Electrochemical fabrication of Fe-based binary and ternary phosphide cathodes for proton exchange membrane water electrolyzer

Kim, Junhyeong,Kim, Hyunki,Kim, Jooyoung,Kim, Jung Hwan,Ahn, Sang Hyun Elsevier 2019 JOURNAL OF ALLOYS AND COMPOUNDS Vol.807 No.-

<P><B>Abstract</B></P> <P>The development of high-performance gas diffusion electrodes is essential for the fabrication of efficient proton exchange membrane water electrolyzers (PEMWEs) and thus for clean hydrogen production. Herein, we electrodeposited Fe-based binary and ternary phosphides on porous carbon paper (CP) as a substrate and demonstrated that, under optimized deposition conditions (i.e. when the P content was maximum), amorphous FeCoP showed the highest intrinsic activity for hydrogen evolution in an acidic medium. This behavior was ascribed to appropriate electronic structure modification and the alloying effect. Further enhancement of hydrogen evolution performance was achieved by increasing the electrochemical surface area of FeCoP by using a porous Cu foam (CF) support. In a half-cell test, the FeCoP/CF/CP electrode featured an acceptably stable cathodic current of −10 mA/cm<SUP>2</SUP> at an overpotential of −125 mV. A PEMWE single cell with an FeCoP/CF/CP cathode exhibited a current density of 0.95 A/cm<SUP>2</SUP> at a cell voltage of 2.0 V, which is superior to or comparable with previously reported values. Thus, the developed electrode might be a promising alternative to Pt-based cathodes in practical PEMWE applications.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Fe-based transition metal phosphides were electrodeposited on porous carbon paper. </LI> <LI> FeCoP/carbon paper (CP) showed the highest HER intrinsic activity. </LI> <LI> The electrochemical surface area of FeCoP was increased by using a Cu foam support. </LI> <LI> PEMWE with a FeCoP/CF/CP cathode featured a current density of 0.95 A/cm<SUP>2</SUP> at 2.0 V. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Role of creatine supplementation in exercise-induced muscle damage : A mini review

Jooyoung Kim,Joohyung Lee,Seungho Kim,Daeyoung Yoon,Jieun Kim,Dong Jun Sung 한국운동재활학회 2015 JER Vol.11 No.5

Nanoporous Nickel Phosphide Cathode for a High-Performance Proton Exchange Membrane Water Electrolyzer

Kim, Jooyoung,Kim, Junhyeong,Kim, Hyunki,Ahn, Sang Hyun American Chemical Society 2019 ACS APPLIED MATERIALS & INTERFACES Vol.11 No.34

<P>Hydrogen production via a proton exchange membrane water electrolyzer (PEMWE) is an essential technology to complement discontinuity of renewable energies. Development of a high-efficiency and cost-effective gas diffusion electrode (GDE), which is a key component of this technology, remains a challenge. Here, we report a high-performance Ni phosphide GDE prepared by simple electrochemical methods. Selective leaching of excess Ni in electrodeposited Ni<SUB><I>x</I></SUB>P<SUB>1-<I>x</I></SUB> enabled fabrication of a nanoporous NiP GDE with a large electrochemical surface area (ECSA). In half-cell tests, the nanoporous NiP GDE demonstrated a hydrogen-evolving current density of −10 mA/cm<SUP>2</SUP> at an overpotential of 103 mV with good stability. In the single-cell tests, the PEMWE employing a nanoporous NiP cathode exhibited a current density of 1.47 A/cm<SUP>2</SUP> at a cell voltage of 2.0 V, which was the competitive performance among state-of-the-art non-noble cathodes reported to date.</P> [FIG OMISSION]</BR>

응급의료 영역 한국어 음성대화 데이터베이스 구축

김선희(Sunhee Kim),이주영(Jooyoung Lee),최서경(Seo Gyeong Choi),지승훈(Seunghun Ji),강지민(Jeemin Kang),김종인(Jongin Kim),김도희(Dohee Kim),김보령(Boryoung Kim),조은기(Eungi Jo),김호정(Hojeong Kim),장정민(Jungmin Jang),김준형(Jun Hyung 한국음성학회 2020 말소리와 음성과학 Vol.12 No.4

본 논문은 응급의료 환경에서 음성인식 성능을 향상시키기 위하여 실제 환경에서 데이터 수집 방법을 정의하고 정의된 환경에서 수집된 데이터를 전사하는 방법을 제안한다. 그리고 제안된 방법으로 수집되고 전사된 데이터를 이용하여 기본 음성인식 실험을 진행함으로써 제안한 수집 및 전사 방법을 평가하고 향후 연구 방향을 제시하고자 한다. 모든 음성은 기본적으로 16비트 해상도와 16 kHz 샘플링으로 저장되었다. 수집된 데이터는 총 166건의 대화로서 8시간 35분의 분량이다. 수집된 데이터는 Praat를 이용하여 철자 전사, 음소 전사, 방언 전사, 잡음 전사, 그리고 의료 코드 전사를 수행하여 다양한 정보를 포함한 텍스트 데이터를 구축하였다. 이와 같이 수집된 데이터를 이용하여 기본 베이스라인 실험을 통하여 응급의료 영역에서의 음성인식 문제를 실제로 확인할 수 있었다. 본 논문에서 제시한 데이터는 응급의료 영역의 1단계 데이터로서 향후 의료 영역에서의 음성인식 모델의 학습 데이터로 활용되고, 나아가 이 분야의 음성기반 시스템 개발에 기여할 수 있을 것으로 기대된다. This paper describes a method of building Korean conversational speech data in the emergency medical domain and proposes an annotation method for the collected data in order to improve speech recognition performance. To suggest future research directions, baseline speech recognition experiments were conducted by using partial data that were collected and annotated. All voices were recorded at 16-bit resolution at 16 kHz sampling rate. A total of 166 conversations were collected, amounting to 8 hours and 35 minutes. Various information was manually transcribed such as orthography, pronunciation, dialect, noise, and medical information using Praat. Baseline speech recognition experiments were used to depict problems related to speech recognition in the emergency medical domain. The Korean conversational speech data presented in this paper are first-stage data in the emergency medical domain and are expected to be used as training data for developing conversational systems for emergency medical applications.

Smad7 Protein Induces Interferon Regulatory Factor 1-dependent Transcriptional Activation of Caspase 8 to Restore Tumor Necrosis Factor-related Apoptosis-inducing Ligand (TRAIL)-mediated Apoptosis

Hong, Suntaek,Kim, Hye-Youn,Kim, Jooyoung,Ha, Huyen Trang,Kim, Young-Mi,Bae, Eunjin,Kim, Tae Hyung,Lee, Kang Choon,Kim, Seong-Jin American Society for Biochemistry and Molecular Bi 2013 The Journal of biological chemistry Vol.288 No.5

Development of Performance Assessment Instrument for Assessing National Competency Standards (NCS) Communication Skills

Jooyoung Kim,Jaewoo Do 보안공학연구지원센터 2016 International Journal of Software Engineering and Vol.10 No.12

National Competency Standards (NCS) are defined as required knowledge, skills and attitudes needed to execute one’s duties at work; these are systematized by business sectors and level of ability. To create a competence based society, the South Korean government has established NCS and have promoted the application of NCS in vocational education areas. In accordance with the government’s effort, universities, government institutions, and companies are trying to apply NCS into their system. Particularly, universities have developed NCS-based curriculum and offer courses which are developed based on national competency standards. However, a standardized assessment tool for instructors has not been developed as of yet. With absence of an assessment instrument, instructors are struggling to assess students’ NCS vocational competency. This study developed the performance assessment instrument to assess NCS communication skills, and tested the validity of developed instrument. Developed performance assessment instrument enables the objective and coherent assessment of students’ communication skills. This study will contribute to the development of an assessment instrument for assessing other vocational basic skills.

Low-intensity tower climbing resistance exercise reduces experimentally induced atopic dermatitis in mice

Jooyoung Kim 한국운동재활학회 2019 JER Vol.15 No.4

Exploiting Metadata of Absent Object for Proxy Cache Consistency

Kim, Jooyoung,Kim, JuGyun 숙명여자대학교 자연과학연구소 2001 자연과학논문집 Vol.- No.12

웹 프락시 서버의 활용은 웹 서버로의 부하 감소와 함께 응답시간의 단축 및 트래픽의 감소를 가질 수 있다. 프락시 캐쉬의 교체와 일관성 유지를 위한 많은 연구들이 캐슁된 객체들의 메타데이터를 활용하고 있으나 현실적으로 20∼30%의 클라이언트 요구가 객체의 전송이 아닌 유효성만을 질의하는것임을 감안한다면 이 경우 프락시 서버는 메타데이타만을 유지해도 될 것이다. 본 연구는 프락시 서버에 존재하지 않는 객체라도 그것의 메타데이타와 웹 서버로 부터의 Head-only응답들을 보관하여 클라이언트의 유효성 질의에 응답함으로써 응답시간의 감소와 웹서버로의 트래픽을 줄일수 있음을 보였다. Caching at the Web proxy server plays an important role in reducing response time, the network traffic, and the load of Web servers. Many recent studies have proposed and examined the replacement and consistency policies for the proxy cache, which plays a central role in the performance of caching components. For better performance, they exploit various metadata of Web objects, such as the reference count, reference time, and modification time information of past behaviors, to estimate the re-reference likelihood and freshness of the objects. However, all of these known to the authors use the metadata only when the actual object is in the cache. We observed from various proxy traces that about 20-30% of clients' requests incurred only the validity checks of cached objects without transferring actual objects from the proxy server. In this case, only the metadata are necessary at the proxy server. This paper proposes a proxy cache consistency policy that uses the metadata even for absent objects. These include the time information of evicted objects from the cache and those out of the header-only replies from Web servers. Trace-driven simulations with public proxy cache traces show that our policy reduces the response time and the number of connections to Web servers significantly.

HS-INME-GC/MS Analysis of Phthalates using Biomass-derived Activated Hydrochar-Coated Wire

Jooyoung Kim,Sunyoung Bae 한국분석과학회 2022 학술대회논문집 Vol.2022 No.11

비파괴 측정을 위한 근접장 마이크로파 현미경 연구

김주영,김송희,유현준,양종일,유형근,유경선,김승완,이기진 한국비파괴검사학회 2004 한국비파괴검사학회지 Vol.24 No.5

근접장의 특성과 근접장 마이크로파 현미경의 배경이론을 설명하였고 유전체 공진기 제작에 앞서 HFSS (high frequency structure simulator)를 이용한 모의 시뮬레이션을 기술하였다. 이것을 바탕으로 원통형 유전체 공진기를 제작하여 금속탐침과 결합한 근접장 마이크로파 현미경(near field scanning microwave microscope : NSMM)을 구성하였다. 제작한 유전체 공진기의 특성은 HFSS를 이용하여 모의 실험한 결과와 비교하였다. Tip의 기하학적 모양에 따른 공간분해능과 감도(sensitivity)를 연구하였고 contrast가 가장 좋은 hybrid tip을 개발하였다. 전도도가 서로 다른 금속시료에 따른 NSMM의 반사계수의 변화를 측정하였고 실험결과와 이론적 시료의 임피던스를 비교하였다. 마지막으로 유전체 공진기를 이용한 NSMM으로 공간 분해능이 1μm의 Cr과 NiFe 패턴의 이미지를 비접촉, 비파괴방법으로 얻었다. We described a near-field scanning microwave microscope which uses a high-quality dielectric resonator with a tunable screw. The operating frequency is f = 4.5 5 GHz. The probe tip is mounted in a cylindrical resonant cavity coupled to a dielectric resonator. We developed a hybrid tip combining a reduced length of the tapered part with a small apex. In order to understand the function of the probe, we fabricated three different tips using a conventional chemical etching techique and observed three different NSMM images for patterened Cr films on glass substrates. We measured the reflection coefficient of different metal thin film samples with the same thickness of 300 nm and compared with theoretical impedance respectly. By tuning the tunable screw coming through the top cover, we could improve sensitivity, signal-to-noise ratio, and spatial resolution to better than 1μm. To demonstrate the ability of local microwave characterization, the surface resistance of metallic thin films has been mapped.