CVT Ratio Control for Improvement of Fuel Economy by Considering Powertrain Response Lag

Heera Lee,Hyunsoo Kim 대한기계학회 2003 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.17 No.11

A high level CVT ratio control algorithm is proposed to improve the engine performance by considering the powertrain response lag. In this algorithm, the desired CVT speed ratio is modified from the vehicle velocity, which is estimated after the time delay due to the powertrain response lag. In addition, the acceleration map is constructed to estimate the vehicle acceleration from the throttle pedal position and the CVT ratio. Using the CVT ratio control algorithm and the acceleration map, vehicle performance simulations are performed to evaluate the engine performance and fuel economy. It is found that the fuel economy can be improved about 3.6% for FUDS by the ratio control algorithm for the target vehicle. In selecting the appropriate time delay, compromise between the fuel economy and the acceleration performance is required.

Effect of 660-nm light emitting diode (LED) on the skin pigmentation before and after the ultraviolet (UV) irradiation in C57BL/6J mouse model

( Heera Lee ),( Jee Woong Choi ),( You Chan Kim ) 대한피부과학회 2021 대한피부과학회 학술발표대회집 Vol.73 No.1

Background: It has been researched that light-emitting diodes (LEDs) has a depigmentation effect to the skin when applied before the UV irradiation in animal model. But it lacks whether irradiation of LED after the UV exposure has depigmentation effects. Objectives: To investigate the effects of 660-nm LED on inhibition of melanogenesis after the UV exposure in C57BL/6J mouse model Methods: After 1 week stabilization period, five-week-old male C57BL/6J melanin-possessing mice were randomly divided into four groups; control (N=9), UV only (280nm UV 300 mJ/㎠ irradiation) group (N=9), post-LED (660nm LED 20 J/㎠ irradiation 6 hours after 280nm UV 300 mJ/㎠) group (N=9), and pre-LED (660nm LED 20 J/㎠ irradiation 6 hours before 280nm UV 300 mJ/㎠) exposure group (N=9). The dorsal skin color of each mouse was measured using a spectrocolorimeter every day. After 7 days of irradiation, dorsal skin samples and ear samples were obtained to see the tissues. Results: Measured delta L* value by daily colorimeter greatly decreased in the UV only group, followed by pre-LED group, and post-LED group. The amount of melanin in ear tissues were significantly decreased in pre-LED group (0.62 %±0.27) than UV only group (0.77 %±0.13). Also, the activities of melanocytes in ear tissues were significantly decreased in pre-LED group (0.44 %±0.05) than UV only group (0.85 % ± 0.35). Conclusion: 660nm irradiation before the UV exposure has an effect on depigmentation in C57BL/6J mouse model.

Toll-like Receptor 2 is Dispensable for an Immediate-early Microglial Reaction to Two-photon Laser-induced Cortical Injury <i>In vivo</i>

Heera Yoon,Yong Ho Jang,Sang Jeong Kim,Sung Joong Lee,Sun Kwang Kim 대한생리학회-대한약리학회 2015 The Korean Journal of Physiology & Pharmacology Vol.19 No.5

Microglia, the resident macrophages in the central nervous system, can rapidly respond to patho-logical insults. Toll-like receptor 2 (TLR2) is a pattern recognition receptor that plays a fundamental role in pathogen recognition and activation of innate immunity. Although many previous studies have suggested that TLR2 contributes to microglial activation and subsequent pathogenesis following brain tissue injury, it is still unclear whether TLR2 has a role in microglia dynamics in the resting state or in immediate-early reaction to the injury <i>in vivo</i>. By using <i>in vivo</i> two-photon microscopy imaging and Cx3cr1<i>^GFP/+</i> mouse line, we first monitored the motility of microglial processes (i.e. the rate of extension and retraction) in the somatosensory cortex of living TLR2-KO and WT mice; Microglial pro-cesses in TLR2-KO mice show the similar motility to that of WT mice. We further found that microglia rapidly extend their processes to the site of local tissue injury induced by a two-photon laser ablation and that such microglial response to the brain injury was similar between WT and TLR2-KO mice. These results indicate that there are no differences in the behavior of microglial processes between TLR2-KO mice and WT mice when microglia is in the resting state or encounters local injury. Thus, TLR2 might not be essential for immediate-early microglial response to brain tissue injury <i>in vivo</i>.

Bicycle Repair Station

Heera Oh(오희라) 한국디자인학회 2015 한국디자인학회 국제초대전도록 Vol.2015 No.5

FC 2-7 : Effect of 660-nm light emitting diode (LED) on the skin pigmentation before and after the ultraviolet (UV) irradiation in C57BL/6J mouse model

( Heera Lee ),( Jee Woong Choi ),( You Chan Kim ) 대한피부과학회 2021 대한피부과학회 학술발표대회집 Vol.73 No.-

Background: It has been researched that light-emitting diodes (LEDs) has a depigmentation effect to the skin when applied before the UV irradiation in animal model. But it lacks whether irradiation of LED after the UV exposure has depigmentation effects. Objectives: To investigate the effects of 660-nm LED on inhibition of melanogenesis after the UV exposure in C57BL/6J mouse model Methods: After 1 week stabilization period, five-week-old male C57BL/6J melanin-possessing mice were randomly divided into four groups; control (N=9), UV only (280nm UV 300 mJ/㎠ irradiation) group (N=9), post-LED (660nm LED 20 J/㎠ irradiation 6 hours after 280nm UV 300 mJ/㎠) group (N=9), and pre-LED (660nm LED 20 J/㎠ irradiation 6 hours before 280nm UV 300 mJ/㎠) exposure group (N=9). The dorsal skin color of each mouse was measured using a spectrocolorimeter every day. After 7 days of irradiation, dorsal skin samples and ear samples were obtained to see the tissues. Results: Measured delta L* value by daily colorimeter greatly decreased in the UV only group, followed by pre-LED group, and post-LED group. The amount of melanin in ear tissues were significantly decreased in pre-LED group (0.62 %±0.27) than UV only group (0.77 %±0.13). Also, the activities of melanocytes in ear tissues were significantly decreased in pre-LED group (0.44 %±0.05) than UV only group (0.85 % ± 0.35). Conclusion: 660nm irradiation before the UV exposure has an effect on depigmentation in C57BL/6J mouse model.

Electrical and Optical Properties of Nickel Thin-films Fabricated by using Oblique-angle Deposition

Heera Kwon,Chel-Jong Choi,Jaehee Cho 한국물리학회 2016 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.68 No.7

When investigating nickel (Ni) thin films deposited by using an oblique angle deposition (OAD) technique, we find a strong correlation between the structural, electrical, and optical properties. The microstructure of the Ni thin-films is largely influenced by the deposition angle of the OAD technique. By increasing the deposition angle, we find that the sheet resistance of the Ni thin-films increases superlinearly and that the optical reflectance of the films increases. These results are explained by the degree of formation of a columnar nanostructure during OAD deposition.

Optimal Engine Operation by Shift Speed Control of a CVT

Heera Lee,Hyunsoo Kim 대한기계학회 2002 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.16 No.7

In this paper, an algorithm to increase the shift speed is suggested by increasing the line pressure for a metal belt CVT. In order to control the shift speed, an algorithm to calculate the target shift speed is presented from the modified CVT shift dynamics. In applying the shift speed control algorithm, a criterion is proposed to prevent the excessive hydraulic loss due to the increased line pressure. Simulations are performed based on the dynamic models of the hydraulic control valves, powertrain and the vehicle. It is found from the simulation results that performance of the engine operation can be improved by the faster shift speed, which results in the improved fuel economy by 2% compared with that of the conventional electronic control CVT in spite of the increased hydraulic loss due to the increased line pressure.<br/> <br/>

Alopecia areata is not a risk factor for heart diseases: A 10-year retrospective cohort study

( Heera Lee ),( You Chan Kim ),( Jee Woong Choi ) 대한피부과학회 2019 대한피부과학회 학술발표대회집 Vol.71 No.2

Background: Alopecia areata (AA) is an autoimmune skin disease caused by chronic inflammation of the hair follicles. Chronic inflammatory skin diseases, such as psoriasis and lupus erythematosus can increase the risk of cardiovascular diseases. However, the relationship between AA and heart diseases is unclear. Objectives: To evaluate the risk for subsequent heart diseases in patients with AA Methods: We conducted a retrospective cohort study using data of 3,770 cases of AA, and age-, sex-, and income level-matched 18,850 controls from the National Health Insurance Service-National Sample Cohort. In subgroup analysis, those who suffered from alopecia totalis, alopecia universalis, and ophiasis designated as severe AA, and who having had over a year of the disease defined as long-standing AA. Results: AA was not related to a higher risk of heart failure, angina pectoris, and myocardial infarction. There was no significant increase in the risk of overall heart diseases associated with AA (adjusted hazard ratio, 1.17; 95 % confidence interval, 0.93-1.48; p= 0.177). Neither severity nor duration of AA was related to the increased risk of heart diseases. During the study period, AA patients didn’t show a significantly higher cumulative incidence of heart diseases than controls (log-rank p=0.157). Conclusion: AA does not increase the risk of heart diseases.

A case of malignant melanoma in an infant

( Heera Lee ),( Sujin Park ),( Kee Yang Chung ),( You Chan Kim ) 대한피부과학회 2021 대한피부과학회 학술발표대회집 Vol.72 No.2

Malignant melanoma is a very rare disease in children. In contrast to the established diagnostic, therapeutic, and prognostic criteria for adult melanoma, the clinical features of pediatric melanoma are poorly characterized at present. Herein, we report an infant of malignant melanoma. A 13-month-old boy presented with irregular bordered, black-colored scaly plaque, sized about 1 cm on the lateral side of the left hand which had existed since birth. Skin biopsy from the lesion exhibited pigmented parakeratosis, pagetoid spreads of melanocytes in the epidermis, junctional mitotic activity, and pleomorphic melanocytes showing abnormal mitotic figures in upper dermis. Also, loss of p16 immunohistochemical stain made it possible to rule out Spitz nevus. Thus, the lesion was diagnosed with malignant melanoma. After that, image analysis was conducted to confirm the infiltrated depth range and presence of metastasis. In magnetic resonance imaging (MRI), there was no evidence of metastasis around the lesion. And in torso positron emission tomography/computed tomography (PET/CT) scan from forehead to mid-thigh, there was no significant fludeoxyglucose (FDG) uptake suggesting malignancy. Thus, under the diagnosis of malignant melanoma, the infant underwent Mohs micrographic surgery with rhomboid flap. So far, the infant showed no complication and recurrence for 8 months.

Multiple whitish papules on the trunk: a case series

( Heera Lee ),( You Chan Kim ),( Eun So Lee ) 대한피부과학회 2021 대한피부과학회 학술발표대회집 Vol.72 No.2