Acoustically excited oscillating bubble on a flexible structure and its energy-harvesting capability

Jinpyo Jeon,홍지우,Sang Joon Lee,Sang Kug Chung 한국정밀공학회 2019 International Journal of Precision Engineering and Vol.6 No.3

When a bubble oscillates under the action of an acoustic field, it generates a cavitational microstreaming flow around it. We here explore oscillation dynamics of a bubble hanging on a flexible structure (i.e., piezocantilever) by acoustic excitation, and assess the suitability of the proposed method to micro-energy harvesting systems. We preferentially investigate the characteristics of bubble oscillation, such as the maximum amplitude and resonant frequency by varying the applied frequency and bubble size. The amplitude of the oscillating bubble is found to be maximized at the resonant frequency depending on the bubble size. Additionally, we measured the electrical outcome generated from bubble oscillation-induced microstreaming and resultant vibration of the piezocantilever, as functions of the applied frequency, bubble size, and distance between the bubble and piezoactuator. The generated voltage is considerably dependent of the applied frequency and bubble size. Meanwhile, it is inversely proportional to the distance between the bubble and piezoactuator. Finally, we found that the electrical output can be can be improved by increasing the number of bubbles. This work will provide a new framework for the fundamental design of bubble-mediated micro-energy harvesters and microsensors.

Magnetic Liquid Metal Marble: Characterization of Lyophobicity and Magnetic Manipulation for Switching Applications

Jeon, Jinpyo,Lee, Jeong-Bong,Chung, Sang Kug,Kim, Daeyoung IEEE 2016 Journal of microelectromechanical systems Vol.25 No.6

<P>We report a 'magnetic liquid metal marble' (MLMM) obtained by coating a liquid metal's surface with micro/nano-sized ferromagnetic iron (Fe) particles, which enables on-demand, magnetic manipulation of a liquid metal droplet for switching applications. Among liquidmetals, gallium-based liquid metal alloys have been developed for a variety of applications. However, most developed applications using the gallium-based liquid metal alloy only work on deformability because of its easywetting property stemming from surface oxidation. By coating the oxidized surface with the 45 mu m or 45 nm diameter Fe particles, the MLMM exhibits non-wetting property investigated by evaluating apparent contact angles and sliding angles against various surfaces. On the Teflon-coated glass, the largest contact angle was measured to be similar to 169.0 degrees, and the lowest sliding angle was obtained to be 17.2 degrees, respectively. In order to move the 45-mu m diameter Fe particles-coated MLMM, we measured the minimum required magnetic flux density of 150 gauss and demonstrated the magnetic control of the liquid metal marble to turn ON light emitting diodes. In addition, we investigated that hydrochloric acid-vapor treatment on the MLMM enhanced the lyophobicity (sliding angle of 9.4 degrees), reduced the minimum magnetic flux density (150 to 107 gauss) to actuate it, and enabled electrical switching applicability even in silicon oil with shorter delay time and high mobility of the MLMM under the applied magnetic field. [2016-0329]</P>

남북산림협력에 대한 국민적 인식에 관한 연구

전진표 ( Jinpyo Jeon ),서영완 ( Yeongwan Seo ),최인화 ( Inhwa Choi ),최정기 ( Jungkee Choi ) 한국산림경제학회 2022 산림경제연구 Vol.29 No.2

본 논문은 남북산림협력이 분단된 한반도의 평화협력에 기여하기 위한 기초자료를 제공하기 위하여 우리나라 국민의 남북산림협력에 대한 인식을 분석하였다. 분석 결과 응답자의 70.1%가 우리나라의 산림녹화사업이 세계적인 성공사례로 인식하고 있으며, 산림녹화사업이 성공한 가장 큰 요인은 ‘국가역량의 총동원’ 때문이라고 답하였다. 북한의 산림황폐는 ‘한반도의 기상이변의 초래’ 또는 ‘한반도의 산림생태계교란’에 가장 영향을 미치며, ‘산림녹화물자의 지원’이 북한의 산림녹화를 도울 수 있는 가장 효과적인 방법으로 인식하였다. 또한, 남북의 산림분야 교류협력이 지속적으로 추진되어야 하고, 정부 기구 중 산림청이 산림교류 협력을 주도해야 하며, ‘북한의 군사적 위협 해소와 정부 차원의 협력사업 추진’이 남북 산림교류 협력의 발전에 가장 중요한 요소인 것으로 나타났다. 마지막으로 북한에 대한 가장 인도주의적 지원 분야 및 방법은 ‘산림황폐지의 복구’와 ‘식량의 지원’이며, 남북 긴장 완화와 평화적 관계의 발전을 위해 가장 중요한 것은 ‘북한의 핵무기 개발 중단’과 ‘남북 정부간 교류 재개’로 나타났다. This study analyzed the Korean people’s perception of inter-Korean forest cooperation projects to provide basic data for contributing to peace cooperation on the divided Korean Peninsula. The result showed that 70.1% of the respondents recognized Korea’s forest greening project as a worldwide successful case, and the most important factor in the success of the forest greening project was due to ‘total mobilization of national capabilities.’ North Korea’s deforestation had the greatest impact on ‘causing extreme weather on the Korean Peninsula’ or ‘disrupting the forest ecosystem on the Korean Peninsula’, and it was recognized that ‘support of foresters’ was the most effective way to help North Korea’s reforestation. In addition, it appeared that inter-Korean forest exchange cooperation should be continuously promoted, the Korea Forest Service had to lead forest exchange cooperation among government organizations and ‘resolving military threats from North Korea and promoting government-level cooperation’ were the most important factor in the development of inter-Korean forest exchange cooperation. Finally, South Korea’s most humanitarian aids to North Korea were ‘restoration of deforestation’ and ‘food aid,’ and the most important factor for easing inter-Korean tensions and developing peaceful relations were ‘the cessation of North Korea’s nuclear weapons development’ and ‘the resumption of exchanges between the South and the North.’

음파에 의해 구동되는 액체 금속 액적을 이용한 에너지 수확 시스템

전진표(Jinpyo Jeon),정상국(Sang Kug Chung),김대영(Daeyoung Kim) 한국가시화정보학회 2016 한국가시화정보학회 학술발표대회 논문집 Vol.2016 No.4

Childhood Exposure to Psychological Trauma and the Risk of Suicide Attempts: The Modulating Effect of Psychiatric Disorders

Subin Park,JinPyo Hong,HongJin Jeon,Sujeong Seong,MaengJe Cho 대한신경정신의학회 2015 PSYCHIATRY INVESTIGATION Vol.12 No.2

Objective-We examined whether childhood exposure to psychological trauma is associated with greater suicidality and whether specific psychiatric disorders modulate this association in a representative sample of Korean adults. Methods-The Korean version of the Composite International Diagnostic Interview 2.1 was administered to 6,027 subjects aged 18–74 years. Subjects who experienced a traumatic event before the age of 18 years, the childhood-trauma-exposure group, were compared with controls without childhood trauma exposure. Results-Childhood exposure to psychological trauma was associated with lifetime suicidal ideation (OR=3.19, 95% CI=2.42–4.20), suicide plans (OR=4.15, 95% CI=2.68–6.43), and suicide attempts (OR=4.52, 95% CI=2.97–6.88). These associations weakened after further adjustment for any psychiatric disorders, but they were not eliminated. The risk of suicide attempts related to childhood trauma increased with the presence of a concurrent alcohol use, depressive, or eating disorder. Conclusion-In terms of clinical implications, patients with these disorders who have a history of childhood trauma should be carefully assessed for their suicide risk and aggressively treated for psychiatric disorders.

Acoustic bubble-powered miniature rotor for wireless energy harvesting in a liquid medium

Jang, Deasung,Jeon, Jinpyo,Chung, Sang Kug Elsevier 2018 Sensors and actuators. A Physical Vol.276 No.-

<P><B>Abstract</B></P> <P>This paper presents a new type of acoustic energy harvesting technology in which a miniature rotor actuated by acoustically oscillating bubble-induced synthetic jets periodically vibrates piezocantilevers in order to generate electric power. The behavior of an oscillating bubble under acoustic excitation and an oscillating bubble-induced synthetic jet is experimentally verified to prove the working principle of an acoustically driven miniature rotor. The motion of the acoustically driven miniature rotor and the generated electric voltage from the vibrating piezocantilever are investigated. The rotating speed of the rotor and the electric voltage generated are highly dependent on the applied acoustic frequency. A custom-made electrical circuit with different electric loads is used to rectify the electric voltage and power generated by the vibrating piezocantilever. As proof of concept, storage capacitor charging tests are conducted with 0.1 μF and 1 μF capacitors. Furthermore, the effect of multiple piezocantilevers on the electric energy density is investigated to demonstrate the possibility of improving the electric energy density obtained from the proposed energy harvesting technology. The investigation shows that the total value of the voltage generated from piezocantilevers is proportional to the number of piezocantilevers.</P> <P><B>Highlights</B></P> <P> <UL> <LI> The behavior of an oscillating bubble under acoustic excitation and the bubble-induced synthetic jet are investigated. </LI> <LI> The output voltage and power generated from the energy harvester are measured using an electrical circuit with loads. </LI> <LI> Storage capacitor charging tests are performed with the 0.1 μF and 1 μF capacitors. </LI> <LI> This actuation technique is a simple but useful tool for energy harvesting and for potential acoustic transducers. </LI> </UL> </P>

Prevalence and Psychiatric Comorbidities of Internet Addiction in a Nationwide Sample of Korean Adults

Subin Park,HongJin Jeon,JaeNam Bae,SuJeong Seong,JinPyo Hong 대한신경정신의학회 2017 PSYCHIATRY INVESTIGATION Vol.14 No.6

The goal of the study was to examine the prevalence and psychiatric comorbidities of Internet addiction in a nationwide sample of Korean adults. Among a total of 6,022 participants involved in Korean Epidemiological Catchment Area study in 2011, 3,723 Internet users were assessed for their Internet addiction using Young’s 8-item Diagnostic Questionnaire. The results showed that of the 3,723 Internet users, 39 (1.0%) had Internet addiction. Addicted Internet users were younger, more likely to be males and unemployed compared to non-addicted Internet users. Internet addiction was associated with alcohol and nicotine use disorders, depressive disorders, and anxiety disorder after controlling for age, gender, and occupational status. Internet addiction was associated with suicidal plans even after controlling for psychiatric disorders and socio-demographic factors. This study showed that Internet addiction is highly associated with variety of different psychiatric disorders and suicidal plans. Therefore, clinicians should carefully evaluate them when treating addicted Internet users.

진동하는 버블에 의해 구동하는 소형에너지 하베스터

장대성(Deasung Jang),전진표(Jinpyo Jeon),정상국(Sang Kug Chung) 한국가시화정보학회 2016 한국가시화정보학회 학술발표대회 논문집 Vol.2016 No.4

Trifluoperazine, a Well-Known Antipsychotic, Inhibits Glioblastoma Invasion by Binding to Calmodulin and Disinhibiting Calcium Release Channel IP₃R

Kang, Seokmin,Hong, Jinpyo,Lee, Jung Moo,Moon, Hyo Eun,Jeon, Borami,Choi, Jungil,Yoon, Nal Ae,Paek, Sun Ha,Roh, Eun Joo,Lee, C. Justin,Kang, Sang Soo American Association for Cancer Research 2017 Molecular cancer therapeutics Vol.16 No.1

<P>Calcium (Ca2+) signaling is an important signaling process, implicated in cancer cell proliferation and motility of the deadly glioblastomas that aggressively invade neighboring brain tissue. We have previously demonstrated that caffeine blocks glioblastoma invasion and extends survival by inhibiting Ca2+ release channel inositol 1,4,5-trisphosphate receptor (IP3R) subtype 3. Trifluoperazine (TFP) is an FDA-approved antipsychotic drug for schizophrenia. Interestingly, TFP has been recently reported to show a strong anticancer effect on lung cancer, hepatocellular carcinoma, and T-cell lymphoma. However, the possible anticancer effect of TFP on glioblastoma has not been tested. Here, we report that TFP potently suppresses proliferation, motility, and invasion of glioblas-toma cells in vitro, and tumor growth in in vivo xenograft mouse model. Unlike caffeine, TFP triggers massive and irreversible release of Ca2+ from intracellular stores by IP3R subtype 1 and 2 by directly interacting at the TFP-binding site of a Ca2+-binding protein, calmodulin subtype 2 (CaM2). TFP binding to CaM2 causes a dissociation of CaM2 from IP3R and subsequent opening of IP3R. Compared with the control neural stem cells, various glioblastoma cell lines showed enhanced expression of CaM2 and thus enhanced sensitivity to TFP. On the basis of these findings, we propose TFP as a potential therapeutic drug for glioblastoma by aberrantly and irreversibly increasing Ca2+ in glioblastoma cells. (C) 2016 AACR.</P>

Association of Body Mass Index with Suicide Behaviors, Perceived Stress, and Life Dissatisfaction in the Korean General Population

Haesoo Kim,HongJin Jeon,JaeNam Bae,MaengJe Cho,SeongJin Cho,Hyochul Lee,JinPyo Hong 대한신경정신의학회 2018 PSYCHIATRY INVESTIGATION Vol.15 No.3

Objective The purpose of the present study was to investigate the association between Body Mass Index, suicide, perceived stress, and life dissatisfaction in a general population sample of Korean adults. Methods A total of 6,022 nationally representative adults aged 18 to 74 were selected using a multistage cross-sectional cluster sampling method. Questionnaires regarding suicide behaviors, perceived stress, and life satisfaction were completed by the participants. They also reported their heights and weights, which were used to calculate BMI. Psychiatric disorders were diagnosed according to the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition, using the Korean version of the Composite International Diagnostic Interview. Results The results showed that being underweight was associated with higher risk for suicide ideation [odds ratio (OR), 1.6; 95% confidence interval (Cl), 1.18-2.05] and suicide attempt (OR, 2.0, 95% Cl, 1.23-3.31). Likewise, obesity also increased the risk of suicide ideation (OR, 1.3; 95% Cl, 1.11-1.56) although not suicide attempt. Furthermore, underweight individuals were more likely to report severe level of perceived stress (OR, 1.7; 95% Cl, 1.26-2.17) and life dissatisfaction (OR, 1.3; 95% Cl, 1.07-1.68). All of the results remained significant after adjusting for age, gender, education, and psychiatric illnesses. Conclusion This study found that being underweight is a significant risk factor for suicide and poor subjective wellbeing in Korea. It suggests that BMI status may be an important modifiable factor for improving mental health in Korea.