• Proceedings of the Korean Vacuum Society Conference
• /
• 2014.02a
• /
• pp.471.2-471.2
• /
• 2014

We demonstrate here that an improvement in precursor film density (green density) leads to a great enhancement in the photovoltaic performance of CuInSe2 (CISe) thin film solar cells fabricated with Cu-In nanoparticle precursor films via chemical solution deposition. A cold-isostatic pressing (CIP) technique was applied to uniformly compress the precursor film over the entire surface (measuring 3~4 cm2) and was found to increase its relative density (particle packing density) by ca. 20%, which resulted in an appreciable improvement in the microstructural features of the sintered CISe film in terms of lower porosity, reduced grain boundaries, and a more uniform surface morphology. The low-bandgap (Eg=1.0 eV) CISe PV devices with the CIP-treated film exhibited greatly enhanced open-circuit voltage (VOC, from 0.265 V to 0.413 V) and fill factor (FF, from 0.34 to 0.55), as compared to the control devices. As a consequence, an almost 3-fold increase in the average power conversion efficiency, 3.0 to 8.2% (with the highest value of 9.02%), was realized without an anti-reflection coating. A diode analysis revealed that the enhanced VOC and FF were essentially attributed to the reduced reverse saturation current density (j0) and diode ideality factor (n). This is associated with the suppressed recombination, likely due to the reduction in recombination sites such as grain/air surfaces (pores), inter-granular interfaces, and defective CISe/CdS junctions in the CIP-treated device. From the temperature dependences of VOC, it was confirmed that the CIP-treated devices suffer less from interface recombination.

• Journal of the Korean institute of surface engineering
• /
• v.41 no.1
• /
• pp.1-5
• /
• 2008

In this work, improvement of mechanical and electrical properties of gate dielectric layer for flexible organic thin film transistor (OTFT) devices was investigated. In order to increase the mechanical flexibility of PVP (poly(4-vinyl phenol) organic gate dielectric, a very thin inorganic $HfO_2$ layers with the thickness of $5{\sim}20nm$ was inserted in between the spin-coated PVP layers. Insertion of the inorganic $HfO_2$ in the laminated organic/inorganic structure of PVP/$HfO_2$/PVP layer led to a dramatic reduction in the leakage current compared to the pure PVP layer. Under repetitive cyclic bending, the leakage current density of the laminated PVP/$HfO_2$/PVP layer with the thickness of 20-nm $HfO_2$ layer was not changed, while that of the single PVP layer was increased significantly. Mechanical flexibility tests of the OTFT devices by cyclic bending with 5 mm bending radius indicated that the leakage current of the laminated PVP/$HfO_2$(20 nm)/PVP gate dielectric in the device structure was also much smaller than that of the single PVP layer.

• The Journal of the Korea Contents Association
• /
• v.15 no.5
• /
• pp.592-606
• /
• 2015

Depression and mental illness across all age groups, and steady increasing in suicide rate are our major social problems which cause dramatically decreasing government competitiveness. While Korean government has implemented various policies to improve mental health and prevent suicide, it faces revealing issues in progress on implementation and referral management systems. The current research examined domestic and foreign cases to understand the actual status and directivity of ICT convergence plan in terms of mental health. The United States and the United Kingdom have provided convergent ICT service, telepsychiatric care to senior citizens in rural areas, children and adolescents, socially disadvantaged class, etc. In Korea, emergency-notice devices are installed to prevent suicide for single elderly people, and diverse mobile health devices are developing to cure depression and Alzheimer's disease. ICT convergent mental health care service is needed to save socioeconomic costs and realize universal welfare for an aging society. Social consensus on sharply conflict issues, medical law and medical devices about telepsychiatry service, effectiveness studies on users' unique psychiatric characteristics by life cycle, and region-specialized strategies for the least densely populated rural regions with lower access to medical care should be considered.

• Journal of the Korea Convergence Society
• /
• v.10 no.11
• /
• pp.275-282
• /
• 2019

Social Skills are one of the most important competency for student who live in the future Society. The purpose of this study is to propose a Forum Theatre Instruction utilizing smart devices as an alternative teaching and learning methods for enhancing the social skills of students, and to examine the effect of this instruction on the improvement of it. In order to achieve the purpose, the class was designed based on the 'Procedural Instructional Model for FTI using Digital Media', and the effectiveness of it was verified using 'SSIS'. FTI can be composed of six classes, and results of paired t-test showed that it was effective in enhancing students' social skills. Reflecting the interview results of the participant, the further requirements for improvement and efficient use of FTI were suggested.

• Journal of Biomedical Engineering Research
• /
• v.44 no.1
• /
• pp.41-52
• /
• 2023

With the international change in the medical device market owing to the development of innovative medical engineering and the use of various raw materials, a systematic and rational medical device classification system is needed to safely manage newly developed medical devices. This study aims to improve the domestic medical device classification system by proposing product establishment and segmentation. It is based on medical device products from the United States and Europe that are only available in foreign systems and are more subdivided than domestic products. This study analyzes and compares the domestic and foreign medical device classification systems by examining laws, guidelines, and analysis reports in Korea, the United States, and Europe. In accordance with product establishment and segmentation criteria, products subject to improvement are presented. This study contributes to safely managing medical devices that do not fit with the current classification system and to solving the confusion caused by the lack of international harmony in product classification systems.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.26 no.11
• /
• pp.1592-1598
• /
• 2022

This paper proposes an improvement system for the marginalized digital underprivileged of these services due to the lack of intuition and usability for the recently increasing number of unmanned ordering devices' interfaces and device environments. The problem with kiosk service is that it lacks intuition among design principles and cannot be used by wheelchair passengers in environments that meet general standing standards. To solve this problem, we propose a service that can use kiosk-like environments on mobile devices by photographing QR codes with mobile devices. As a result of the experiment, people in their 20s did not experience difficulties in using the existing kiosk model, but in the case of the elderly, it was difficult to use the kiosk, so they asked for help. The improved kiosk model was carried out in their 20s without difficulty, and the results showed that it was carried out without difficulty even in the case of the elderly.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
• /
• v.15 no.4
• /
• pp.257-270
• /
• 2022

In this paper, we design a smart factory risk improvement system and risk improvement method using AI edge devices. The smart factory risk improvement system collects, analyzes, prevents, and promptly responds to the worker's work performance process in the smart factory using AI edge devices, and can reduce the risk that may occur during work with improving the defect rate when workers perfom jobs. In particular, based on worker image information, worker biometric information, equipment operation information, and quality information of manufactured products, it is possible to set an abnormal risk condition, and it is possible to improve the risk so that the work is efficient and for the accurate performance. In addition, all data collected from cameras and IoT sensors inside the smart factory are processed by the AI edge device instead of all data being sent to the cloud, and only necessary data can be transmitted to the cloud, so the processing speed is fast and it has the advantage that security problems are low. Additionally, the use of AI edge devices has the advantage of reducing of data communication costs and the costs of data transmission bandwidth acquisition due to decrease of the amount of data transmission to the cloud.

• Journal of the Optical Society of Korea
• /
• v.18 no.4
• /
• pp.330-334
• /
• 2014

In this paper, we present an incoherent dual-parallel modulation linearized optical link employing two different optical wavelengths. Comparing with previous dual-parallel modulation, this linearization method prevents the recreation of distortion products and can be readily implemented. Furthermore, a dual-wavelength dual-parallel modulation linearized optical link constructed with the commercially available devices is experimentally demonstrated with a spurious-free dynamic range of $122.5dB.Hz^{4/5}$. More than 25 dB suppression of the intermodulation distortion, 15.6 dB improvement of spurious-free dynamic range and 1.5 dB improvement of compression dynamic range are achieved after linearization.

• Proceedings of the KIPE Conference
• /
• 2010.07a
• /
• pp.21-22
• /
• 2010

Matrix converter is direct power conversion system. Matrix converter has many merits that possible bidirectional power flow, input power factor own control and system without DC-link. But matrix converter has some demerits that need many switching devices and switching loss. This paper suggest optimal matrix converter control scheme for improvement for switching loss part. Proposed control scheme verified that 10% improvement in efficiency, input current's harmonic loss and output voltage's EMI improvement.

• Proceedings of the Korean Institute of Building Construction Conference
• /
• 2006.05a
• /
• pp.181-184
• /
• 2006

Recently, the balance of national properties of governmental offices and departments has been in deficit. Moreover, it has been also increasing rapidly. This study focuses on postal administration business which faces the financial crisis. The purpose of our study is to show devices for value improvement of pelt office. Research was based on a domestic post office which was decided to rebuild in Incheon Bupyeong. Research on domestic and foreign cases were carried out, superior cases for benchmarking was regulated so that these can be applied to the post offices to be built or to be remodeled.