Comparison of Predicted Exercise Capacity Equations in Adult Korean Subjects

Jeong Daehyun,Oh Yeon-Mok,Lee Sei Won,Lee Sang-Do,Lee Jae Seung 대한의학회 2022 Journal of Korean medical science Vol.37 No.14

Background: Maximal oxygen uptake (VO2 max) is a useful index to assess exercise capacity. However, there is no reference value for Koreans. This study aimed to compare actual VO2 max and predicted VO2 max using exercise capacity equations in Korean subjects. Methods: This retrospective study enrolled 383 patients who underwent cardiopulmonary exercise test (CPET) with incremental maximal cycle ergometer test at Asan Medical Center from January 2020 to May 2021. Stage 1 and 2 lung cancer patients with normal lung function and healthy persons of 50 subjects who had maximal CPET were analyzed. Results: The subjects were aged 65 ± 13 years and predominantly male (74%). CPET results were as follows: absolute VO2 max, 1.2 ± 0.3 L/min; body weight referenced VO2 max, 20 ± 3.9 mL/kg/min; peak work rate, 94 ± 24 watts; peak heart rate, 142 ± 21 bpm; peak O2 pulse, 10 ± 3 mL/beat; minute ventilation, 59 ± 14 L/min; peak respiratory rate, 34 ± 6 breaths per minute; and peak breathing reserve, 41 ± 18%. There was significant discordance between the measured and predicted absolute VO2 max using the Jones, Hansen, and Wasserman prediction equations developed for Caucasian population (P < 0.001). Agreement using Bland-Altman test between true and predicted absolute VO2 max was the best in Chinese equation (−0.03, 2SD = 0.55) compared to Jones (0.42, 2SD = 1.07), Hansen (0.44, 2SD = 0.86), and Wasserman (0.42, 2SD = 0.86) equations. Conclusion: The reference value and prediction equation from studies including primarily Caucasians may not be appropriate for Koreans. Since the mean difference is the lowest in Chinese equation, the Chinese equation might be used for the Korean adult population.

25-Gb/s Clocked Pluggable Optics for High-Density Data Center Interconnections

Jeong, Gyu-Seob,Hwang, Jeongho,Choi, Hong-Seok,Do, Hyungrok,Koh, Daehyun,Yun, Daeyoung,Lee, Jinhyung,Park, Kwanseo,Ko, Han-Gon,Lee, Kwangho,Joo, Jiho,Kim, Gyungock,Jeong, Deog-Kyoon IEEE 2018 IEEE TRANSACTIONS ON CIRCUITS AND SYSTEMS PART 2 E Vol.65 No.10

<P>This brief presents a clocked pluggable optics suitable for high-density data center interconnections. The proposed architecture performs a SERDES function at the module side by exploiting a forwarded clock from the ASIC. Due to the relaxed channel loss of the ASIC-to-module interface, the use of power-hungry equalizers can be avoided. Based on an 850-nm multi-mode fiber interface, a 25-Gb/s link operation is demonstrated. A vertical-cavity surface-emitting laser-based transmitter outputs an optical modulation power of 0.6 mW. The optical receiver sensitivity is measured to be −7.5 dBm at 21.2 Gb/s with an optical excitation, and <TEX>$120~{\mu }\text{A}_{\text{pp}}$</TEX> at 25 Gb/s with an electrical excitation. The jitter tracking capability of the implemented clock and data recovery is evaluated in the presence of ±100-ppm frequency offsets and the measured jitter tolerance complies with the 100 GbE specification well. The optical transceiver is implemented in 65-nm CMOS technology and consumes 281 mW at 25 Gb/s, corresponding to the energy efficiency of 11.2 pJ/b.</P>

A 28 Gb/s Receiver Front-end Capable of Receiving Wide Range Current Signal in 65 nm CMOS

Daehyun Koh,Daniel Jeong,Jeongho Hwang,Deog-Kyoon Jeong 대한전자공학회 2022 Journal of semiconductor technology and science Vol.22 No.6

Comparison of Predicted Exercise Capacity Equations in Adults Korean Subjects

( Daehyun Jeong ),( Yeon-mok Oh ),( Sei Won Lee ),( Sang-do Lee ),( Jae Seung Lee ) 대한결핵 및 호흡기학회 2021 대한결핵 및 호흡기학회 추계학술대회 초록집 Vol.129 No.-

Background/Aims Maximal oxygen uptake (VO2 max) is useful index for assessment of exercise capacity. There is no reference value of VO2 max for Koreans. The purpose of this study is to compare actual VO2 max and predicted VO2 max using exercise capacity equations. Method This is a retrospective study using data for 383 patients who underwent cardiopulmonary exercise test (CPET) with incremental maximal cycle ergometer test at Asan medical center from January, 2020 to May, 2021. Among subject, stage 1, 2 lung cancer patients with no dyspnea and healthy persons with complaints of dyspnea of 131 subjects who had maximal CPET was analyzed. Results The study population aged 66±10 with male predominance (74%). CPET Results were VO2 max (L/min) of 1.25±0.32, VO2 max (ml/kg/min) of 19.6±3.6, peak work rate (watts) of 93.6±25.4, peak heart rate (bpm) of 146±20, peak O2 pulse (ml/beat) of 9.1±3, ventilator efficiency of 34±4.1, peak respiratory rate 34±7, and peak breathing reserve (%) of 35±18. There was significant discordance between the measured VO2 max and predicted VO2 max when predicted by the Jones, Hansen, and Wasserman prediction equations developed by Caucasian population (P < 0.001). Agreement using Bland-Altman test between True VO2 max and predicted VO2 max was the best in Chinese equation (-0.15, 2SD = 0.46) compared to Jones (0.43, 2SD = 0.98), Hansen (0.42, 2SD = 0.69), and Wasserman (0.42, 2SD = 0.69) equations Conclusions The reference value and prediction equation from studies in which populations were primarily Caucasian may not be appropriate for Koreans. Since the mean difference is the lowest in Chinese equation, it is considered appropriate to use Chinese equation in the Korean adult population.

CNT를 강화재로 사용한 경량구조용 고분자복합재료의 개발경향

정대현 ( Daehyun Jeong ),길상철 ( Sang Cheol Kil ),남수우 ( Soo Woo Nam ) 대한금속재료학회(구 대한금속학회) 2014 대한금속·재료학회지 Vol.52 No.11

Composite materials are artificially engineered materials composed of a matrix and filler with reinforcing agents embedded in the matrix to enhance various properties. These days, as the demand for lightweight and high performance composite materials is increasing, especially in the field of transportation, many efforts are focused on research activity in the area of carbon nanotube (CNT) composite materials. In this review paper, the first discovery of the CNT is considered and the various properties of CNTs, such as mechanical (stiffness, tensile strength, damping), electrical and thermal properties, are briefly explained. For the evaluation of the recent lightweight and high performance CNT composites research trends, papers published within the last 10 years are selected. The role of the strengthener CNTs (SWCNTs and MWCNTs) and several different polymers (epoxy resin, polypropylene and polystyrene) for the matrix materials are considered in the evaluation. It is found that many research activities for the modification of the CNT surface focus on the uniform distribution of the CNTs in the matrix. Research work for the improvement of the binding energy between CNTs and polymers is also emphasized to optimize the mechanical behaviors. (Received August 11, 2014)

Porphyromonas gingivalis에 대한 노각나무 잎 추출물의 항균활성 및 생물막 형성 억제 효과

김혜수(Hye Soo Kim),박민정(Min Jeong Park),김수정(Soo Jeong Kim),김부경(Bu Kyung Kim),박준호(JunHo Park),김대현(DaeHyun Kim),조수정(Soo Jeong Cho) 한국생명과학회 2021 생명과학회지 Vol.31 No.3

본 연구에서는 천연물유래 구강건강 개선소재로써 노각나무의 이용 가능성을 알아보기 위해 노각나무 잎과 줄기를 에탄올에 추출한 다음 구강미생물에 대한 추출물의 항균활성을 조사하였다. 노각나무 잎과 줄기 추출물(1 mg/disc)은 구강미생물 중 P. gingivalis KCTC5352에 대해서만 항균활성을 나타내었으며 줄기보다는 잎 추출물의 항균활성이 우수하였다. 시판되고 있는 구강케어제품에 사용되고 있는 항균제와 노각나무 잎 추출물의 항균활성을 비교한 결과, P. gingivalis에 대한 노각나무 잎 추출물과 양성대조구로 사용한 triclosan의 항균활성은 유사하게 나타났으며. P. gingivalis에 대한 노각나무 잎 추출물의 MIC는 0.4 mg/ml이고 정균작용을 하였다. 노각나무 잎 추출물이 0.2-2.0 mg/ml 농도로 처리된 배양액에서 P. gingivalis KCTC5352의 생물막 형성과 세균 생육은 추출물의 농도가 증가할수록 농도의존적으로 억제되는 경향을 보였다. 또한 노각나무 잎 추출물(1 mg/ml) 처리가 P. gingivalis의 생물막 형성에 미치는 영향을 주사전자현미경으로 관찰한 결과에 의하면 추출물을 처리하지 않은 대조구는 추출물 처리구에 비해 P. gingivalis가 군집을 이루며 모여 있었고 세포 주변에서 생물막이 관찰되었지만 추출물을 처리한 처리구의 세포 주변에서는 생물막을 관찰할 수 없었다. qRT-PCR을 이용하여 생물막 형성 초기 과정에서 치면 부착에 필수적인 섬모(fimbriae)관련 mRNA 발현 양상을 0조사한 결과, 노각나무 잎 추출물이 0.2-2.0 mg/ml의 농도로 처리된 배양액에서 fimA와 mfa1 유전자 발현은 추출물의 농도가 높아질수록 농도의존적으로 억제되는 것을 확인할 수 있었다. 이상의 결과를 종합하면 노각나무 잎 추출물은 치주질환 원인균인 P. gingivalis에 대한 항균 활성과 생물막 형성 억제능이 우수하기 때문에 천연물유래 구강건강 개선소재로써 이용 가능성이 높을 것으로 판단된다. This study was conducted to investigate the potential of Stewartia koreana as oral healthcare materials. The antibacterial activity of ethanol extracts from leaves and branches of S. koreana against oral bacteria was confirmed. The leaf and branch extracts (1 mg/disc) showed antibacterial activity against P. gingivalis only among several tested oral bacteria. The leaf extracts showed higher antibacterial activity, with values similar to those of chlorhexidine, which was used as a positive control. The MIC of the leaf extract against P. gingivalis was 0.4 mg/ml and showed bacteriostatic action. The inhibitory effects of the extract on biofilm formation and on gene expression related to biofilm formation by P. gingivalis were determined by biofilm biomass staining, scanning electron microscopy (SEM), and qRT-PCR analysis. The biofilm production rate and cell growth of P. gingivalis in the cultures treated with 0.2-2.0 mg/ml of S. koreana leaf extracts were significantly decreased in a concentration-dependent manner. The inhibitory effect on the formation of P. gingivalis biofilms at concentrations of 1 mg/ml was confirmed by SEM. The qRT-PCR analysis showed concentration-dependent suppression of the fimA and fimB gene expression associated with fimbriae formation in the cultures treated with 0.2-2.0 mg/ml S. koreana leaf extract. These results support the conclusion that S. koreana leaf extracts can be used as oral healthcare materials derived from natural materials, as demonstrated by the antibacterial action and inhibition of biofilm formation of P. gingivalis.

노각나무 잎과 가지 추출물의 항산화 효과

김혜수(Hye Soo Kim),박민정(Min Jeong Park),김수정(Soo Jeong Kim),김부경(Bu Kyung Kim),박준호(JunHo Park),김대현(DaeHyun Kim),조수정(Soo Jeong Cho) 한국생명과학회 2021 생명과학회지 Vol.31 No.2

본 연구에서는 우리나라 고유 수종인 노각나무(Stewartia koreana)의 부위별 이용 가능성을 알아보기 위하여 노각나무 잎과 가지를 70% 에탄올에 침지한 다음 부위별 항산화 활성을 조사하였다. 노각나무 가지 추출물(53.18±0.2 mg GAEs/extract g)에 비해 잎 추출물(162.57±0.9 mg GAEs/extract g)의 총 폴리페놀 함량이 높게 나타났고 플라보노이드 함량도 가지(4.7±0.1 mg QEs/extract g)에 비해 잎(59.1±0.9 mg QEs/extract g)에서 높게 나타났다. 노각나무 추출물의 DPPH 라디칼 소거능과 ABTS 라디칼 소거 활성은 잎과 가지 모두 농도 의존적으로 증가하였으며 가지보다는 잎에서 높게 나타났다. 노각나무 추출물 0.4 mg/ml의 농도에서 잎과 가지의 DPPH 라디칼 소거능은 각각 91.85±0.01%, 29.93±0.2%였으며 노각나무 잎 추출물은 양성대조구로 사용한 ascorbic acid (1mg/ml, 93.71±0.1%) 보다 낮은 농도에서 ascorbic acid와 유사한 DPPH 라디칼 소거능을 나타내었다. 노각나무추출물 0.4 mg/ml의 농도에서 잎과 가지의 ABTS 라디칼 소거능은 각각 94.77±0.34%, 25.13±0.15%였다. 노각나무잎과 가지의 ORAC 지수는 각각 104.13±0.48 μM TEs/ extract g과 57.36±0.35 μM TEs/extract g으로 가지보다는 잎의 ORAC 지수가 더 높게 나타났다. 노각나무 추출물의 세포 독성은 WST-1 assay를 이용하여 추출물이 섬유아세포 CCD-986sk에 미치는 영향으로 평가하였다. 이상의 결과를 종합해보면, 노각나무 잎 추출물은 가지에 비해 항산화 활성 지표인 총 폴리페놀과 플라보노이드 함량이 높고 항산화 활성이 높기 때문에 노각나무 잎 추출물은 항산화 활성이 우수한 기능성 식의약품소재나 화장품 소재로 사용될 수 있을 것으로 판단된다. This study was carried out to evaluate the antioxidant properties of the dried leaves and branches of Stewartia koreana Nakai. The dried leaf and branch of S. koreana were extracted with 70% ethanol at 80℃. The antioxidant activities of ethanol extracts of S. koreana leaf (EESL) and S. koreana branch (EESB) were analyzed. The total polyphenol contents in EESL and EESB were 162.57±0.9 mg of GAEs/extract g and 59.1±0.9 mg of GAEs/extract g, respectively. The flavonoid contents in EESL and EESB were 59.1±0.9 mg of QEs/extract g and 4.7±0.1 mg of QEs/extract g, respectively. EESL showed a better scavenging ability with DPPH and ABTS than EESB, at 0.4 mg/ml. Moreover, EESL were more effective according to ORAC values than EESL. The toxicity of EESL was investigated using a WST-1 assay on the human skin fibroblast cell line CCD-986sk. Therefore, EESL can be used as a potential source of functional, naturally-sourced material in cosmetics as well as food.

25Gbps Wireline Inverter-based Shunt Feedback Optical Receiver Front-end

Daehyun Koh,Deog-Kyoon Jeong 대한전자공학회 2019 대한전자공학회 학술대회 Vol.2019 No.6

Deep learning for tropical cyclone intensity change prediction

Jeong-Hwan Kim,Yoo-Geun Ham,Daehyun Kim,Tim Li 한국기상학회 2022 한국기상학회 학술대회 논문집 Vol.2022 No.10

Comparison between univariate and multivariate data assimilation of satellite Arctic sea ice concentration and thickness data

Jeong-Gil Lee,Yoo-Geun Ham,Daehyun Kang 한국기상학회 2023 한국기상학회 학술대회 논문집 Vol.2023 No.10