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.

Volatile Compounds as Markers of Tofu (Soybean Curd) Freshness during Storage

Lee, Seonmi,Cho, Heera,Lee, Kwang-Geun American Chemical Society 2014 Journal of agricultural and food chemistry Vol.62 No.3

<P>Volatile compounds in packed and unpacked commercial tofu were extracted by solid phase microextraction fibers and analyzed by gas chromatography–mass spectrometry. The tofu samples were stored at 4 °C for 15 days to measure freshness and quality changes during storage. Totals of 41 and 35 volatile compounds were identified from packed tofu and unpacked tofu, respectively. Peak area ratio (PAR) of hexanal in packed tofu increased from 11.44 (day 0) to 496.30 (day 9) and finally decreased to 11.06 on day 15 of storage. PAR of ethanol and 1-hexanol increased from 5.41 and 0.76 (day 1) to 66.93 (day 9) and 47.46 (day 15), respectively. Changes in these volatiles in unpacked tofu were similar to those in packed tofu. The results show that hexanal, ethanol, and 1-hexanol are characteristic volatile compounds for providing quantitative and qualitative information regarding deterioration of tofu.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/jafcau/2014/jafcau.2014.62.issue-3/jf404847g/production/images/medium/jf-2013-04847g_0007.gif'></P>

Shift Speed Improvement of a Metal Belt CVT

Lee, Heera,Kim, Hyunsoo The Korean Society of Mechanical Engineers 2001 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.15 No.12

This parer presents a CVT line pressure control strategy for the increased shift speed. Firstly, an algorithm to increase the CVT shift speed is suggested based on a modified CVT shift dynamics and shift speed maps are constructed. In addition, simplified dynamic models of the line pressure and the ratio control valve are derived by considering the CVT shift dynamics, and low level control algorithms for the ratio and the line pressure control are proposed. Using the shift speed maps and the simplified dynamic models of the CVT system, shift performance is investigated. It is found from the experimental and simulation results that improved shift speed can be achieved by increasing the lilly pressure.

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/>

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.

Optimal Engine Operation by Shift Speed Control of a CVT

Lee, Heera,Kim, Hyunsoo The Korean Society of Mechanical Engineers 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.

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.

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.

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

Lee, Heera,Kim, Hyunsoo The Korean Society of Mechanical Engineers 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.

Association between the first exposure to general anesthesia and alopecia areata

( Heera Lee ),( Young Woong Choi ),( You Chan Kim ),( Jee Woong Choi ) 대한피부과학회 2022 대한피부과학회 학술발표대회집 Vol.74 No.1