Zinc–Phosphorus Complex Working as an Atomic Valve for Colloidal Growth of Monodisperse Indium Phosphide Quantum Dots

Koh, Sungjun,Eom, Taedaehyeong,Kim, Whi Dong,Lee, Kangha,Lee, Dongkyu,Lee, Young Kuk,Kim, Hyungjun,Bae, Wan Ki,Lee, Doh C. American Chemical Society 2017 Chemistry of materials Vol.29 No.15

<P>Growth of monodisperse indium phosphide (InP) quantum dots (QDs) represents a pressing demand in display applications, as size uniformity is related to color purity in display products. Here, we report the colloidal synthesis of InP QDs in the presence of Zn precursors in which size uniformity is markedly enhanced as compared to the case of InP QDs synthesized without Zn precursors. Nuclear magnetic resonance spectroscopy, X-ray photoelectron spectroscopy, and mass spectrometry analyses on aliquots taken during the synthesis allow us to monitor the appearance of metal phosphorus complex intermediates in the growth of InP QDs. In the presence of zinc carboxylate, intermediate species containing Zn-P bonding appears. The Zn-P intermediate complex with P(SiMe3)(3) exhibits lower reactivity than that of the In P complex, which is corroborated by our prediction based on density functional theory and electrostatic potential charge analysis. The formation of a stable Zn P intermediate complex results in lower reactivity, which enables slow growth of QDs and lowers the extreme reactivity of P(SiMe3)(3), hence monodisperse QDs. Insights from experimental and theoretical studies advance mechanistic understanding and control of nucleation and growth of InP QDs, which are key to the preparation of monodisperse InP-based QDs in meeting the demand of the display market.</P>

Reconfigurable spintronic physical unclonable functions based on spin-orbit torques in ferromagnet/nonmagnet/ferromagnet trilayer structures

Soogil Lee,Jaimin Kang,Jeong-Mok Kim,Taek-Hyeon Lee,Sungjun Lee,Donghyeon Han,Sanghwa Lee,Kab-Jin Kim,Byong-Guk Park 한국자기학회 2021 한국자기학회 학술연구발표회 논문개요집 Vol.31 No.1

Entering the era of Inter of Things (IOT), diverse smart devices generate and transfer enormous digital information. In this IOT environment, information security is becoming a critical issue because conventional software-based security technology is vulnerable to adversarial machine learning attacks. Thus, hardware-based security technology has been proposed to overcome this vulnerability, receiving much attention as an alternative. Especially, randomness of nature serves as an essential ingredient for the hardware-based security technology. For example, manufacturing processes of complementary-metal-oxide-semiconductor (CMOS) involves inevitable tolerances. Therefore, every electronic device is physically not identical despite the identical manufacturing processes. Those distinguishable device characteristics under the identical manufacturing process, so called “physical unclonable function (PUF)”, can potentially create non-identical output (response) under the identical input (challenge) generating unique identification of each electronic devices [1]. In this presentation, we demonstrate the spintronic PUF utilizing bottom-ferromagnet (FM)/nonmagnet/top-FM trilayer structures. Here, bottom and top FMs exhibit in-plane and perpendicular magnetic anisotropy, respectively. In these trilayer structures, field-free magnetization switching of top-FM is achieved by out-of-plane polarized spin current injection due to the interfacial spin precession mechanism, and the switching polarity is controlled by the in-plane magnetization direction of bottom-FM [2]. Under the identical demagnetization process of the bottom-FM, distinct magnetic domain distributions are formed on each identical wafer, consisting of a number of Hall-bar devices with random magnetization direction of bottom-FM along the demagnetization axis. These randomly distributed domains of bottom-FM on each wafer are electrically detected through the current-induced field-free spin-orbit torque switching polarity relies on the direction of bottom-FM. Therefore, these spintronic PUF wafers with unique pattern of domain distributions manifests itself as the unique electrical identification which can also be integrated into magnetic random access memory. Furthermore, we also discuss the reconfigurability and reliability of this spintronic PUF, providing great potential to hardware-based security applications because it is compatible with current CMOS technology.

드론 기반 병충해 예찰을 위한 통합 관제 시스템 설계

이대현 ( Daehyun Lee ),한길수 ( Kilsu Han ),이현동 ( Hyundong Lee ),김국환 ( Gookhwan Kim ),이명훈 ( Meonghun Lee ),김점순 ( Jeomsoon Kim ),홍성준 ( Sungjun Hong ),이경재 ( Kyongjae Lee ),송장훈 ( Janghoon Song ) 한국농업기계학회 2017 한국농업기계학회 학술발표논문집 Vol.22 No.2

최근 국내농업은 지구 온난화에 따른 기후변화와 국가 간 교역 확대, 해외여행 증가 등으로 인해 농산물 수입이 지속적으로 확장되고 있으며, 이는 검역병해충 및 외래·돌발 병해충의 발생 확산을 야기하여 농가의 병충해 피해를 증가시키고 있다. 특히, 이 중 과수 화상병의 경우 빠른 전염속도로 인해 발생 시과수원을 폐원시키므로 농가의 심각한 피해를 가져다주고 있어 문제해결이 시급한 실정이다. 국내에서는 병충해 관리를 위해 정기적인 예찰 및 방제를 수행하고 있지만 인력 활용 및 육안으로 감염 여부를 판정하고 있어 정확한 예찰이 어려울 뿐만 아니라 인력에 의한 병의 전파가 지속적으로 우려되고 있다. 드론은 무인비행장치로 최근 비행 제어 기술의 고도화로 인해 다양한 산업에서 그 활용범위가 급속도로 향상되고 있다. 농업분야의 경우 영상 장치의 소형화, 경량화를 통해 다양한 영상센서를 드론에 장착함으로써 농지의 다양한 정보의 실시간 측정이 가능하다. 따라서 본 연구에서는 드론 기반 항공 예찰을 위한 기초 연구로 항공예찰 영상의 분석 및 드론 이착륙 관리를 위한 통합 관제 시스템을 설계하였다. 통합 관제 시스템은 드론 이착륙을 위한 스테이션과 항공영상 수신 및 제어 신호 송신, 항공영상 DB 관리 및 영상 분석이 가능한 데이터 처리부로 구성된다. 이착륙 스테이션은 드론 보관을 위한 케이스 내부에 드론이착륙 지원을 위한 상하 리프트 제어와 착륙 플레이트, 기구부 등이 설치되며, 드론의 이착륙에 따라 루프가 자동 개폐되도록 설계되었다. 데이터 관리부는 수신된 항공 영상을 위치-예찰정보로 데이터베이스화한 후 이를 이용하여 영상학습 모델 기반 과수병 예찰영상 분석을 수행한다. 학습 영상 데이터는 각각의 항공 영상을 분할하여 훈련, 검증, 테스트 데이터로 분류하며, 훈련 데이터는 샘플 수 증가 및 오버피팅(over-fitting) 감소를 위해 잘라내기, 회전, 밝기/색상 변환 등 데이터 증강 후 사용된다. 영상학습 기반예찰 기술의 적용성은 사과 과수 화상병 항공영상을 이용하여 적용 가능성을 평가하였다. 본 시스템을 활용한 예찰 수행 시 인력 예찰 문제 해결 및 과수원의 항공영상 정보 수집의 자동화가 가능할 것으로 예측되며, 이를 위해서는 과수병 증상이 발현된 항공영상 관련 데이터베이스 구축을 통한 예찰 모델 정확도 향상과 최적화된 드론의 운행 제어를 통한 항공 예찰의 효율 향상이 필요할 것으로 판단된다.

Highly luminescent silica-coated CdS/CdSe/CdS nanoparticles with strong chemical robustness and excellent thermal stability

Wang, Nianfang,Koh, Sungjun,Jeong, Byeong Guk,Lee, Dongkyu,Kim, Whi Dong,Park, Kyoungwon,Nam, Min Ki,Lee, Kangha,Kim, Yewon,Lee, Baek-Hee,Lee, Kangtaek,Bae, Wan Ki,Lee, Doh C IOP 2017 Nanotechnology Vol.28 No.18

<P>We present facile synthesis of bright CdS/CdSe/CdS@SiO<SUB>2</SUB> nanoparticles with 72% of quantum yields (QYs) retaining ca 80% of the original QYs. The main innovative point is the utilization of the highly luminescent CdS/CdSe/CdS seed/spherical quantum well/shell (SQW) as silica coating seeds. The significance of inorganic semiconductor shell passivation and structure design of quantum dots (QDs) for obtaining bright QD@SiO<SUB>2</SUB> is demonstrated by applying silica encapsulation via reverse microemulsion method to three kinds of QDs with different structure: CdSe core and 2 nm CdS shell (CdSe/CdS-thin); CdSe core and 6 nm CdS shell (CdSe/CdS-thick); and CdS core, CdSe intermediate shell and 5 nm CdS outer shell (CdS/CdSe/CdS-SQW). Silica encapsulation inevitably results in lower photoluminescence quantum yield (PL QY) than pristine QDs due to formation of surface defects. However, the retaining ratio of pristine QY is different in the three silica coated samples; for example, CdSe/CdS-thin/SiO<SUB>2</SUB> shows the lowest retaining ratio (36%) while the retaining ratio of pristine PL QY in CdSe/CdS-thick/SiO<SUB>2</SUB> and SQW/SiO<SUB>2</SUB> is over 80% and SQW/SiO<SUB>2</SUB> shows the highest resulting PL QY. Thick outermost CdS shell isolates the excitons from the defects at surface, making PL QY relatively insensitive to silica encapsulation. The bright SiO<SUB>2</SUB>-coated SQW sample shows robustness against harsh conditions, such as acid etching and thermal annealing. The high luminescence and long-term stability highlights the potential of using the SQW/SiO<SUB>2</SUB> nanoparticles in bio-labeling or display applications.</P>

A Study on the Improvement of Natural Regeneration DPF Regeneration for Large-Scale Diesel Vehicles

Sungjun Lee(이성준),Geomseung Han(한검승),Heung-sik Lee(이흥식),Sungyong Ha(하성용) 한국자동차공학회 2021 한국자동차공학회 부문종합 학술대회 Vol.2021 No.6

Comparison of Pitching Kinematics between Normal-Weight and Overweight Group in High School Baseball Pitchers

( Sungjune Lee ),( Hyeree Kim ),( Jaebum Park ) 한국스포츠정책과학원 2023 International Journal of Applied Sports Sciences Vol.35 No.1

This study compared differences in pitching kinematics between normal-weight and overweight high school baseball pitchers. Twenty male pitchers were included in the study. According to the 2020 guidelines on the Body Mass Index (BMI) standard for children and adolescents by the Korean Society for the Study of Obesity, 10 participants with BMI below the 85% percentile were assigned to the normal-weight group, and 10 participants with BMI above the 85% percentile were assigned to the overweight group. The two groups threw 10 trials for a fastball with maximum effort. Out of 10 trials, three pitches thrown in the strike zone with the fastest velocity were extracted. The mean ball velocity was measured, and the mean and maximum angle and angular velocity of the knee, pelvis, trunk, shoulder, and elbow joints were calculated. The differences in the ball velocity, angle, and angular velocity between the two groups were compared using an independent t-test (p<0.05). There were no differences in mean ball velocity between the two groups. However, compared with the normal-weight group, the overweight group showed smaller knee flexion, trunk forward tilt, trunk rotation, maximum trunk angular velocity, shoulder external rotation and maximum shoulder external rotation, while shoulder abduction and maximum elbow flexion were greater. These results suggest that the overweight group may have a high risk of soft tissue damage in the knee, shoulder, and elbow joints caused by limited movement of the trunk and inefficient movement between the extremities during power pitching.

Impact of Intolerance of Uncertainty on Brain Structural Changes in Panic Disorder

Sungjun Ahn,Sang-Hyuk Lee,Kang Soo Lee 대한신경정신의학회 2023 PSYCHIATRY INVESTIGATION Vol.20 No.11

Objective This study investigated the impact of intolerance of uncertainty (IU) on structural changes in the brain and symptom severity in patients with panic disorder.Methods This study included 90 participants diagnosed with panic disorder. The IU Scale, Panic Disorder Severity Scale (PDSS), Beck Depression Inventory-II (BDI-II), Penn State Worry Questionnaire (PSWQ), Self-Forgiveness Scale (SFS), and Short Form 36 Health Survey (SF) were used. A voxel-wise correlation analysis was conducted to investigate the structural differences in the gray matter.Results As IU increased, the cortical thickness of the right lingual gyrus decreased significantly, while the gray matter volume of the right pars triangularis increased. The cortical thickness of the right lingual gyrus showed a significant negative correlation with the BDI-II score and a positive correlation with the SFS. Additionally, the gray matter volume of the right pars triangularis was positively correlated with the PDSS, PSWQ, and BDI-II scores and negatively correlated with the mental health domain of the SF.Conclusion According to our findings, elevated IU in participants with panic disorder was associated with cortical thinning in the lingual gyrus and increased gray matter volume in the pars triangularis. These structural alterations may also have an impact on perceived quality of life, as well as high levels of depression and anxiety.

Tailoring the oxygen vacancy of cobalt-iron based electrocatalysts for OER via the mechanochemistry

Sungjun Heo,Chiho Kim,Song Jin,Jae-Yeop Jeong,Shinwoo Myeong,Hoseok Lee,Eonju Park,Namin Kim,Jae-hun Lee,Jun young park,Jooyoung Lee,Sung Mook Choi 한국표면공학회 2023 한국표면공학회 학술발표회 초록집 Vol.2023 No.11-1

Sulfonium-based organic structure-directing agents for microporous aluminophosphate synthesis

Lee, Sungjune,Jo, Changbum,Park, Hongjun,Kim, Jaeheon,Ryoo, Ryong Elsevier 2019 Microporous and mesoporous materials Vol.280 No.-

<P><B>Abstract</B></P> <P>Sulfur-centered phenyl, <I>n</I>-butyl, <I>p</I>-tolyl, and benzyl sulfoniums and sulfides were tested as organic structure-directing agents (SDAs) for the synthesis of crystalline microporous aluminophosphates (AlPOs) over various ranges of gel compositions, hydrothermal treatment temperatures, and crystallization times. Among the investigated compounds, triphenylsulfonium gave single-phase products of ATS-type AlPO and silicoaluminophosphate. Other sulfoniums yielded only non-porous, dense crystalline AlPOs. On the other hand, diaryl sulfides gave a tiny amount of AFI-type AlPO amid tridymite and amorphous phases. Based on the results, it was found to be reasonable that weakly basic sulfide could hardly act as a zeotype SDA due to the low protonation to sulfonium at the present synthesis pH.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Various sulfoniums and sulfides were tested as SDAs for synthesis of zeotype AlPOs. </LI> <LI> Triphenylsulfonium hydroxide SDA gave single-phase ATS-type AlPO and SAPO. </LI> <LI> Sulfides were unsuitable to serve as an AlPO SDA due to insufficient basicity for protonation. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Gait Recognition Using Decision-Level Fusion

Sungjun Hong,Heesung Lee,Byungyun Lee,Euntai Kim 대한전자공학회 2010 ICEIC:International Conference on Electronics, Inf Vol.1 No.1

For human identification, in this paper, a gait recognition system adopting decision-level fusion is proposed. The gait sequence obtained from a video camera is partitioned into multiple gait cycles selecting key frames summarizing a single stride. After gait cycle partitioning, the projection of a silhouette image called as a frieze pattern is calculated as a gait feature. To identify individual, the outputs of the nearest neighbor classifiers are fused by majority voting. To demonstrate the validity of the proposed method, the CASIA gait dataset A are used to evaluate the recognition performance.