Effect of Underwater Gait Training with a Progressive Increase in Speed on Balance, Gait, and Endurance in Stroke Patients

( Heejoong Kim ),( Yijung Chung ) 대한물리치료학회 2019 대한물리치료학회지 Vol.31 No.4

Purpose: This study aimed to investigate the effect of progressive speed increase during underwater gait training on stroke patients’ balance, gait, and endurance, as well as to compare the effects of underwater gait training and land gait training. Methods: Subjects were randomly allocated into three groups. Underwater gait training group (n=10), land gait training group (n=9) and control group (n=9). The groups performed their respective programs as well as conventional physical therapy 3 times/week for 8 weeks. The patients were assessed before and after the experiment in terms of the Berg balance scale, characteristics of gait, and 6-minute walking test. Results: The beneficial effect perceived in the speed increase underwater gait training (UGT) group was significantly greater than in the groups who were trained with speed increase land gait training (LGT) group, and the control group regarding the following aspects: the Berg balance scale, the affected step length, the affected stride length, and the 6-minute walking test (p<0.05). The LGT group showed a more significant effect on the Berg balance scale, the affected step length, the affected stride length, and the 6-minute walking test (p<0.05), compared to the control group. Furthermore, the UGT group showed a significantly greater effect on the gait speed when compared to the control groupb (p<0.05). Conclusion: This study shows that progressive UGT is effective in improving balance, gait, and endurance in stroke patients. Therefore, we believe that progressive UGT may be used as a method for general physical therapy in patients with stroke.

Comparison of characteristics during backward walking according to various stride frequencies in underwater and ground environments

( Heejoong Kim ),( Yijung Chung ) 물리치료재활과학회 2018 Physical therapy rehabilitation science Vol.7 No.2

Objective: The purpose of this study was to investigate the relationship between heart rate (HR), self-awareness of exercise intensity (rating of perceived exertion, RPE), and 5-meter walk test (5MWT) of persons affected by stroke during backward walking according to the preferred stride frequency (PSF), PSF+3 and PSF+6 conditions. Design: Cross-sectional study. Methods: A total of 11 persons with stroke (9 males, 2 females) participated voluntarily. All patients underwent backward walking under the PSF, PSF+3, and PSF+6 conditions in underwater and ground environments, and each condition was performed for 5 minutes. The HR, RPE, and walking speeds were measured during walking, and the measured values from underwater and ground environments were compared. Results: The HR and RPE in the ground environment were significantly increased (p<0.05), and although the 5MWT showed an increase in speed, it was not significant. The HR and RPE in the underwater environment were also significantly increased (p<0.05), however, although the 5MWT results was increased, it was not significant. The HR and RPE were significantly increased in the PSF+6 condition (p<0.05). Conclusions: The results of this study showed that backward gait training underwater can provide an appropriate exercise intensity for stroke survivors and suggests that exercises performed in an underwater environment is more effective compared to the ground environment.

Current status and future of fisheries resources assessment in Korea

Heejoong Kang,Heewon Park,JI-Hoon Choi,Sang-Chul Yoon 한국수산과학회 양식분과 2021 한국수산과학회 양식분과 학술대회 Vol.2021 No.4

Effect of Underwater Gait Training with a Progressive Increase in Speed on Balance, Gait, and Endurance in Stroke Patients

Kim, Heejoong,Chung, Yijung The Korean Society of Physical Therapy 2019 대한물리치료학회지 Vol.31 No.4

Purpose: This study aimed to investigate the effect of progressive speed increase during underwater gait training on stroke patients' balance, gait, and endurance, as well as to compare the effects of underwater gait training and land gait training. Methods: Subjects were randomly allocated into three groups. Underwater gait training group (n=10), land gait training group (n=9) and control group (n=9). The groups performed their respective programs as well as conventional physical therapy 3 times/week for 8 weeks. The patients were assessed before and after the experiment in terms of the Berg balance scale, characteristics of gait, and 6-minute walking test. Results: The beneficial effect perceived in the speed increase underwater gait training (UGT) group was significantly greater than in the groups who were trained with speed increase land gait training (LGT) group, and the control group regarding the following aspects: the Berg balance scale, the affected step length, the affected stride length, and the 6-minute walking test (p<0.05). The LGT group showed a more significant effect on the Berg balance scale, the affected step length, the affected stride length, and the 6-minute walking test (p<0.05), compared to the control group. Furthermore, the UGT group showed a significantly greater effect on the gait speed when compared to the control groupb (p<0.05). Conclusion: This study shows that progressive UGT is effective in improving balance, gait, and endurance in stroke patients. Therefore, we believe that progressive UGT may be used as a method for general physical therapy in patients with stroke.

한국 서해 참조기(Larimichthys polyactis)의 육안판별법과 GSI판별법에 의한 성숙체장 추정

강희중 ( Heejoong Kang ),마지영 ( Ji Young Ma ),김현지 ( Hyeon Ji Kim ),김한주 ( Han Ju Kim ) 한국수산과학회(구 한국수산학회) 2020 한국수산과학회지 Vol.53 No.1

Determination of the precise size at sexual maturity is very important for science-based stock assessment and fisheries resource management. In this study, two different models, (1) a visual method and (2) a gonadosomatic index (GSI) method, were employed to estimate length at sexual maturity of the small yellow croaker Larimichthys polyactis in the Yellow Sea of Korea. The visual method is a common qualitative method using visual gonadal identification. Conversely, the GSI method is a quantitative method using the GSI, which can be easily and precisely collected. We compared results from these methods to determine the best approach, and to examine the practicality of the GSI method. Logistic regression of the maturity ogive was conducted using a general linear model (GLM) with the R statistics program. Also, the bootstrapped 95% confidence intervals of all estimates were calculated. The best-fit model was the visual method (R_Mc ² =0.805, AUC=0.989, L₅₀=15.1). Among models using the GSI method, the model computing GSIref=0.94 was the best-fit model (R_Mc ² =0.792, AUC=0.989, L₅₀=15.2). There was no significant difference between the two models, evidencing the effectiveness and accuracy of the GSI method.

On methanol to hydrocarbons reactions in a hierarchically structured ZSM-5 zeolite catalyst

Kim, Heejoong,Jang, Hoi-Gu,Jang, Eunhee,Park, Sung Jun,Lee, Taehee,Jeong, Yanghwan,Baik, Hionsuck,Cho, Sung June,Choi, Jungkyu Elsevier Science Publishers 2018 Catalysis today Vol.303 No.-

<P><B>Abstract</B></P> <P>Two type ZSM-5 catalysts (Si/Al ratio of ∼30) with different mesoporosity were synthesized by using a structure directing agent of tetra-<I>n</I>-butylphosphonium hydroxide. In particular, the molar compositions of ethanol and water in the synthetic precursor were changed in order to acquire the two type ZSM-5 catalysts. The resulting ZSM-5 catalysts were formed via the interconnection of very thin pillars or lamellae; (1) ∼6nm thick with marked mesoporosity (H_30; high mesoporous ZSM-5) and (2) ∼13nm thick without any considerable mesoporosity (L_30; low mesoporous ZSM-5). The pyridine-based acid titration reveals that H_30 had internal Brønsted acid sites similar to those in the commercially available ZSM-5 with a Si/Al ratio of 75 (referred to as C_75), though H_30 contained a large amount of external Brønsted acid sites. The methanol to hydrocarbons (MTH) reaction performance of these two ZSM-5 catalysts demonstrates that H_30 preferred to produce propene over ethene compared to C_75, while L_30 showed a very poor MTH performance mainly due to the lower amount of internal Brønsted acid sites. More desirably, a very short diffusional length (∼18,600 times lower than that in C_75) in H_30 considerably disfavored the aromatic dealkylation that is known to produce ethene. With this, H_30 allowed for achieving the ratio of propene to ethene as high as ∼9.1, which is, to the best of our knowledge, a highest value among the MTH results on ZSM-5 catalysts without any co-feed. Furthermore, ceria-doped H_30 not only enhanced the stability for the MTH reaction via a passivation of the external Brønsted acid sites, but also improved a propene to ethene ratio up to ∼15.0.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Hierarchically structured ZSM-5 catalysts were synthesized via self-pillaring. </LI> <LI> Mesopores in the range of 2–10nm were formed due to the space among the pillars. </LI> <LI> The self-pillared ZSM-5 was used for methanol to hydrocarbons (MTH) reactions. </LI> <LI> Reduced diffusion length in a catalyst allowed for a selective production of propene. </LI> <LI> The propene/ethene ratio as high as 9.1 from the MTH reaction was achieved. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

군집을 이루는 유연한 구조물 사이 간격이 유동에 미치는 영향에 관한 연구

성희중(Heejoong Seong),이현진(Hyeonjin Lee),박한욱(Hanwook Park) 대한기계학회 2022 대한기계학회 춘추학술대회 Vol.2022 No.11

It is important to remove microplastics because the environmental pollution caused by microplastics has been becoming serious. The flow characteristics between tandem flexible structures made of Polydimethylsiloxane(PDMS) are experimentally investigated to remove microplastics. Tandem flexible structures are motivated by respiratory cilia. To verify the effect of the gap distance on the movement of tandem flexible structures and flow behaviors in the channel, various gap distance models were fabricated. Gap flow and bending angle of tandem flexible structures are analyzed using flow visualization and Particle Image Velocimetry(PIV) techniques. When gap distance is moderate, a single recirculation flow was formed between tandem flexible structures and reattachment region was formed near the upper position of the rear flexible structure. Moreover, because the second recirculation zone was observed at the lower position of front flexible structure, this moderate gap distance is prepared to remove microplastics under present flow condition.

Comparison of characteristics during backward walking according to various stride frequencies in underwater and ground environments

Kim, Heejoong,Chung, Yijung korean Academy of Physical Therapy Rehabilitation 2018 Physical therapy rehabilitation science Vol.7 No.2

Objective: The purpose of this study was to investigate the relationship between heart rate (HR), self-awareness of exercise intensity (rating of perceived exertion, RPE), and 5-meter walk test (5MWT) of persons affected by stroke during backward walking according to the preferred stride frequency (PSF), PSF+3 and PSF+6 conditions. Design: Cross-sectional study. Methods: A total of 11 persons with stroke (9 males, 2 females) participated voluntarily. All patients underwent backward walking under the PSF, PSF+3, and PSF+6 conditions in underwater and ground environments, and each condition was performed for 5 minutes. The HR, RPE, and walking speeds were measured during walking, and the measured values from underwater and ground environments were compared. Results: The HR and RPE in the ground environment were significantly increased (p<0.05), and although the 5MWT showed an increase in speed, it was not significant. The HR and RPE in the underwater environment were also significantly increased (p<0.05), however, although the 5MWT results was increased, it was not significant. The HR and RPE were significantly increased in the PSF+6 condition (p<0.05). Conclusions: The results of this study showed that backward gait training underwater can provide an appropriate exercise intensity for stroke survivors and suggests that exercises performed in an underwater environment is more effective compared to the ground environment.

Effects of System Reliability Improvements on Future Risks

Yang, Heejoong The Korean Society for Quality Management 1996 품질경영학회지 Vol.24 No.1

In order to build a model to predict accidents in a complicated man-machine sytem, human errors and mechanical reliability can be viewed as the most important factors. Such factors are explicitly included in a generic model. Another point to keep in mind is that the model should be constructed so that the data in a type of accident can be utilized to predict other types of accidents. Based on such a generic prediction model, we analyze the effects of system reliability. When we improve the system reliability, in other words, when there are changes in model parameters, the predicted time to next accidents should be modified influencing the effects of system reliability improvements. We apply Bayesian approach and finds the formula to explain how a change on the machine reliability or human error probability influences the time to next accident.

군집을 이루는 유연한 구조물 사이 간격이 유동에 미치는 영향에 관한 연구

성희중(Heejoong Seong),이현진(Hyeonjin Lee),박한욱(Hanwook Park) 대한기계학회 2022 대한기계학회 춘추학술대회 Vol.2022 No.11

It is important to remove microplastics because the environmental pollution caused by microplastics has been becoming serious. The flow characteristics between tandem flexible structures made of Polydimethylsiloxane(PDMS) are experimentally investigated to remove microplastics. Tandem flexible structures are motivated by respiratory cilia. To verify the effect of the gap distance on the movement of tandem flexible structures and flow behaviors in the channel, various gap distance models were fabricated. Gap flow and bending angle of tandem flexible structures are analyzed using flow visualization and Particle Image Velocimetry(PIV) techniques. When gap distance is moderate, a single recirculation flow was formed between tandem flexible structures and reattachment region was formed near the upper position of the rear flexible structure. Moreover, because the second recirculation zone was observed at the lower position of front flexible structure, this moderate gap distance is prepared to remove microplastics under present flow condition.