SBW 액추에이터용 SRM의 토크리플 저감을 위한 회전자 형상 설계

이창민(Changmin LEE),정재식(Jaesik JEONG),이희락(Heerak LEE),이종찬(Jongchan LEE),홍성현(Sunghyun HONG),조종환(Jonghwan CHO),이동수(Dongsu LEE) 대한전기학회 2020 대한전기학회 학술대회 논문집 Vol.2020 No.10

A Driving Simulation Study for the Effects of Divided-Attention on Driving Performance: Comparison of Young and Old Drivers

Lee,Jaesik 한국자료분석학회 2003 Journal of the Korean Data Analysis Society Vol.5 No.4

To investigate the effect of divided attention on driving behavior, the present study performed a driving simulation with different age group. The subjects were asked to drive the driving simulator as their normal driving when their attention was systematically distracted by different sensory modality (visual vs. auditory) and distraction level (simple vs. complex). Free recall performance was also measured to investigate the drivers ability to process information under the task requirement. The results showed the following results: First, when the every distraction conditions (visual-complex, visual-simple, auditory-complex, and auditory-simple) were compared with the no-distraction condition, the driving performance for both age group generally decreased when the any kinds of distracter were presented. Second, the age effect was significant in the most driving performance measures. Third, the distraction of visual modality or the complex distracters generally produced more larger driving performance impairment than the auditory or simple distraction condition. Fourth, the complexity of distracter was more important factor in free recall task than modality factor for both age group. Finally, the results are discussed in terms of strength, limitation, and implication of the present study.

Flip Chip Bump Formation of Sn–1.8Bi–0.8Cu–0.6In Solder by Stencil Printing

Lee, Jaesik,Jung, Jae-Pil,Cheon, Chu-Seon,Zhou, Yunhong,Mayer, Michael The Japan Institute of Metals 2005 Materials transactions Vol.46 No.11

<P>Flip chip bumping by stencil printing method using a new composition of solder paste, Sn–1.8%Bi–0.8%Cu–0.6%In, all in mass%, was investigated. Sn–3.5%Ag, Sn–37%Pb and Sn–36%Pb–2%Ag were selected as references for the experiment. The solder pastes were printed on the under bump metallization (UBM) of a Si-wafer using a stencil, where diameter and thickness of the stencil opening were 400 and 150 μm, respectively. The UBM deposit comprised 0.4 μm each of Al, Ni and Cu, and 20 nm of Au from bottom to top of the metallization, sequentially. The printed paste bumps were reflow soldered in air, and the peak soldering temperature of Sn–1.7Bi–0.8Cu–0.6In and Sn–3.5Ag was 523 K and of Sn–37Pb and Sn–36Pb–2Ag was 503 K. From the experimental results the solder bumps of Sn–1.8Bi–0.8Cu–0.6In alloys were well-formed with a mean height of 260 μm. The shear strength of Sn–1.8Bi–0.8Cu–0.6In at 523 K (as-reflowed) showed the highest value of 6.5N followed by those of Sn–3.5Ag, Sn–37Pb and Sn–36Pb–2Ag solders. After 1000 h aging, while the shear strength of the Sn–1.8Bi–0.8Cu–0.6In showed 27% decrease compared to as-reflowed conditions, it was still 15–30% higher than those of Sn–37Pb, Sn–36Pb–2Ag and Sn–3.5Ag solders. Intermetallic compounds (IMCs) formed on the interface between solder and UBM were (Cu,Ni)<SUB>6</SUB>Sn<SUB>5</SUB>. As aging time went on up to 1000 h, the content of Ni in the IMC changed from 6.6% at initial stage (as-reflowed) to 13.5% at final stage (1000 h aging).</P>

Integration of Graphene Oxide on Nylon/Polyester/Cotton Fabrics for a Wearable Electronic Nose Sensor

Lee, Eunji,Chung, Yoonsung,Lee, Doohee,Yoon, Jaesik,Lincoln, Christopher,Prorok, Bart Charles,Woo, Sungpil,Yoon, Young Soo,Kim, Dong-Joo The Electrochemical Society 2017 ECS transactions Vol.77 No.11

<P>This work presents a facile solution method to fabricate graphene oxide (GO) on fabrics for a wearable electronic nose sensor. Three types of fabrics such as nylon, polyester, and cotton were used as wearable substrates. Thin PVC film was laminated on the fabrics to promote deposition of electrodes on the fabrics. To determine types of solution for constructing GO on the fabrics, water and ethanol were compared as typical solvents to disperse GO. Water distributed GO nanoflake was uniformly coated on the fabrics by simple drop coating. Room temperature gas sensing was examined with GO integrated on the fabrics, and it exhibited n-type gas sensing behavior on 100 ppm ammonia and its response showed comparable values in resistance change with flat substrates.</P>

Excellent Switching Uniformity of Cu-Doped <tex> $\hbox{MoO}_{x}/\hbox{GdO}_{x}$ </tex> Bilayer for Nonvolatile Memory Applications

Jaesik Yoon,Hyejung Choi,Dongsoo Lee,Ju-Bong Park,Joonmyoung Lee,Dong-Jun Seong,Yongkyu Ju,Man Chang,Seungjae Jung,Hyunsang Hwang IEEE 2009 IEEE electron device letters Vol.30 No.5

<P>We have investigated a Cu-doped MoO<SUB>x</SUB>/GdO<SUB>x</SUB> bilayer film for nonvolatile memory applications. By adopting an ultrathin GdO<SUB>x</SUB> layer, we obtained excellent device characteristics such as resistance ratio of three orders of magnitude, uniform distribution of set and reset voltages, switching endurance up to 10<SUP>4</SUP> cycles, and ten years of data retention at 85degC. By adopting bilayer films of Cu-doped MoO<SUB>x</SUB>/GdO<SUB>x</SUB>, a local filament was formed by a two-step process. Improved memory characteristics can be explained by the formation of nanoscale local filament in the ultrathin GdO<SUB>x</SUB> layer.</P>

조직의 안전실천에 대한 평가와 안전행동 사이의 관계

이재식(Jaesik Lee) 인문사회과학기술융합학회 2018 예술인문사회융합멀티미디어논문지 Vol.8 No.9

산업재해는 국가, 조직, 개인 차원 모두에서 큰 손실을 가져올 뿐만 아니라 근로자의 삶의 질을 저해하는 가장 중요한 요인 중 하나이다. 본 연구에서는 308명의 생산직 근로자들을 대상으로 설문지기법을 통해 조직의 안전분위기를 결정짓는 주요 요인 중 하나인 조직의 안전실천에 대한 작업현장근로자의 평가와 이들의 안전행동 사이의 관련성 및 이 두 가지 변인 사이의 관련성을 조절하는 직무관여의 효과를 상관분석과 위계적 회귀분석을 사용하여 분석하였다. 본 연구의 결과를 요약하면 다음과 같다. 먼저, 연구 참여자들의 인구통계학적 특성과 다른 변인들의 상관관계 분석 결과, 연령이나 근속연수가 높을수록 조직의 안전실천에 대한 평가가 긍정적이고, 직무관여 수준이 높으며 안전행동수준도 높았다. 둘째, 근로자들이 조직의 안전실천에 대해 긍정적으로 평가할수록, 그리고 직무관여 수준이 높을수록 안전행동을 수행하는 경향이 컸다. 셋째, 전반적으로 보면 안전실천에 대한 평가가 긍정적일수록 안전행동을 준수하는 경향이 유의하게 높았으나 이러한 경향은 직무관여 수준이 높을수록 더 뚜렷하였다. 이러한 결과는 조직에서 근로자의 안전행동을 유도하기 위해서는 안전규정을 포함한 안전실천의 효율적 시행이나 교육과 함께 근로자 직무관여를 높이는 방안이 동시에 모색되어져야 한다는 것을 시사한다. Industrial accidents can bring serious national, organizational, and personal loss. And it is one of a most influencing factors which can deteriorate individual’s well-being. This study investigated the relationship between employee’s subjective evaluation for organizations’s safety practice and safety behavior, and the moderating effect of job involvement on the relationship. Subjective rating scores for safety practice evaluation, safety behavior, and job involvement were collected from 308 in-field workers and analyzed by using correlation analysis and hierarchical regression. The results are as follows. First, the workers’ age and years of employment were positively correlated with positive evaluation for safety practice, job involvement, and safety behavior. Second, the participants showed higher score of safety behavior as they evaluated safety practice more positively and involved in their job. Third, most importantly, it was found that job involvement significantly moderated the relationship between safety practice and safety behavior. That is, this tendency was more prominent in higher job involvement condition than in lower job involvement condition. The results suggested that increasing job involvement in organization is very crucial to enhance worker’s safety behavior.

고령운전자에 대한 선택반응 반복훈련 효과

이재식(Jaesik Lee) 한국자료분석학회 2021 Journal of the Korean Data Analysis Society Vol.23 No.1

본 연구는 손 반응과 발 반응을 구분한 선택반응 과제에 대한 반복훈련이 고령운전자들의 반응시간과 반응정확성에서 어떠한 양상의 변화를 가져오는지 살펴보기 위해 수행되었다. 날을 달리한 5회의 훈련회기에 걸쳐 손 반응이 요구되는 2개 자극과 발 반응이 요구되는 2개 자극을 무선적으로 제시한 후 고령운전자들이 5회의 훈련회기에 걸쳐 보인 자극 선택반응에서의 반응속도, 반응정확성, 반응시간 변산성 및 오반응 유형별 빈도에서의 변화를 종속치로 분석하였다. 주요 결과를 요약하면 다음과 같다. 첫째, 전반적으로 실험참가자들은 훈련회기의 진행에 따라, 그리고 발 반응보다는 손 반응에서 더 빠르고, 정확하게, 그리고 더 작은 반응시간 변산성으로 반응하였다. 둘째, 손 반응의 경우 훈련회기의 진행에 따라 반응시간과 반응시간 변산성이 점진적 으로 감소한 반면, 발 반응의 경우는 특정 훈련회기까지 급속한 감소를 보인 후 더 이상의 향상을 보이지 않았다. 셋째, 발 선택 오반응은 손 선택 오반응에 비해 세 배 정도 빈도가 높았을 뿐만 아니라 훈련회기가 진행되어도 수행에서의 향상이 관찰되지 않았다. 이러한 결과는 고령운전 자에 대한 반복적 선택반응 훈련이 반응의 속도와 정확성에서 전반적인 향상을 가져오기는 하지만 브레이크와 액셀러레이터를 서로 혼동하여 잘못 선택하는 등의 특정 오반응은 반복적 훈련에 의해서도 향상되기 힘들 수 있다는 것을 시사한다. This study examined how the repetitive training for choice response task changes response time and accuracy of elderly drivers. Two stimuli requiring a hand-response and 2 stimuli requiring a foot-reaction were presented over 5 training sessions. Response speed, response accuracy, reaction time variability, and frequency of error types were analyzed as dependent values. The main results are summarized as follows. First, participants showed faster, more accurate, and less variability in reaction time with the progress of the training session and in hand-response than foot-response. Second, hand-response resulted in gradually decreased reaction time and variability of reaction time as the training session progressed, whereas in the case of foot-response, after a rapid decrease until a specific training session, there was no further improvement. Third, in the foot-selection condition, the frequency of false reactions was higher than in the hand-selection condition, and no improvement was observed in performance even after the training session progressed. These results suggested that although repetitive choice response training for elderly drivers results in an overall improvement in the speed and accuracy of the reaction, certain response error, such as confusing brake and accelerators with each other, may be difficult to be improved even by repeated training.

중다 반응시간 과제에 기반한 중년, 고령 및 뇌졸중 고령 운전자의 반응시간과 반응정확성에서의 차이 비교

이재식 ( Jaesik Lee ),주미정 ( Mijung Joo ),김정호 ( Jung-ho Kim ),김영근 ( Young-keun Kim ),이원영 ( Won-young Lee ),류준범 ( Jun-beom Ryu ),오주석 ( Ju-seok Oh ) 한국감성과학회 2017 감성과학 Vol.20 No.1

본 연구는 운전자 연령대와 뇌손상 여부에 따라 다양한 반응시간 과제에서의 반응시간과 반응정확성에서 어떠한 차별성이 있는지 살펴볼 목적으로 수행되었다. 이를 위해 30-50대의 중년운전자, 65세 고령운전자, 그리고 65세 이상의 뇌졸중 고령운전자들을 대상으로 단순반응, 2-선택반응, 자극 이심률을 달리한 4-선택반응, 탐색반응 및 동적자극탐지 과제에 대한 수행을 비교하였다. 본 연구의 결과를 정리하면 다음과 같다. 첫째, 전반적으로 중년, 고령 및 뇌졸중 고령운전자 순으로 느린 반응시간을 보였으나 자극 이심률이 작은 조건(5^o)에 비해 큰 조건(10^o)에서 뇌졸중 고령운전자의 반응시간이 다른 집단에 비해 더 두드러지게 지연되었다. 둘째, 전체 반응시간에서 단순 반응시간을 감산한 반응시간을 분석한 결과, 2-선택반응 과제와 동적자극 탐지과제에서의 집단간 반응시간 차이는 유의하지 않았는데, 이것은 이러한 과제들에서의 반응시간 차이가 단순 반응시간에 의해 주로 결정된다는 것을 시사한다. 셋째, 일시적 기억을 요구하는 탐색과제에서는 두 고령운전자 집단이 중년운전자 집단에 비해 유의하게 느리고 부정확한 수행을 보였다. 넷째, 집단간 반응정확성에서의 차이는 선택 대안이 많은 과제와 기억을 요구하는 과제에서 두드러졌다. 이러한 결과는 기억 요구를 수반하는 탐색과제는 중년과 고령운전자 사이의 수행을, 반면 자극 이심률 조건은 뇌졸중 여부에 따른 고령운전자 집단에서의 수행 차이를 민감하게 반영할 수 있음을 시사한다. Differences in reaction time and accuracy were compared among driver groups of middle-, old-, and stroke old-age drivers using various reaction time tasks including simple reaction task, 2-choice task, 4-choice task with different stimuli eccentricity, search task, and moving target detection task. The results can be summarized as followings. First, although overall reaction time tended to be slowed with age and stroke, stroke old drivers showed significantly slower reaction time than the other driver groups when the stimuli were presented in a large eccentricity. Second, differences in reaction time for 2-choice task and moving target detection task seemed to be determined mainly by participants` simple reaction time. Third, the search task which required temporary retention of previously presented stimuli was found to be more sensitive in discriminating difference in reaction time between middle-age drivers and old-age drivers (including stroke old drivers). Fourth, reaction accuracy of old (and stroke old) drivers decreased when more stimuli alternatives were presented and temporary retention for stimuli was required. Altogether, memory demand in reaction time task can be sensitive to evaluate performance for different age groups, whereas size of useful field of view for brain stroke.

Effects of Denatured Lysozymes against Pathogenic Bacteria and Viral Hemorrhagic Septicemia Virus

Joongjae Lee,Duwoon Kim,Kwangwook Ko,JaeSik Ryu,Youngseung Lee,Yoonhwa Jeong,Misook Kim 한국식품영양과학회 2016 한국식품영양과학회 학술대회발표집 Vol.2016 No.10

중년 및 고령운전자의 지속적 횡적추적과 시각도에 따른 자극선택 수행 차이

이재식(Jaesik Lee) 한국자료분석학회 2020 Journal of the Korean Data Analysis Society Vol.22 No.6

본 연구에서는 지속적 횡적추적과 시각도를 달리한 자극의 선택반응이 동시에 요구되는 조건에서 중년운전자와 고령운전자가 보인 횡적추적에서의 에러 크기, 선택반응에서의 반응속도 및 반응정확률에서의 차이를 비교하였다. 횡적추적은 중심시 영역에서 임의의 수평방향으로 계속 이동하는 표적에 대해 휠을 이용하여 커서자극을 일치시키는 것이었다. 선택반응 과제는 5°와 10°의 시각도를 갖는 두 조건의 자극에 대해 미리 정해진 페달을 선택하여 빠르고 정확하게 반응하는 것이었다. 주요 결과는 다음과 같다. 첫째, 고령운전자 집단은 중년운전자 집단에 비해 횡적추적에서 더 큰 에러를 보였다. 둘째, 고령운전자 집단은 중년운전자 집단에 비해, 그리고 자극 시각도가 작은 조건에 비해 큰 조건에서 유의하게 더 느린 반응시간과 더 낮은 반응정확률을 보였다. 특히 자극 시각도 증가에 따른 반응시간에서의 증가폭은 중년운전자 집단에 비해 고령운전자 집단에서 상대적으로 더 컸으나 반응정확률에서는 이러한 상호작용 효과가 관찰되지 않았다. 이러한 결과는 중년운전자와 비교하여 고령운전자의 경우에는 횡적추적에서의 전반적 어려움뿐만 아니라 자극 시각도가 증가할수록 자극 처리에서의 수행이 더 저하될 수 있다는 것과 반응의 속도보다는 반응의 정확성에 초점을 둔 반응 방략을 사용한다는 것을 시사한다. The difference in error magnitude in the lateral tracking, the response speed and response accuracy in the selection response the middle-aged and elderly drivers were compared under continuous lateral tracking demand. The lateral tracking was to match the cursor stimulus using a wheel for a target that continuously moves in an arbitrary horizontal direction in the central vision area. In the selective response task, the drivers were instructed to respond quickly and accurately to two types of stimuli with 5° and 10° visual angles with corresponding pedals. The main results are as follows. First, the elderly drivers showed a greater error in lateral tracking than the middle-aged drivers. Second, compared to the middle-aged drivers, the elderly drivers showed significantly slower response speed and lower response accuracy in the visual angle of 5° than that of 10°. In particular, the increase in response time according to the increase in the stimulus eccentricity was relatively greater in the elderly drivers than in the middle-aged drivers, but this interaction effect was not observed in the response accuracy. These results suggested that the elderly drivers can experience the overall difficulty in lateral tracking and visual processing for peripherally presented stimuli. Also, it seemed that the elderly drivers adopt response strategy of focusing accuracy rather than speed of the response.