Impact of Incorporating Nitrogen Atoms in Naphthalenediimide-Based Polymer Acceptors on the Charge Generation, Device Performance, and Stability of All-Polymer Solar Cells

Kim, Sang Woo,Wang, Yang,You, Hoseon,Lee, Wonho,Michinobu, Tsuyoshi,Kim, Bumjoon J. American Chemical Society 2019 ACS APPLIED MATERIALS & INTERFACES Vol.11 No.39

<P>Substitution of C atoms in a polymer backbone by N atoms allows for the facile tuning of the energy levels as well as the backbone conformation and packing structures of conjugated polymers. Herein, we report a series of three polymer acceptors (<I>P</I><SUB>A</SUB>s) with N atoms introduced at different positions of the backbone and investigate how these N atoms affect the device performances of all-polymer solar cells (all-PSCs). The three <I>P</I><SUB>A</SUB>s, namely, P(NDI2DT-BTT), P(NDI2DT-PTT), and P(NDI2DT-BTTz), are composed of naphthalenediimide (NDI)-based and benzothiadiazole (BT)-based derivatives (dithiophene-BT (BTT), dithiophene-thiadiazolepyridine (PTT), and dithiazole-BT (BTTz)). The PTT and BTTz units are synthesized by replacing the C atoms in BT and thiophene, respectively, with N atoms, which effectively tune the optical, electrochemical, and charge-transporting properties of the corresponding <I>P</I><SUB>A</SUB>s. The all-PSCs using poly[(2,6-(4,8-bis(5-(2-ethylhexyl)thiophen-2-yl))benzo[1,2-<I>b</I>:4,5-<I>b</I>′]dithiophene)-<I>co</I>-(1,3-di(5-thiophene-2-yl)-5,7-bis(2-ethylhexyl)benzo[1,2-<I>c</I>:4,5-<I>c</I>′]dithiophene-4,8-dione)] (PBDB-T) as a polymer donor and P(NDI2DT-PTT) as <I>P</I><SUB>A</SUB> exhibit a significantly enhanced power conversion efficiency (PCE) of 6.95%, whereas the all-PSCs based on the other <I>P</I><SUB>A</SUB>s show relatively lower PCEs (6.02% for PBDB-T:P(NDI2DT-BTT) and 1.43% for PBDB-T:P(NDI2DT-BTTz)). The high PCE of the PBDB-T:P(NDI2DT-PTT) device is due to the superior charge transfer and charge dissociation, resulting from the closely matched energy levels between PBDB-T and P(NDI2DT-PTT), as well as a more favorable bulk heterojunction morphology with improved miscibility. Importantly, the P(NDI2DT-PTT)-based all-PSC device shows improved air stability compared to the P(NDI2DT-BTT)-based device, which is most likely due to a decreased lowest unoccupied molecular orbital level of the <I>P</I><SUB>A</SUB>. Our findings suggest that the incorporation of N atoms into the <I>P</I><SUB>A</SUB>s is an effective strategy for improving the efficiency and stability of all-PSCs.</P> [FIG OMISSION]</BR>

평판형 히터를 이용한 알루미늄과 타이타늄 산화물 나노유체의 풀비등 임계열유속에 관한 실험적 연구

안호선(HoSeon Ahn),김형대(Hyung Dae Kim),조항진(Hangjin Jo),강순호(Soonho Kang),김무환(Moo Hwan Kim) 대한기계학회 2009 大韓機械學會論文集B Vol.33 No.10

Pool boiling heat transfer and critical heat flux (CHF) of water-based nanofluids with alumina and titania nanoparticles of 0.01% by volume were investigated on a disk heater at saturated and atmospheric conditions. The experimental results showed that the boiling in nanofluids caused the considerable increase in CHF on the flat surface heater. It was revealed by visualization of the heater surface subsequent to the boiling experiments that a major amount of nanoparticles deposited on the surface during the boiling process. Pool boiling of pure water on the surface modified by such nanoparticle deposition resulted in the same CHF increases as what boiling nanofluids, thus suggesting the CHF enhancement in nanofluids was an effect of the surface modification through the nanoparticle deposition during nanofluid boiling. Possible reasons for CHF enhancement in pool boiling of nanofluids are discussed with surface property changes caused by the nanoparticle deposition.

Effect of Supply and Return Locations of a Floor - Supply Cooling System on Thermal Comfort

Youngil Kim,Hoseon Yoo,Joseph Kim 대한설비공학회 2001 International Journal Of Air-Conditioning and Refr Vol.9 No.4

This study numerically investigates thermal comfort of a space cooled by a floor-supply air-conditioning system, in which three different combinations of supply and return locations, one floor-supply/ceiling-return and two floor-supply/floor-return, are treated. A complementary experiment is performed to validate the present numerical analysis, and the prediction agrees favorably with the measured data. In the numerical procedure, a simplified model mimicking the inlet flow through a diffuser is developed for efficient simulations. The calculated results show that the ceiling-return type is far better in terms of thermal comfort than the floor-return ones within the extent of this study, which seems to be caused by effective vertical penetration of the supply air against natural convection. It is also revealed that the arrangement of port locations in the floor-supply/floor-return system has insignificant effect on the cooling performance. For selecting a proper system, other characteristics including the heating performance should be accounted for simultaneously with the present considerations.

이동 컴퓨팅 환경을 위한 2단계 캐쉬 관리 기법

김호선(HoSeon Kim),황종선(Chong-Sun Hwang),이종민(JongMin Lee) 한국정보과학회 1996 한국정보과학회 학술발표논문집 Vol.23 No.2A

무선통신(wireless communication)기술의 발달은 사용자가 이동중에도 데이타베이스에 계속 접근할 수 있는 이동 컴퓨팅 환경을 가능하게 하였다. 이러한 이동 컴퓨팅 환경에서는 사용자의 이동성과 잦은 접속단절 등의 문제에 대처할 수 있는 캐쉬 관리 기법이 요구된다. 이 논문에서는 이동 호스트와 지구국 사이에서는 탐지(detection)기반의 NWL-MH(No-Wait Locking for Mobile Host) 규약(protocol)을 사용하고, 지구국들 사이에서는 회피(avoidance)기반 O2PL(Optimistic Two Phase Locking) 규약을 사용하는 2단계 캐쉬 관리 기법을 제시한다. 그리고 무선통신에서는 매우 제한적인 대역폭(bandwidth)의 효율적인 사용을 위해, 잠금(lock) 상속의 개념을 도입하여 메시지의 수를 줄이도록 하였다. 제안하는 2단계 캐쉬 관리 기법은 이동 컴퓨팅 환경의 특성에 적합하며, 그 환경에서의 트랜잭션 처리에 대한 메시지 비용을 최소화할 수 있다.

고압 연료분사용 피에조 액츄에이터 모델링 및 유압 동특성 해석

김민식(Minsik Kim),이광성(Gwangseog Lee),이중협(Junghyup Lee),이진욱(Jinwook Lee),유호선(Hoseon Yoo),김문헌(Munheon Kim) 한국자동차공학회 2011 한국자동차공학회 부문종합 학술대회 Vol.2011 No.5

In this study, a piezo-driven injector, as a new method driven by piezoelectric energy, has been designed and investigated based on the concept of inverse piezo-electric effect to overcome the major drawbacks of conventional solenoid-driven injector. So it has been applied with a purpose to develop the analysis model of the piezo actuator to predict the dynamics characteristics of the hydraulic component(injector) by using the AMESim code. Aimed at simulating the hydraulic behavior of the piezo-driven injector, the circuit model has been developed and verified by comparison with the experimental results. The effects of an electric control between the solenoid valve and piezo-ceramic stack for injector needle’s driving on the dynamic characteristics were usually investigated. As this research results, we found that the input voltage exerted on piezo stack is the dominant factor and the piezo-driven injector has more degrees of freedom in controlling the fuel injection with the high pressure than a solenoid-driven injector.

개질된 표면을 이용한 풀비등 임계열유속 증진에 관련한 실험적 연구

강순호(Soonho Kang),안호선(Hoseon Ahn),조항진(Hangjin Jo),김무환(MooHwan Kim),김형모(Hyungmo Kim),김준원(Joonwon Kim) 대한기계학회 2009 大韓機械學會論文集B Vol.33 No.11

In the boiling heat transfer mechanism, CHF(critical heat flux) is the significantly important parameter of the system. So, many researchers have been struggling to enhance the CHF of the system in enormous methods. Recently, there were lots of researches about enormous CHF enhancement with the nanofluids. In that, the pool boiling CHF in nanofluids has the significantly increased value compared to that in pure water because of the deposition of the nanoparticle on the heater surface in the nanofluids. The aim of this study is the comparison of the effect of the nanoparticle deposited surface and the modified surface which has the similar morphology and made by MEMS fabrication. The nanoparticle deposited surface has the complex structures in nano-micro scale. Therefore, we fabricated the surfaces which has the similar wettability and coated with the micro size post and nano structure. The experiment is performed in 3 cases : the bare surface with 0.002% water-ZnO nanofluids, the nanoparticle deposited surface with pure water and the new fabricated surface with pure water. The contact angle, a representative parameter of the wettability, of the all 3 cases has the similar value about 0 and the SEM(scanning electron microscope) images of the surfaces show the complex nano-micro structure. From the pool boiling experiment of the each case, the nanoparticle deposited surface with pure water and the fabricated surface with pure water has the almost same CHF value. In other words, the CHF enhancement of the nanoparticle deposited surface is the surface effect. It also shows that the new fabricated surface follows the nanoparticle deposited surface well.

Examining Patterns of Polypharmacy in Bipolar Disorder: Findings from the REAP-BD, Korea

Kiwon Kim,Hyunju Yang,Euihyeon Na,Hoseon Lee,Ok-Jin Jang,Hyung-Jun Yoon,Hong Seok Oh,Byung-Joo Ham,Seon-Cheol Park,Shih-Ku Lin,Chay Hoon Tan,Naotaka Shinfuku,Yong Chon Park 대한신경정신의학회 2019 PSYCHIATRY INVESTIGATION Vol.16 No.5

Based on Korean data from the Research on Asian Psychotropic Prescription Pattern for Bipolar Disorder, this study tried to present prescription patterns in biopolar disorder (BD) and its associated clinical features. Based on the information obtained from the study with structured questions, the tendency of prescription pattern was studied and analyzed. Polypharmacy was predominant, including simple polypharmacy in 51.1% and complex polypharmacy in 34.2% of patients. Subjects associated with simple or complex polypharmacy were significantly younger, had higher inpatient settings, a larger portion of onset with manic episode, a shorter duration of untreated illness, a shorter duration of current episode, were more overweight, used less antidepressants and used more anxiolytics. These findings can suggest higher polypharmacy rate in more severe BD and highlight the necessity of monitoring the weight of subjects with polypharmacy.

주파수 기반 UWB 시스템의 펄스 동기 방법

최호선(Hoseon Choi),장동헌(Dongheon Jang),안동헌(Donghun An),양훈기(Hoongee Yang),양성현(Seonghyeon Yang),강문식(Moonsik Kang),김세중(Sejung Kim) 한국통신학회 2008 韓國通信學會論文誌 Vol.33 No.3A

본 논문은 주기적인 펄스열 형태의 동기 신호로 부터 주파수 성분들을 추출한 후 이를 이용해서 디지털적으로 구현 가능한 UWB 신호 동기 검출 방법을 제시한다. 동기 신호의 펄스 개수 및 펄스 간격이 동기 검출 성능에 미치는 영향 및 제시된 방법으로 얻을 수 있는 동기의 정확도를 이론적으로 분석한다. 또한, 시뮬레이션을 통하여 이론적 분석 결과를 검증하고 AWGN 환경에서의 제시된 방법의 성능을 보인다. In this paper, we propose a digitally implementable synchronization method for the UWB system. This is achieved by manipulating the frequency components of a synchronizing signal which is the sequence of pulses of periodicity. We analyze the dependancy of the number of pulses and pulse interval on the intrinsic synchronization accuracy. Moreover, through the computer simulation, the performance of the proposed method is examined via varying system parameters.

구조적 제약조건을 갖는 500 MW 석탄화력발전소 탈황설비의 성능개선

김종성,유호선,Kim, Jong-Sung,Yoo, Hoseon 한국플랜트학회 2019 플랜트 저널 Vol.15 No.4

미세먼지 감축에 대한 사회적 요구 증가와 강화되는 대기오염물질 배출허용기준을 충족시키기 위해 구조적 제약조건을 갖는 500 MW급 석탄화력발전소 탈황설비의 성능개선 방안을 제시하였다. 탈황설비 흡수탑을 통과하는 배기가스가 선회하도록 내부 설비를 개조하여 난류를 형성시켜 물질전달효율을 증가시키고 반응 면적 및 시간을 증가시킴으로써 황산화물 저감 및 먼지 포집 능력을 향상시킬 수 있었다. 개선결과 황산화물 제거효율은 91.61%에서 98.43%로 향상되었고 먼지 제거성능은 77.4%에서 87.08%로 향상되었다. 배출농도는 황산화물 7.85 ppm, 먼지 4.67 mg/㎥이 배출되어 2023년의 대기오염물질 배출허용기준인 황산화물 25 ppm, 먼지 5 mg/㎥을 만족하는 수준이다. 본 연구의 성능 개선 방식은 유사한 제약조건을 갖는 다른 석탄화력발전소에도 효과적으로 적용될 수 있으리라 기대된다. To meet both increasing social demand for reduction of fine dust and the strengthened air pollutant emission standards, this paper indicated performance enhancement of FGD with structural constraints in 500 MW coal fired thermal power plant's. Through modifying internal facilities for flue gases to make swirl in the absorption tower, it made turbulence and increased the efficiency of material transfer, the reaction area and time with the limestone slurry. Therefore, it could reduce dust and enhance the performance of collecting the SO₂. As a result, desulfurization efficiency was improved from 91.61% to 98.43% and dust removal efficiency was improved from 77.4% to 87.08%. Emission density is 7.85 ppm of SO₂ and 4.67 mg/㎥ of dust. This is a level that satisfies emission limit of 25 ppm of SO₂ and 5 mg/㎥ of dust which are the air pollutant emission standards of 2023. The performance enhancement method of this study is expected to be effectively applied to other coal-fired power plants with similar constraints.

Development of dry-origin latent footwear impression on non-porous and semi-porous surfaces using a 5-methylthioninhydrin and L-alanine complex

Hong, Sungwook,Kim, Yeounjeung,Park, Jihye,Lee, Hoseon The Korean Society of Analytical Science 2017 분석과학 Vol.30 No.2

5-methylthioninhydrin (5-MTN) is an amino acid sensitive reagent used for the development of latent fingermarks deposited on porous surfaces such as paper and wood. The present study demonstrates that the 5-MTN can be used as a latent footwear impression enhancement reagent, by reacting with trace multivalent metal ions, which are the main components of the latent footwear impression. 5-MTN and L-alanine complex (MTN-ALA) used for the latent footwear impression development was prepared, by mixing $4.5{\times}10^{-3}M$ 5-MTN (in methanol) and $4.5{\times}10^{-3}M$ L-alanine (in methanol) in 1:1 ratio, and keeping undisturbed at room temperature for 24 h. The latent footwear impressions were deposited on white and black non-porous surfaces (glass plate, polyethylene panel, polypropylene panel, acryl panel, polyvinyl chloride (PVC) panel, poly(methyl methacrylate) (PMMA) panel, acrylonitrile-butadiene-styrene (ABS) panel, tile), and a semi-porous surfaces (painted wood). The latent footwear impressions on these surfaces were treated with MTN-ALA complex by spraying. The fluorescence of footwear impressions (occurred due to the reaction between MTN-ALA and metal complexes) was observed under a 505 nm forensic light source and an orange barrier filter. The enhancement of latent footwear impression was achieved from black surfaces without any blurring. However, the fluorescence (enhancement) of footwear impression was not observed on the white PVC, PMMA, and ABS surfaces, because the incident light interfered and reflected on the surface. The sensitivity of MTN-ALA was superior to 2,2'-dipyridil, which is a representative non-fluorescing footwear impression enhancement reagent, and similar to 8-hydroxyquinoline, which is a representative fluorescing footwear impression enhancement reagent.