A comparison of imputation methods using machine learning models

Heajung Suh,Jongwoo Song The Korean Statistical Society 2023 Communications for statistical applications and me Vol.30 No.3

Handling missing values in data analysis is essential in constructing a good prediction model. The easiest way to handle missing values is to use complete case data, but this can lead to information loss within the data and invalid conclusions in data analysis. Imputation is a technique that replaces missing data with alternative values obtained from information in a dataset. Conventional imputation methods include K-nearest-neighbor imputation and multiple imputations. Recent methods include missForest, missRanger, and mixgb ,all which use machine learning algorithms. This paper compares the imputation techniques for datasets with mixed datatypes in various situations, such as data size, missing ratios, and missing mechanisms. To evaluate the performance of each method in mixed datasets, we propose a new imputation performance measure (IPM) that is a unified measurement applicable to numerical and categorical variables. We believe this metric can help find the best imputation method. Finally, we summarize the comparison results with imputation performances and computational times.

캡사이신 첨가 고지방식이가 운동시 조직 글리코겐 농도에 미치는 영향

서혜정(Suh Heajung),임기원(Lim Kiwon) 韓國營養學會 2001 Journal of Nutrition and Health Vol.34 No.7

5주간의 고지방식이 섭취시 흰쥐의 에너지 대사 기질 이용과 식이지방에너지 평가에 관한 연구

황혜정(Hyejung Hwang),김지수(Jisu Kim),서혜정(Heajung Suh),임기원(Kiwon Lim) 한국식품영양과학회 2012 한국식품영양과학회지 Vol.41 No.8

This study investigated the effect of a long-term high-fat diet on energy metabolic substrate utilization in resting rats in order to revalue source fat energy efficiency during a high-fat diet and its effect on energy expenditure and body fat accumulation. Sprague-Dawley male rats at 4 weeks of age were bought from Orient Bio Con. The rats were divided into a control (CON) group and a high-fat diet (HF) group. Rats ate a high-fat diet (w/w 40%, kcal/kcal 64.9%) ad libitum for 5 weeks. Food intake and body weight were measured every day at 09:00 throughout the experimental period. Energy expenditure was measured using an animal energy metabolism chamber after 4 weeks. The final body weight did not change between the CON and HF groups, but caloric intake was significantly higher in the HF group than in the CON group (p<0.05). There was no difference between the groups in oxygen uptake, however carbon dioxide production was significantly higher in the HF group. Also, the respiratory exchange ratio was higher in the HF group. Carbohydrate oxidation was lower in the HF group than in the CON group, but fat oxidation in the HF group was greater. These results mean that energy substrate oxidation at rest is affected by diet composition, especially dietary fat content. Abdominal fat fad weights were significantly higher by 33% in the HF group than in the CON group even though the calorie intake in the HF group was higher by 6%. These results suggested that the dietary fat calorie value might have a higher Atwater value of 9 kcal/g, which mean that dietary fat calorie values could be reconsidered in body weight control scenarios such as which the obese or weight class athletes.

Effects of Konan red ginseng intake during endurance training on resting energy metabolism in male mice

( Hye Jung Hwang ),( Ji Su Kim ),( Bokyung Kim ),( Chi Ho Lee ),( Heajung Suh ),( Heayeon Yun ),( Jonghoon Paik ),( Kiwon Lim ) 한국운동영양학회 2013 Physical Activity and Nutrition (Phys Act Nutr) Vol.17 No.1

This study was designed to investigate the effect of red ginseng (RG) intake during 2 weeks of training on the resting energy metabolism in mice. RG (20 mg/kg body weight) were orally administered to 7-week old male ICR mice during 2 weeks of endurance training. The resting metabolic rate for 24h was measured before and after the 2 week experimental periods. The total amount of food intake was significantly higher in the RG group than in the control group (p < 0.05), whereas mean body weight was not different. Oxygen uptake during 24 hours both before and after the experimental session was not different between the two groups. Carbohydrate oxidation and fat oxidation in resting were significantly decreased and increased by endurance training, respectively, but no difference was observed between the two groups. Accordingly. we suggest that red ginseng intake of 20mg/kg body weight during 2 weeks of endurance training may not affect resting energy metabolism (RER) over one day in male mice.

Effects of Different doses of Silk Peptide on Energy Metabolism During Exercise in Mice

( Jisu Kim ),( Jonghoon Park ),( Bokyung Kim ),( Chi-ho Lee ),( Kiwon Lim ),( Heajung Suh ) 한국운동영양학회 2017 Physical Activity and Nutrition (Phys Act Nutr) Vol.21 No.1

[Purpose] This study was carried out to determine the optimal dose of silk peptide for enhancing fat metabolism during exercise. [Methods] Fifty male ICR mice were randomly divided into five groups: Sed, SP0, SP200, SP400, and SP800. All SP mice underwent training by running on a treadmill 5 times a week for 2 weeks (20 m/min, 8° slope, 50 min/day for the first week and 25 m/min, 8° slope, 50 min/day at about 70-75% of maximum oxygen uptake for the second week). [Results] After the 2 weeks, fat oxidation was measured during a 1-h exercise at the training conditions of the second week and was found to be 1.02 ± 0.15, 1.04 ± 0.17, 0.98 ± 0.10, 1.14 ± 0.19, and 1.15 ± 0.07 g/kg/ h for Sed, SP0, SP200, SP400, and SP800 groups, respectively. The SP800 group had significantly higher fat oxidation levels than the SP0 group did at 36, 40, and 56 min and the Sed group did at 2, 4, 6, 8, 12, 14, 16, 20, 40, 46, 50, 52, 56, and 60 min. However, there was no significant difference among the groups in carbohydrate oxidation during the 1-h exercise. SP doses of 200 mg/kg and 400 mg/kg did not show any effect on fat and carbohydrate oxidation. [Conclusion] In conclusion, 800 mg/kg of silk peptide is the optimal dose for enhancing fat metabolism during exercise. In addition, silk peptide treatment could reduce body weight by enhancing fat metabolism.

Silk peptide intake increases fat oxidation at rest in exercised mice.

Kim, Jisu,Hwang, Hyejung,Yun, Hea-Yeon,Kim, Bokyung,Lee, Chi-Ho,Suh, Heajung,Lim, Kiwon Center for Academic Pub., Japan [etc.] 2013 JOURNAL OF NUTRITIONAL SCIENCE AND VITAMINOLOGY Vol.59 No.3

<P>Silk peptides (SP) have been reported to decrease body weight and accumulate fat. We investigated the effects of SP administration by using an open circuit calorimetry system on resting energy expenditure and substrate utilization in resting mice for the duration of 24 h. Seven-week-old male ICR-mice were orally administered SP (800 mg/kg) for 2 wk and were subjected to endurance training. The results indicated that not only was oxygen uptake higher in the SP group than in the CON group (*p<0.05), but also the respiratory exchange rate was lower than that in the CON group for the duration of 24 h (**p<0.01). Moreover, fat oxidation was increased in the SP group. Body weight of the SP group was significantly decreased compared to that of the CON group (*p<0.05). These results suggest that intake of silk peptides increases fat oxidation during rest in exercised mice. Intake of silk peptides is considered to be a favorable supplement for athletes in training. In particular, it would be an effective supplement for athletes who require weight loss along with an increase in muscle mass.</P>

Effects of Silk Peptides Administration on Fat Utilization Over a Whole Day in Mice

( Jisu Kim ),( Jonghoon Park ),( Bokyung Kim ),( Chi-ho Lee ),( Kiwon Lim ),( Heajung Suh ) 한국운동영양학회 2016 Physical Activity and Nutrition (Phys Act Nutr) Vol.20 No.4

[Purpose] The aim of the present study was to investigate the effects of treatment with silk peptides (SP) on resting energy expenditure over a 24-h period and clarify the molecular mechanism underlying its enhancement of fat utilization in mouse skeletal muscles. [Methods] Sixteen male ICR mice (6-week-old) were divided into two groups and treated with distilled water and SP (CON and SP treatment groups, respectively). SP were dissolved in distilled water and administered to the SP group at 800 mg/kg while the CON group was administered distilled water orally daily for 2 weeks. Resting metabolic rate (RMR) was measured before and after SP ingestion for 2 weeks using an open circuit calorimetry system. After the treatments, we collected blood and skeletal muscle samples from the mice. [Results] Final body weight and body weight gain showed no significant difference in the CON and SP groups. Conversely, food intake was significantly lower in the SP group than it was in the CON group. The comparison of the respiratory exchange rate (RER) at various time points after the 2-week treatment revealed that it was significantly lower in the SP group than it was in the CON group at 9, 15, 16, and 18-22 h (Figure 3 B). The sum of the RER over 24-h was lower in the SP group than it was in the CON group, but the difference was not statistically significant. The protein levels of fatty acid translocase (FAT)/ cluster of differentiation 36 (CD36) were approximately 12% higher in the SP group than they were in the CON group but that of carnitine palmitoyltransferase I (CPTl) was not significantly different between the two groups. [Conclusion] These results suggest that treatment with SP 800 mg/kg for 2 weeks may promote fat utilization during physical activity, but not the entire day. In addition, SP treatment effectively enhanced FAT/CD36 protein level in skeletal muscle. In future investigations, it would be necessary to elucidate the effects of long-term SP intake on the resting metabolism of both animals and humans.