Compensation method for respiratory motion in proton treatment planning for mobile liver cancer

Jeong, Hojin,Lee, Se Byeong,Yoo, Seung Hoon,Lim, Young Kyung,Kim, Tae Hyun,Park, Seyjoon,Chai, Gyu Young,Kang, Ki Mun,Shin, Dongho John Wiley and Sons Inc. 2013 Journal of applied clinical medical physics Vol.14 No.2

<P>We evaluated the dosimetric effect of a respiration motion, and sought an effective planning strategy to compensate the motion using four‐dimensional computed tomography (4D CT) dataset of seven selected liver patients. For each patient, we constructed four different proton plans based on: (1) average (AVG) CT, (2) maximum‐intensity projection (MIP) CT, (3) AVG CT with density override of tumor volume (OVR), and (4) AVG CT with field‐specific proton margin which was determined by the range difference between AVG and MIP plans (mAVG). The overall effectiveness of each planning strategy was evaluated by calculating the cumulative dose distribution over an entire breathing cycle. We observed clear differences between AV G and MIP CT‐based plans, with significant underdosages at expiratory and inspiratory phases, respectively. Only the mAVG planning strategy was fully successful as the field‐specific proton margin applied in the planning strategy complemented both the limitations of AVG and MIP CT‐based strategies. These results demonstrated that respiration motion induced significant changes in dose distribution of 3D proton plans for mobile liver cancer and the changes can be effectively compensated by applying field‐specific proton margin to each proton field.</P><P>PACS numbers: 87.55.D; 87.53.Bn; 87.53.Jw; 87.55.dk</P>

Segregation of H as a surfactant during the formation of an Ag cluster on H-terminated Si(111): First-principles total-energy calculations

Jeong, Hojin,Jeong, Sukmin American Physical Society 2006 Physical review. B, Condensed matter and materials Vol.73 No.12

Fully Dispersed Rh Ensemble Catalyst To Enhance Low-Temperature Activity

Jeong, Hojin,Lee, Geonhee,Kim, Beom-Sik,Bae, Junemin,Han, Jeong Woo,Lee, Hyunjoo American Chemical Society 2018 JOURNAL OF THE AMERICAN CHEMICAL SOCIETY - Vol.140 No.30

<P>Minimizing the use of precious metal catalysts is important in many applications. Single-atom catalysts (SACs) have received much attention because all of the metal atoms can be used for surface reactions. However, SACs cannot catalyze some important reactions that require ensemble sites. Here, Rh catalysts were prepared by treating 2 wt % Rh/CeO<SUB>2</SUB> hydrothermally at 750 °C for 25 h. Nearly 100% dispersion was obtained, but the surface Rh atoms were not isolated (denoted as ENS). They catalyzed the oxidation of C<SUB>3</SUB>H<SUB>6</SUB> or C<SUB>3</SUB>H<SUB>8</SUB> at low temperatures, but these oxidations did not occur on the Rh SAC. When the simultaneous oxidation of CO, C<SUB>3</SUB>H<SUB>6</SUB>, and C<SUB>3</SUB>H<SUB>8</SUB> was performed, the <I>T</I><SUB>20</SUB> (temperature at conversion 20%) for CO oxidation increased significantly from 40 °C for sole CO oxidation to 180 °C on SAC due to the competitive adsorption of hydrocarbons. However, <I>T</I><SUB>20</SUB> increased much less on ENS, from 60 to 100 °C. ENS exhibited superior activity for low-temperature oxidation. During hydrothermal treatment for 25 h, the Rh size initially increased from 2.3 to 6.7 nm then decreased to 0.9 nm. The surface hydroxyl groups formed on the catalyst surface help detach Rh atoms from Rh clusters, while preventing the reaggregation of dispersed Rh atoms into Rh clusters. This fully dispersed catalyst would have maximum atom-efficiency while catalyzing various surface reactions.</P> [FIG OMISSION]</BR>

Dosimetric characteristic of the use of glass dosimeter in high-energy proton beam therapy

Jeong-Eun Rah,Dong Ho Shin,Dea-Hyun Kim,Dong Wook Kim,Ui-Jung Hwang,Hojin Jeong,Sang-Yeob Lee,Doo-Hyun Lee,Myonggeun Yoon,Byeong Lee,Sung Yong Park 대한방사선방어학회 2010 대한방사선방어학회 학술발표회 논문요약집 Vol.2010 No.11

Selective hydrogenation of furanic aldehydes using Ni nanoparticle catalysts capped with organic molecules

Jeong, Hojin,Kim, Chanyeon,Yang, Sungeun,Lee, Hyunjoo Elsevier 2016 Journal of catalysis Vol.344 No.-

<P><B>Abstract</B></P> <P>Ni nanoparticles were synthesized by a colloidal method in the presence of organic surface-capping agents and used to catalyze the selective hydrogenation of unsaturated furanic aldehydes to furanic alcohols. The effects of the Ni nanoparticle size and surface organic layer were evaluated. Of the 3.7, 5.1, 6.8, and 10.4nm Ni nanoparticles tested in selective furfural (FFR) hydrogenation to furfuryl alcohol (FFA), the 6.8nm Ni nanoparticles exhibited the highest yield because access to the surface sites on the smaller and larger nanoparticles was blocked by the densely packed organic layer and by their agglomeration due to magnetic attraction, respectively. The capped Ni nanoparticles exhibited a high FFA yield of 96%, whereas significant over-hydrogenation was observed when uncapped calcined Ni/SiO<SUB>2</SUB> catalysts with similarly sized Ni nanoparticles were employed. Steric hindrance of the Ni surface induced by the organic surface layer led to selective FFR hydrogenation to FFA. The capped Ni nanoparticles could be reused repeatedly without a significant loss in the FFA yield. They also exhibited high selectivity (>90%) in the hydrogenation of other unsaturated furanic aldehydes to their corresponding alcohols.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Ni NPs capped with organic molecules showed high activity for selective hydrogenation. </LI> <LI> The surface organic molecules suppressed over-hydrogenation unlike uncapped Ni NPs. </LI> <LI> The size effect of capped and uncapped Ni NPs was estimated. </LI> <LI> The capped Ni NP catalysts can be reused up to 5 times without loss in activity. </LI> <LI> The absence of Ni ensemble sites on the capped Ni NPs was confirmed by in-situ IR. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Effect of Visual Feedback Squat Motion on Core Muscles Thickness of Young People with Lower Back Pain

( Hojin Jeong ),( Chibock Park ),( Yongnam Kim ) 대한물리치료학회 2019 대한물리치료학회지 Vol.31 No.4

Purpose: This study examined the effect of visual feedback squat on the core muscle thickness of young adults experiencing back pain. Methods: Thirty adult men and women who experienced back pain were assigned randomly to 15 members of the visual feedback squat group (VSG) and 15 of the normal squat group (NSG) to train three times a week for a total of eight weeks. The core muscle thickness was compared prior to the test for four weeks and eight weeks after the test by dividing it into warm-up exercise, main exercise, and 10 minutes finishing exercise. Before, and four weeks and eight weeks later, the thickness of the core muscle was compared using an ultrasonic imaging system. Repeated measured ANOVA was performed to compare the groups, and a Bonferroni test was performed as a post-hoc test to assess the significance of the timing of the measurements in each group according to the periods. An independent t-test was conducted to test the significance between the groups according to the measurement points. Results: A significant change in the main effects of time and interactions of the time difference in muscle thickness of transvers abdominis were observed between the visual feedback squat and control groups according to the measurement point (p< 0.05). No significant difference in the muscle thickness of both muscles was observed between the groups with the exception of the right abdominis (p >0.05). Conclusion: These findings suggest that visual feedback squat exercise is expected to have positive effects on the development of transverse abdominis in core muscles.

A 0.015-mm<tex> $^{\text{2}}$</tex> Inductorless 32-GHz Clock Generator With Wide Frequency-Tuning Range in 28-nm CMOS Technology

Jeong, Gyu-Seob,Kim, Wooseok,Park, Jaejin,Kim, Taeik,Park, Hojin,Jeong, Deog-Kyoon IEEE 2017 IEEE TRANSACTIONS ON CIRCUITS AND SYSTEMS PART 2 E Vol.64 No.6

<P>This brief illustrates the design of an inductorless high-speed clock generator. Compared to inductance-capacitance (LC) oscillators, ring oscillators are used in order to achieve a wide frequency-tuning range with a small chip area. By employing a cascaded phase-locked loop (PLL) architecture, the phase noise of the oscillator can be effectively suppressed. The first PLL is implemented with high-voltage devices under 1.8-V supply to provide a clean reference for the second PLL. The second PLL consists of only low-voltage devices, with a supply voltage of 0.9 V for high-speed operation. Following the second PLL, a clock doubler multiplies the PLL output clock by a factor of 2, which avoids power-consuming high-frequency clock dividers. In order to minimize any mismatch effects, special layout techniques are employed for the second voltage-controlled oscillator and the clock doubler. The prototype chip was fabricated in 28-nm complementary metal oxide semiconductor (CMOS) technology, and it occupies an active area of only 0.015 mm(2). The proposed PLL achieves a maximum output frequency of 32 GHz and consumes a total power of 30 mW, exhibiting a power efficiency of 0.9 mW/GHz.</P>

Effect of Visual Feedback Squat Motion on Core Muscles Thickness of Young People with Lower Back Pain

Jeong, HoJin,Park, ChiBock,Kim, YongNam 대한물리치료학회 2019 대한물리치료학회지 Vol.31 No.4

Purpose: This study examined the effect of visual feedback squat on the core muscle thickness of young adults experiencing back pain. Methods: Thirty adult men and women who experienced back pain were assigned randomly to 15 members of the visual feedback squat group (VSG) and 15 of the normal squat group (NSG) to train three times a week for a total of eight weeks. The core muscle thickness was compared prior to the test for four weeks and eight weeks after the test by dividing it into warm-up exercise, main exercise, and 10 minutes finishing exercise. Before, and four weeks and eight weeks later, the thickness of the core muscle was compared using an ultrasonic imaging system. Repeated measured ANOVA was performed to compare the groups, and a Bonferroni test was performed as a post-hoc test to assess the significance of the timing of the measurements in each group according to the periods. An independent t-test was conducted to test the significance between the groups according to the measurement points. Results: A significant change in the main effects of time and interactions of the time difference in muscle thickness of transvers abdominis were observed between the visual feedback squat and control groups according to the measurement point (p<0.05). No significant difference in the muscle thickness of both muscles was observed between the groups with the exception of the right abdominis (p>0.05). Conclusion: These findings suggest that visual feedback squat exercise is expected to have positive effects on the development of transverse abdominis in core muscles.

무전해 도금 탄소섬유 복합재 기반의 항공기 결빙보호시스템의 방빙 성능 해석

정호진(Hojin Jeong),조현승(Hyeonseung Jo),이준성(Junsung Lee),남영우(Youngwoo Nam),이학진(Hakjin Jee),명노신(Rho Shin Myong) 한국항공우주학회 2021 한국항공우주학회 학술발표회 논문집 Vol.2021 No.7

흡착원자의 덮임율에 따른 Ag/Si(111) √3×√3의 구조 변화

정호진(Hojin Jeong),정석민(Sukmin Jeong) 한국진공학회(ASCT) 2008 Applied Science and Convergence Technology Vol.17 No.5

제일원리계산 방법을 이용하여 Ag/Si(111) √3×√3 (이후로 √3-Ag로 표시) 표면에 은 원자가 추가로 흡착된 표면의 원자구조와 에너지를 조사하였다. 은의 덮임율을 0.02 ML에서 0.14 ML로 변화시켜가며 구조변화를 살펴보았다. 흡착된 은 원자들은 대부분 √3-Ag 표면의 은 원자층의 작은 삼각형(ST)의 중간에 자리 잡았다. 특이한 것은 은 원자들은 은 원자층 보다 아래로 내려간다는 것이다. 은 흡착원자(adatom)의 덮임율이 증가함에 따라 adatom들은 클러스터를 만들려는 경향을 보였다. 은 흡착원자들이 모인 클러스터의 에너지를 계산해 보면 흡착원자가 세 개일 때 가장 안정됨을 알 수 있었다. 이 삼원자 클러스터를 구성 단위로 하여 √21×√21 구조의 원자구조를 결정할 수 있었다. 각 덮임율에서 가장 에너지가 낮은 구조들에 대한 STM 영상을 시뮬레이션 해 보면 은 원자는 찬 상태에서 어둡게 보였다. 이는 은 원자가 기판으로 전하를 제공해 줌을 의미한다. 그리고 원자층의 구조변화가 STM 실험에서 보이는 미세한 특성까지도 잘 설명하였다. Using a first-principles total-energy method, we investigate structural and energy changes on Ag/Si(111) √3×√3 (√3-Ag hereafter) as the number of the additional Ag adatoms increases. The Ag coverage varies from 0.02 to 0.14 ML. Most Ag adatoms occupy the ST site, which is the center of small triangles of the substrate Ag layer that is composed of small and large triangles. One of the interesting adsorption features is that the adatoms immerse below the substrate layer. The total energy calculations show that the clusters become the most stable when the number of Ag atoms is three. This three-Ag cluster becomes the building block of the √21×√21 phase that shows a large surface conductivity. The simulated STM images show that the adatoms look dark in filled-state images while bright in empty-state images. This suggests that the adatoms donate their charge to the substrate. The simulated STM images agree well with the experimental images.