Enhanced Overall Conversion Efficiency of Dye-Sensitized Solar Cells Using Nano-Hollow Patterns for Efficient Light Scattering

Moon, Sungjin,Ryu, Sang-Woo,Choi, Hak-Jong,Jun, Junho,Kim, Chaehyun,Lee, Hee-Chul,Lee, Heon American Scientific Publishers 2016 Journal of nanoscience and nanotechnology Vol.16 No.10

<P>Dye-sensitized solar cells (DSSCs) have attracted great attention due to their distinct efficiency, very low fabrication cost, good performance under diffuse light condition, and ability to be fabricated on flexible substrates. One of the main efficiency-limiting factors of DSSCs is the poor light absorption of dye molecules at longer wavelengths. In this work, we formed cylindrical nano-hollow patterns (CNHPs) between the TiO2 nanoparticle (TNP) film and the front transparent electrode by using the direct printing technique and etching process to improve the light absorption of dye molecules at longer wavelengths. In addition, optical properties such as diffused transmittance and light absorption were measured by using UV-visible spectrometer. Optical characterizations of the TNP films with CNHPs revealed strong light scattering within the wavelength range of similar to 600 similar to 800 nm Owing to the light scattering effect provided by the CNHPs formed in the TNP films, increases in the short-circuit photocurrent density and overall conversion efficiency of the DSSCs were observed.</P>

Bandwidth enlargement of low‐profile slot antenna using ground resonance mode

Moon, Sungjin,Kim, Hyeongdong John Wiley Sons, Inc. 2019 MICROWAVE AND OPTICAL TECHNOLOGY LETTERS Vol.61 No.2

<P><B>Abstract</B></P><P>In this paper, we propose a method to increase the coupling between the ground and the antenna to improve the radiation performance of the mobile antenna. By adjusting the length of the slot antenna located at the center of the 48 mm × 15 mm ground resonating at 2.45 GHz, the coupling between the ground and the antenna can be controlled. When the coupling between the ground and the antenna is sufficiently strong, the ground resonance mode is strongly excited and a better radiation performance can be obtained. As the length of the slot antenna increases from 5 to 10 mm, the coupling between the ground and the antenna becomes stronger and the impedance bandwidth of −10 dB at 2.45 GHz becomes five times wider from 160 MHz (6.5%) to 780 MHz (31.8%).</P>

Performance enhancement of ground radiation antenna by coupling with ground body

Moon, Sungjin,Jeon, Jihwan,Shin, Hyunwoong,Kim, Hyung Hoon,Kim, Hyeongdong John Wiley Sons, Inc. 2018 MICROWAVE AND OPTICAL TECHNOLOGY LETTERS Vol.60 No.12

<P><B>Abstract</B></P><P>In this paper, the effect of coupling between the antenna and ground characteristic mode is investigated by comparing the radiation performance of antennas located inside and outside the ground plane. In general, it is understood that an antenna occupying a larger space has better radiation performance. However, in this paper, it is shown that coupling between the antenna and ground is important for radiation performance, rather than the size occupied by the antenna. The antenna is strongly coupled with the ground characteristic mode when located inside the ground; the −10 dB bandwidth is 130 MHz at 2.45 GHz, and the measured realized efficiency is −0.64 dB in the 2.4‐2.5 GHz band. When the antenna protrudes from the ground plane, the coupling between the antenna and the ground characteristic mode is weak, achieving a narrower −10 dB bandwidth of 50 MHz at 2.45 GHz, and lower measured realized efficiency of −2.20 dB in the 2.4‐2.5 GHz band. In other words, the radiation performance of the same antenna is significantly influenced by the coupling with the ground.</P>

미분탄 연소과정의 수치모델링

문성진(Sungjin Moon),전상태(Sangtae Jeon),장범준(Beomjun Jang),김용모(Yongmo Kim) 대한기계학회 2011 대한기계학회 춘추학술대회 Vol.2011 No.6

The present study has numerically investigated the combustion processes of the pulverized coal. The pulverized coal combustion involves the complex physical processes such as devolatilization, char oxidation, turbulence-chemistry interaction, and radiative heat transfer. These physical processes are implemented in the framework of Eulerian-Lagrangian and Eulerian-Eulerian formulations. The pulverized coal combustion models developed in this study are validated against the experimental data of the pulverized coal jet flames. Numerical results indicate that the present approaches have the capability to realistically predict the essential features of pulverized coal combustion processes.

차량실내소음저감차량실내소음저감을 위한 제진재 위치 최적화 기법 개발

문성진(Sungjin Moon),김수곤(Sugon kim),박우선(Woosun Park) 한국자동차공학회 2010 한국자동차공학회 부문종합 학술대회 Vol.2010 No.5

In this study, an optimization method of damping sheet treatment was developed to reduce the structure-borne noise below 500 [Hz]. As a method to optimize the damping sheet treatment, both the velocity distribution and the sum of strain energy distribution on panels are investigated and used to determine where the damping sheet is patched. The optimization procedure was proposed to find the optimum damping treatment developed in this paper consists of panel contribution analysis, the velocity distribution and the sum of strain energy distribution on panels. As a result of this study, either not only both the design weight and the cost of damping material have reduced, but also the structure-borne noise has improved.

Performance analysis of packet errors on IEEE 802.11-based DCF and EDCF

Sungjin Shin,Jong-Moon Chung IET 2015 Electronics letters Vol.51 No.2

<P>The effect of packet size differences, that has not been taken into account in existing papers on the IEEE 802.11 distributed coordinated function (DCF) and 802.11e enhanced distributed coordinated function (EDCF), has been investigated, and improved throughput equations that lead to accurate performance representation in erroneous wireless channels are provided. Wi-Fi devices that use the DCF and the EDCF reduce the risk of data packet transmission failure using request to send (RTS) and clear to send (CTS) packets by removing the hidden node problem. However, as the bit error rate (BER) increases (especially near the signal coverage edge of the other communicating device), even though RTS/CTS packets may succeed in communication, data packets may fail due to packet errors based on their larger packet sizes. This phenomenon is confirmed through actual measurements and mathematical performance analysis is carried out to accurately express the performance of 802.11-based communications in erroneous conditions.</P>

Transportation Mode Detection for People with Mobility Disabilities: A Pilot Study on a User-independent Model

Sungjin Hwang,Jiwoong Heo,Jucheol Moon,Hansung Kim,Jaehyuk Cha,Kwanguk (Kenny) Kim 한국정보과학회 2021 한국정보과학회 학술발표논문집 Vol.2021 No.12

Period Independent Transportation Mode Detection for People with Mobility Disabilities: A Pilot Study with DenseNet

Sungjin Hwang,Jiwoong Heo,Jucheol Moon,Hansung Kim,Jaehyuk Cha,Kwanguk (Kenny) Kim 한국HCI학회 2022 한국HCI학회 학술대회 Vol.2022 No.2

Transportation mode detection (TMD) can help improving our daily life by understanding the mobility patterns of people. Such enhanced understanding of mobility can also be beneficial to people with mobility disabilities including wheelchair users. Moreover, as it is hard to collect large dataset from wheelchair users, it is important for TMD for wheelchair users (wTMD) to maintain similar performance on data from different period which might have dissimilar environmental or behavioral characteristics. However, we could not find studies evaluating such period independency of the wTMD model. Thus, we investigated wTMD performance on data from different period, and improved such performance by suggesting a new wTMD model. Our results showed that both our proposed model (DenseNet-based-model) and the baseline model (CNN-based-model) had period dependency, but our proposed model outperformed the baseline model when evaluated with data from different period. Our findings indicate the importance of the evaluation method and show that deep convolutional network with high information interchange can help improving wTMD performance on data from different period.

세계 모바일 통신 분야 연구의 의미망 분석을 통한 연구동향 분석

박성진(Sungjin Park),백승철(Seungcheol Baek),문혜정(Hyejung Moon) 한국경영학회 2017 한국경영학회 통합학술발표논문집 Vol.2017 No.08

이 연구는 곧 다가오는 5g 기술이 4차 산업혁명에 어떠한 영향을 미치는가에 대한 의문으로부터 시작한다. 미래를 마주하기 위해서는 과거의 데이터를 주의 깊게 볼 필요성이 있으므로 60년대부터 2017년 현재까지 세계 이동통신분야 선행연구를 토대로 빅 데이터 분석을 통한 동향분석 및 세대 별 기술을 중심으로 분석 하는 것이 목적이다. 이론적 배경에서 기술을 결합도와 상호연결성에 따라 구분한 GE 매트릭스를 바탕으로 세계 통신관련 연구를 분석하였다. 연구절차는 Atteveldt(2008)의 의미망분석 방법론을 준수하여, 의미망 분석하고 네트워크 분석으로 나온 기술들을 분석하였다. 기존의 논문들은 주로 차세대 기술에 대해 조사하고, 시나리오 분석과 기초 원리를 분석 또는 기술을 설명한 반면에, 본 연구는 과거의 통신 기술부터 현재 5g까지 총망라한 데이터를 수집하해 그 데이터를 전처리하고 빅데이터 분석을 하여 동향을 조사하는 연구를 한다. 1960년부터 2017년 6월 까지 ’mobile’ 키워드를 갖는 학제를 web of science의 약18만 여건의 연구 데이터를 대상으로 사용하였다. 전처리 과정을 거쳐 khcoder와 NodeXL를 사용해 동시출현성 분석, 연관성 분석, 연결성 분석 등을 수행하였다. 연구결과, 주된 연구 분야는 Network, Robot, Phone, Channel 네 가지 분야이다. Network분야의 주요 과제는 network, wireless, ad_hoc, mobility 등 이다. Robot 분야의 주된 과제는 control, vehicle, environment 등 이다. Phone 분야의 주요 연구는 cell, exposure, radiation 등 이다. Channel 분야의 주요 연구는 radio, performance, evaluation 등 이다. 이 결과 Network와 Health 분야에서 융합연구가 활발하게 수행된 것으로 확인되었으며, 다른 분야도 상대적으로 두 분야에 비해 상대적으로 낮을 뿐 90년대 이후로 활발하게 연구가 이루어져 있었다. 또한 56년간 장기간의 시계열 분석을 통해 신규로 대두되는 연구 분야를 탐색할 수 있고, 세대별 주요 이슈와 5G의 떠오르는 핵심 기술을 살펴 볼 수 있다. The study starts with questions about how the upcoming 5g technology will affect the Fourth Industrial Revolution. In order to face the future, it is necessary to pay close attention to past data. Therefore, it is aimed to analyze trends through big data analysis based on previous researches of world mobile communication from the 60’s to 2017, The theoretical background is based on the GE Matrix, which is based on the combination of technology and interconnectivity. The research procedure follows the Atteveldt (2008) semantic analysis methodology, analyzing the semantic network and analyzing the techniques of network analysis. While existing papers mainly investigate the next generation technologies, analyze the scenarios, analyze the basic principles, or describe the technology, this study collects data from the past communication technology to the current 5g, preprocesses the data, Do research to investigate trend by doing. From 1960 to June 2017, we used a database of about 180,000 web of sciences with the keyword ‘mobile’. Simultaneous appearance analysis, associativity analysis, and connectivity analysis were performed using khcoder and NodeXL after preprocessing. As a result of research, the main fields of research are Network, Robot, Phone, and Channel. The main challenges in the network are network, wireless, ad_hoc, and mobility. The main tasks in the robot field are control, vehicle, and environment. Major researches in the field of phone are cell, exposure, and radiation. Radio, performance, and evaluation are the main research areas in the channel field. As a result, it has been confirmed that the convergence researches are actively performed in the network and health fields, and the other fields are relatively low compared to the two fields and have been actively studied since the 1990s. In addition, through a 56-year long-term time-series analysis, we can explore new emerging research fields and look at major issues by generations and emerging key technologies of 5G.

비교란 Lysimeter를 활용한 논 토양에서의 살충제 Carbosulfan 용탈특성 구명

임성진 ( Sungjin Lim ),오영탁 ( Youngtak Oh ),김남희 ( Namhee Kim ),양지연 ( Jiyeon Yang ),최근형 ( Geunhyoung Choi ),류송희 ( Songhee Ryu ),문병철 ( Byeongchul Moon ),박병준 ( Byungjun Park ) 한국환경농학회 2016 한국환경농학회 학술대회집 Vol.2016 No.-

This study was conducted to investigate the leaching characteristics of insecticide carbosulfan using undisturbed lysimeter. Soil horizons of sandy loam, loam, and silty clay loam lysimeter were composed of 6, 6, and 5, and clay contents were ranged from 53.1-63.2, 40.2-47.7, and 32.6-39.2 %, respectively. Bulk densities of each lysimeter were 1.38, 1.30, and 1.35 Mg/m3, respectively. Carbosulfan was treated to each lysimeter at 14 days after rice planting, and water was supplied according to rice cultivation method. Pore volumes of sandy loam, loam, and silty clay loam lysimeter were calculated to 718.9, 764.2, and 735.9 L, and pore volume numbers of supplied water for rice cultivation were 2.1, 1.6, and 1.3, respectively. Movement of carbosulfan in each lysimeter was investigated through the residue of carbosulfan in 30, 55, 85, and 125 cm soil water from topsoil and leaching water. Liquid chromatography (LC)-mass spectrometry (MS)-MS was used for carbosulfan analysis in water sample. Recovery and limit of quantitation (LOQ) of carbosulfan in water were 101.1-106.4% and 50 ng/L. Changes of moisture tension, humidity, and temperature in sandy loam, loam, and silty clay loam lysimeter was not significantly different. Weight of silty clay loam lysimeter was higher than other lysimeter because of less leaching. Leaching volume decreased with increasing clay content of paddy soil, and the volume of sandy loam, loam, and silty clay loam lysimeter were 1964.7, 1868.4, and 1265.6 L, respectively. Total leaching content of carbosulfan (treatment content 1541 mg) during experiment period in sandy loam, loam, and silty clay loam lysimeter were 30.7, 19.4, 23.5 ng, respectively. The content in three lysimeter was not significantly different. However, carbosulfan in soil horizon of sandy loam, loam, and silty clay loam paddy soil were detected at 2222.1, 2146.0, and 166.3 ng, respectively. These results showed that the movement of carbosulfan in sandy loam, loam, and silty clay loam paddy soil was very low, and the movement in silt clay lam paddy soil was relatively lower than sandy loam and loam paddy soil.