Pulse pileup correction method for gamma-ray spectroscopy in high radiation fields

Lee, Minju,Lee, Daehee,Ko, Eunbie,Park, Kyeongjin,Kim, Junhyuk,Ko, Kilyoung,Sharma, Manish,Cho, Gyuseong Korean Nuclear Society 2020 Nuclear Engineering and Technology Vol.52 No.5

The detector suffers from pulse pileup by overlapping of the signals when it was used in high radiation fields. The pulse pileup deteriorates the energy spectrum and causes count losses due to random co-incidences, which might not resolve within the resolving time of the detection system. In this study, it is aimed to propose a new pulse pileup correction method. The proposed method is to correct the start point of the pileup pulse. The parameters are obtained from the fitted exponential curve using the peak point of the previous pulse and the start point of the pileup pulse. The amplitude at the corrected start point of the pileup pulse can be estimated by the peak time of the pileup pulse. The system is composed of a NaI (Tl) scintillation crystal, a photomultiplier tube, and an oscilloscope. A 61 μCi ¹³⁷Cs check-source was placed at a distance of 3 cm, 5 cm, and 10 cm, respectively. The gamma energy spectra for the radioisotope of ¹³⁷Cs were obtained to verify the proposed method. As a result, the correction of the pulse pileup through the proposed method shows a remarkable improvement of FWHM at 662 keV by 29, 39, and 7%, respectively.

A new cross-detection method for improved energy-resolving photon counting under pulse pile-up

Lee, Daehee,Lim, Kyung Taek,Park, Kyungjin,Lee, Changyeop,Cho, Gyuseong Elsevier 2017 Nuclear instruments & methods in physics research. Vol.867 No.-

<P><B>Abstract</B></P> <P>In recent, photon counting detectors (PCDs) have been replacing the energy-integrating detectors in many medical imaging applications due to the formers‘ high resolution, low noise, and high efficiency. Under a high flux X-ray exposure, however, a superimposition of pulses, i.e., pulse pile-up, frequently occurs due to the finite output pulse width, causing distortions in the energy spectrum as a consequence. Therefore, pulse pile-up is considered as a major constraint in using PCDs for high flux X-ray applications. In this study, a new photon counting method is proposed to minimize degradations in PCD performance due to pulse pile-up. The proposed circuit was incorporated into a pixel with a size of 200 × 200 μ <SUP> m 2 </SUP> . It was fabricated by using a 1-poly 6-metal 0 . 18 μ m complementary metal–oxide–semiconductor (CMOS) process and had a power consumption of 7 . 8 μ W ∕ pixel . From the result, it was shown that the maximum count rate of the proposed circuit was increased by a factor of 4.7 when compared to that of the conventional circuit at the same pulse width of 700 ns. This implies that the energy spectrum obtained by the proposed circuit is 4.7 times more resistant to distortions than the conventional energy-resolving circuit does under higher X-ray fluxes.</P>

Performance of and methanogenic communities involved in an innovative anaerobic process for the treatment of food wastewater in a pilot plant.

Lee, Seungyong,Lee, Bowon,Han, Gyuseong,Yoon, Heechul,Kim, Woong Japan Society for Bioscience, Biotechnology, and A 2015 Bioscience, Biotechnology, and Biochemistry Vol.79 No.8

<P>In this study, dual-cylindrical anaerobic digesters were designed and built on the pilot plant scale for the improvement of anaerobic digestion efficiency. The removal efficiency of organics, biogas productivity, yield, and microbial communities was evaluated as performance parameters of the digester. During the stable operational period in the continuous mode, the removal efficiencies of chemical oxygen demand and total solids were 74.1 and 65.1%, respectively. Biogas productivities of 63.9?m(3)/m(3)-FWW and 1.3?m(3)/kg-VSremoved were measured. The hydrogenotrophic methanogen orders, Methanomicrobiales and Methanobacteriales, were predominant over the aceticlastic methanogen order, Methanosarcinaceae, probably due to the tolerance of the hydrogenotrophs to environmental perturbation in the field and their faster growth rate compared with that of the aceticlastics.</P>

Radiation safety analysis for the A-BNCT facility in Korea

Lee, Eunjoong,Lee, Cheol-Woo,Cho, Gyuseong Elsevier 2018 Applied radiation and isotopes Vol.142 No.-

<P><B>Abstract</B></P> <P>A Proton <I>A</I>ccelerator based <I>B</I>oron <I>N</I>eutron <I>C</I>apture <I>T</I>herapy (A-BNCT) facility is under development in Korea. Neutron beams for treatment are produced from a beryllium (Be) target and an 8 mA, 10 MeV proton beam. The purpose of the research is a radiation shielding analysis and an activation analysis for the facility design satisfying the radiation safety requirements as well as obtaining an operating license for the radiation facility according to a domestic nuclear commissioning procedure. The radiation shielding analysis was performed using the MCNPX computational particle transport code. The radiation source terms in the facility were evaluated and utilized in the shielding calculations. The minimum concrete thickness satisfying the designated dose rate of 5 μSv/h for the worker's area and 0.25 μSv/h for the public area were estimated and applied to the design. For an assessment of the radiation safety inside the facility, the dose rates were evaluated at several positions, such as behind the shielding door, around the primary barriers near the radiation sources, and in the penetrations of the ducts. The dose rate distribution was mapped for verification of the radiation safety for the entire facility. An activation analysis was carried out for the concrete walls, air, target assembly, beryllium target, and cooling water using FISPACT-2010 code. Concentrations of the activation products and dose rate induced by the radionuclides after shutdown were evaluated for the purpose of safe operation of the facility. The results were reviewed with the radiation safety regulations in Korea. As a result, it was proved that the final facility design satisfies the safety requirements.</P> <P><B>Highlights</B></P> <P> <UL> <LI> A Proton <I>A</I>ccelerator based <I>B</I>oron <I>N</I>eutron <I>C</I>apture <I>T</I>herapy (A-BNCT) facility is under development in Korea. </LI> <LI> Radiation shielding analysis was carried out using MCNPX code </LI> <LI> The facility design was determined satisfying designated dose limit </LI> <LI> Neutron activation analysis was performed with MCNPX and FISPACT code </LI> <LI> The concentration of radionuclides were reviewed with the radiation safety regulations. </LI> </UL> </P>

Study on collimator design for Neutron Science Facility of RAON accelerator complex

Lee, Eunjoong,Lee, Cheol-Woo,Yang, Sung-Chul,Lee, Young-Ouk,Cho, Gyuseong Elsevier 2018 Nuclear Instruments & Methods in Physics Research. Vol.902 No.-

<P><B>Abstract</B></P> <P>The RAON heavy ion accelerator complex is under development for the Rare Isotope Science Project (RISP) in Korea. The Neutron Science Facility (NSF) in RAON will perform Time of Flight (TOF) experiments in order to measure cross section data of fast neutrons. Fast neutrons are produced from a graphite target irradiated by a 53 MeV of deuteron beam. Consequently, a collimator that provides a highly focused neutron beam to the TOF system while reducing the background in the TOF hall should be considered. The collimator was designed by optimizing several design parameters such as the beam channel diameter, beam channel shape, and collimator type. Additionally, for the safety of workers during the operation of the NSF, an activation analysis was carried out. As a result, the final design of the collimator for the RAON NSF has a 4 m length, and channel of 0.5/2 cm in the entry/exit radius in a conical-opened shape. Materials were arranged in a ring type by setting 1 cm of the iron inside, and 20 cm of 5% borated polyethylene outside. With the final design of the collimator, a 95.7% background reduction was achieved while maintaining the original neutron beam intensity. The shut-down dose rate inside the TOF room satisfies the exposure limit</P>

[Vascular Surgery] Portomesenteric Vein Reconstruction by End-to-end Anastomosis or Interposition with Allograft in Pancreatic Cancer Surgery

Sujeong Lee,Yangjin Park,Jinseok Heo,Inwong Han,Sanghyun Shin,Jaeberm Park,Gyuseong Choi,Kyowon Lee,Minkyu Kim,Shinseok Yang 대한외과학회 2021 대한외과학회 학술대회 초록집 Vol.2021 No.11

Optimizing Ganoderma lucidum Mycelial Production Using Swine Wastewater as a Substrate

Jangwoo LEE,Jinmo AHN,Gyuseong HAN,Joonyeob LEE,Taewoan KOO,Seokhwan HWANG 한국생물공학회 2014 한국생물공학회 학술대회 Vol.2014 No.10

효율적 미세 조정을 통한 사전학습 모델의 일반화 성능 손실 방지

이규성(Gyuseong Lee),장우석(Wooseok Jang),김진현(Jin Hyeon Kim),정재우(Jaewoo Jung),조한상(Hansang Cho),안승준(Seungjun An),김경년(Gyeongnyeon Kim),김승룡(Seungryong Kim) 대한전자공학회 2023 대한전자공학회 학술대회 Vol.2023 No.6

Learning robust vision models that perform well in situations of out-of-distribution (OOD) is an important task for model deployment in real-world settings. This field has been actively researched for a long time and many proposed works achieved small performance gain compared to the simplest empirical risk minimization (ERM) method which was evaluated on a benchmark of restricted hyperparameter search space. We verify that the most effective methods are ensembling diverse models and scaling up the size of pretraining. Next, we focus on exploiting the knowledge of large pretrained models to solve domain generalization problems. However previous works have proven that naively fine-tuning a large pretrained model harms the OOD robustness. By incorporating parameter-efficient fine-tuning (PEFT) methods to large pretrained models we can effectively mitigate the loss of OOD robustness and achieve state-ofthe-art performance in domain generalization tasks.

MZ세대 소비자의 SNS 능동 적 참여도를 높이기 위한 인스타그램 및 유튜브 활용 전략 - 편의점 3사(CU, GS25, 7ELEVEN)를 중심으로 -

이희정 ( Lee Heejung ),박지인 ( Park Jiin ),김해찬 ( Kim Haechan ),김우진 ( Kim Woojin ),이규성 ( Lee Gyuseong ),노은주 ( Noh Eunju ),최은서 ( Choi Eunseo ) 한국고객만족경영학회 2021 고객만족경영연구 Vol.23 No.4

4차 산업혁명시대가 도래함에 따라 빅데이터의 중요성이 더욱 강조되고 있으며, 정보기술의 발전과 함께 데이터의 중요성은 갈수록 높아지고 있고 빅데이터의 활용은 기업의 핵심가치가 되었다. 코로나 19 사태로 인해 온라인 기반의 비대면(untact) 활동이 급격하게 증가하면서 디지털 경제로의 전환이 가속화되어 기업들은 디지털을 활용한 소비자와의 소통이 어느때 보다 더 중요해졌다. 특히 MZ세대는 트랜드를 주도하는 주요 소비자층으로 자리 잡고 있으며, SNS 매체 등 디지털 환경을 기반으로 활발하게 소비활동을 하고 있어 기업은 이들을 소구하기 위해서 SNS를 적극적으로 활용하는 방안이 절실하게 필요한 시점이다. 편의점은 일상생활에 대한 영향력과 비중이 지속적으로 확대되고 있으며, 특히 편의점 간편식은 젊은 세대와 가구들을 중심으로 폭발적 인기를 누리고 있다. 따라서 편의점을 이용하는 소비자들의 구매행동에 영향을 미칠 수 있는 SNS 마케팅은 기업의 중요한 전략으로 떠오르고 있다. 본 연구는 혼합적 연구분석 방법(mixed methodology)을 사용하여 설문조사 방법 뿐만 아니라 소비자들의 소리를 체계적으로 분석하기 위해 비정형 데이터 분석을 함으로써 보다 더 현실적으로 소비자들의 의견을 파악하고자 하였고 이를 바탕으로 향후 편의점 산업이 어떻게 MZ세대 소비자들의 SNS 능동적 참여도를 이끌어 낼 수 있는지에 대해 전략을 제안하고자 한다. 설문조사를 통해 20~30대 소비자들이 기업 SNS에 능동적으로 참여하도록 유도하기 위한 소셜미디어를 사용하는 중요한 동기를 파악하였고, 주로 사용하는 SNS 매체, 즉 유튜브와 인스타그램에 따라서 소비자의 이용동기가 다를 것인지를 확인하였다. 또한 이와 동시에 비정형 데이터, 즉 텍스트 데이터를 분석하고자 뉴스미디어 자료 및 인스타그램, 유튜브에 올라온 댓글을 분석함으로써 현재 소비자들이 소셜미디어 매체를 어떻게 활용하고 있는지를 살펴보았다. 텍스트 마이닝을 통해 시장의 소리를 파악해 봄으로써 향후 유통산업이 어떻게 MZ 소비자들을 대상으로 효율적인 SNS 전략을 구사할 수 있을 것인지를 제안하였다. The importance of big data is becoming more emphasized, and with the development of information technology, the use of big data has become the core value of companies. The rapid increase in online-based untact activities has accelerated the transition to the digital economy, leading communication skills more important than ever for companies to interact with consumers using digital tools. In particular, the MZ generation is a major consumer base leading the trend and is actively engaged in consumption activities utilizing digital environments such as SNS media, so it is critical for marketers to actively use SNS to appeal for them. Convenience stores continue to expand their influence and weight on daily life, and instant foods are enjoying explosive popularity, especially among the young customers. Therefore, SNS marketing of convenience stores is critical tool to appeal for MZ generation. This study attempted to investigate the significant SNS usage motivations that can attract MZ generation by utilizing mixed methods. Based on results, we suggest strategies on how the convenience store industry can attract active SNS participation for young generation. Through the survey, we identified important motivations of using social media and suggest the effective ways to encourage consumers in their 20s and 30s to actively participate in corporate SNS. Also we investigate whether consumers' usage of YouTube and Instagram is different in the context of usage and SNS participation. We analyzed news media data, Instagram, and comments posted on YouTube in order to examine how consumers are currently using social media. By grasping the voice of the consumers through text mining, it was suggested how the distribution industry is able to utilize efficient SNS strategies for MZ consumers.

Anaerobic Fermentation of Ulva pertusa for the Production of Organic Acids and Methane

Gyuseong HAN,Joonyeop LEE,Taewoan KOO,Seokhwan HWANG 한국생물공학회 2014 한국생물공학회 학술대회 Vol.2014 No.10