supported by piles (equivalent to the plate) was used for comparison purposes. In the physical model, several rows of plates have been added to demonstrate the capacity of these plates to sustain the slope by comparing excavating twin tunnels in supported and unsupported slope, the results show that this support was effective in the upper part of the slope, while in the middle and lower part the support was limited. Additionally, the plates appear to induce less settlement in several areas of the slope with differing settlement and stress distribution as compared to piles. Furthermore, as a results of the previous mentioned investigation, there are many factors influence the stress and settlement distribution, such as the slope's cover depth, movement during excavation, buried structures such as the tunnel lining, plates or piles, and the interaction between all of these components.

• Archives of Plastic Surgery
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• 제38권6호
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• pp.821-828
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• 2011

Purpose: The authors applied Bilhaut-Cloquet procedure to Wassel type III and IV duplicated thumb, which was limited to patients with Wassel type I, II. This procedure was applied in order to improve the growth potential, range of joint motion, joint stability and cosmetic outcome. Methods: Sixteen patients received Bilhaut-Cloquet procedures to correct duplicated thumbs from May, 2005 to December, 2010. Seven patients were Wassel type III, nine patients were type IV. This procedure was applied not only to balanced type, but also unbalanced type or convergent type. Five patients were balanced type and eleven patients were unbalanced type. Convergent type of Wassel type IV was three. Sex ratio was the same, mean age at the operation was 20.1 months old (8~52 months old). Angular deformity, joint stability and range of joint motion and cosmetic outcome were considered together and estimated in Tada score. Also, postoperative subjective satisfaction score of the parents was evaluated by a 100-points scale. Results: Mean subjective satisfaction scored 75 points at 28 months after the operation. Radiologic study showed bony union of proximal phalangeal bone and stable joint in all patients. Range of motion was mean 20 degrees in interphalangeal joint and mean 73 degrees in metacarpophalangeal joint. Tada score showed 'good' in eleven patients (68.8%), 'fair' in three patients (18.7%) and 'poor' in two patients (12.5%). In seven patients those who were able to follow up for a long term showed no significant difference in length of proximal and distal phalangeal bones compared to the opposite thumb. Conclusion: Bilhaut-Cloquet procedure can be applied not only to balanced type of Wassel type III, IV duplicated thumb, but also to unbalanced type or convergent type that focused on functional reconstruction and cosmetic improvement.

• 한국지반공학회논문집
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• 제38권7호
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• pp.39-47
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• 2022

본 연구는 도심지 내에 위치한 학교와 아파트 등 지반구조물들의 재해 위험성을 검증하기 위해 비탈면붕괴에 대한 안정성 평가를 수행하고자 한다. 이에 광주광역시에 위치한 𐩒𐩒고등학교 뒤편의 비탈면이 2018년 8월에 집중호우로 인하여 붕괴되었다. 일반적으로 장마철이면 비탈면 주위로 배수가 원활하게 진행되겠지만, 붕괴 시 비탈면 표층에서 침투수의 다량 용출과 지표면을 따라 포화된 지층을 따라 얕은파괴가 진행되었다. 붕괴 원인을 분석하기 위해 직접 확인하지 못하는 비탈면 상부지역을 무인항공기를 이용하여 영상촬영을 하였다. 영상분석을 통해 경사도를 이용한 수치표고모형(DEM)을 수행하였고, 강우 흐름 방향, 벌목지역의 넓이와 폭, 길이를 계산할 수 있었다. 10일 동안 지속된 강우로 인한 붕괴사면의 시간별 불안정성에 대한 변화를 수치해석을 통하여 분석하였다.

• 청정기술
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• 제28권2호
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• pp.97-102
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• 2022

Lithium sulfur (Li-S) batteries have attracted considerable attention as a promising candidate for next-generation power sources due to their high theoretical energy density, low cost, and eco-friendliness. However, the poor electrical conductivity of sulfur and its insoluble discharging products (Li₂S₂/Li₂S), large volume changes, severe self-discharge, and dissolution of lithium polysulfide intermediates result in rapid capacity fading, low Coulombic efficiency, and safety risks, hindering Li-S battery commercial development. In this study, a three-dimensionally (3D) connected hierarchical porous carbon framework (HPCF) derived from waste sunflower seed shells was synthesized as a sulfur host for Li-S batteries via a chemical activation method. The natural 3D connected structure of the HPCF, originating from the raw material, can effectively enhance the conductivity and accessibility of the electrolyte, accelerating the Li⁺/electron transfer. Additionally, the generated micropores of the HPCF, originated from the chemical activation process, can prevent polysulfide dissolution due to the limited space, thereby improving the electrochemical performance and cycling stability. The HPCF/S cell shows a superior capacity retention of 540 mA h g^-1 after 70 cycles at 0.1 C, and an excellent cycling stability at 2 C for 700 cycles. This study provides a potential biomass-derived material for low-cost long-life Li-S batteries.