• Nuclear Engineering and Technology
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• v.53 no.6
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• pp.1970-1978
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• 2021

The aim of this study was to optimize the target, moderator, and collimator (TMC) in a neutron beam generator for the accelerator-based BNCT (A-BNCT) system. The optimization employed the Monte Carlo Neutron and Photon (MCNP) simulation. The optimal geometry for the target was decided as the one with the highest neutron flux among nominates, which were called as angled, rib, and tube in this study. The moderator was optimized in terms of consisting material to produce appropriate neutron energy distribution for the treatment. The optimization of the collimator, which wrapped around the target, was carried out by deciding the material to effectively prevent the leakage radiations. As results, characteristic of the neutron beam from the optimized TMC was compared to the recommendation by the International Atomic Energy Agent (IAEA). The tube type target showed the highest neutron flux among nominates. The optimal material for the moderator and collimator were combination of Fluental (Al₂0₃+AlF₃) with ⁶⁰Ni filter and lead, respectively. The optimized TMC satisfied the IAEA recommendations such as the minimum production rate of epithermal neutrons from thermal neutrons: that was 2.5 times higher. The results can be used as source terms for shielding designs of treatment rooms.

• Nuclear Engineering and Technology
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• v.55 no.6
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• pp.2018-2025
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• 2023

In our previous study, we proposed an integrated PG-PET-based imaging method to increase the prediction accuracy for patient dose distributions. The purpose of the present study is to experimentally validate the feasibility of the PG-PET system. Based on the detector geometry optimized in the previous study, we constructed a dual-head PG-PET system consisting of a 16 × 16 GAGG scintillator and KETEK SiPM arrays, BaSO₄ reflectors, and an 8 × 8 parallel-hole tungsten collimator. The performance of this system as equipped with a proof of principle, we measured the PG and positron emission (PE) distributions from a 3 × 6 × 10 cm³ PMMA phantom for a 45 MeV proton beam. The measured depth was about 17 mm and the expected depth was 16 mm in the computation simulation under the same conditions as the measurements. In the comparison result, we can find a 1 mm difference between computation simulation and measurement. In this study, our results show the feasibility of the PG-PET system for in-vivo range verification. However, further study should be followed with the consideration of the typical measurement conditions in the clinic application.

• Progress in Medical Physics
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• v.33 no.4
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• pp.172-179
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• 2022

Recently, tetrahedral phantoms have been newly adopted as international standard mesh-type reference computational phantoms (MRCPs) by the International Commission on Radiological Protection, and a program has been developed to convert them to computational tomography images and DICOM-RT structure files for application of radiotherapy. Through this program, the use of the tetrahedral standard phantom has become available in clinical practice, but utilization has been difficult due to various library dependencies requiring a lot of time and effort for installation. To overcome this limitation, in this study a newly developed TET2DICOM-GUI, a TET2DICOM program based on a graphical user interface (GUI), was programmed using only the MATLAB language so that it can be used without additional library installation and configuration. The program runs in the same order as TET2DICOM and has been optimized to run on a personal computer in a GUI environment. A tetrahedron-based male international standard human phantom, MRCP-AM, was used to evaluate TET2DICOM-GUI. Conversion into a DICOM-RT dataset applicable in clinical practice in about one hour with a personal computer as a basis was confirmed. Also, the generated DICOM-RT dataset was confirmed to be effectively implemented in the radiotherapy planning system. The program developed in this study is expected to replace actual patient data in future studies.

• Nuclear Engineering and Technology
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• v.55 no.10
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• pp.3907-3912
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• 2023

Radiation portal monitors (RPMs) installed at airports and harbors to prevent illicit trafficking of radioactive materials generally use large plastic scintillators. However, their energy resolution is poor and radionuclide identification is nearly unfeasible. In this study, to improve isotope identification, a RPM system based on a multi-array plastic scintillator and convolutional neural network (CNN) was evaluated by measuring the spectra of radioactive sources. A multi-array plastic scintillator comprising an assembly of 14 hexagonal scintillators was fabricated within an area of 50 × 100 cm². The energy spectra of ¹³⁷Cs, ⁶⁰Co, ²²⁶Ra, and ⁴K (KCl) were measured at speeds of 10-30 km/h, respectively, and an energy-weighted algorithm was applied. For the CNN, 700 and 300 spectral images were used as training and testing images, respectively. Compared to the conventional plastic scintillator, the multi-arrayed detector showed a high collection probability of the optical photons generated inside. A Compton maximum peak was observed for four moving radiation sources, and the CNN-based classification results showed that at least 70% was discriminated. Under the speed condition, the spectral fluctuations were higher than those under dwelling condition. However, the machine learning results demonstrated that a considerably high level of nuclide discrimination was possible under source movement conditions.

• Journal of Radiation Protection and Research
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• v.49 no.1
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• pp.29-39
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• 2024

Background: The gamma emission tomography (GET) device has been reported a reliable technique to inspect partial defects within spent nuclear fuel (SNF) of pin-by-pin level. However, the existing GET devices have low accuracy owing to the high attenuation and scatter probability for SNF inspection condition. The purpose of this study is to design and optimize a Yonsei single-photon emission computed tomography version 2 (YSECT.v.2) for fast inspection of SNF in water storage by acquisition of high-quality tomographic images. Materials and Methods: Using Geant4 (Geant4 Collaboration) and DETECT-2000 (Glenn F. Knoll et al.) Monte Carlo simulation, the geometrical structure of the proposed device was determined and its performance was evaluated for the ¹³⁷Cs source in water. In a Geant4-based assessment, proposed device was compared with the International Atomic Energy Agency (IAEA)-authenticated device for the quality of tomographic images obtained for 12 fuel sources in a 14 × 14 Westinghouse-type fuel assembly. Results and Discussion: According to the results, the length, slit width, and septal width of the collimator were determined to be 65, 2.1, and 1.5 mm, respectively, and the material and length of the trapezoidal-shaped scintillator were determined to be gadolinium aluminum gallium garnet and 45 mm, respectively. Based on the results of performance comparison between the YSECT.v.2 and IAEA's device, the proposed device showed 200 times higher performance in gamma-detection sensitivity and similar source discrimination probability. Conclusion: In this study, we optimally designed the GET device for improving the SNF inspection accuracy and evaluated its performance. Our results show that the YSECT.v.2 device could be employed for SNF inspection.

• Nuclear Engineering and Technology
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• v.55 no.11
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• pp.4019-4025
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• 2023

Recently, a new monkey computational phantom, called Visible Monkey, was developed for non-ionizing radiation studies in animal research. In this study, we extended its applications to ionizing radiation studies by implementing the voxel model of the Visible Monkey into three general-purpose Monte Carlo (MC) codes: MCNP6, PHITS, and Geant4. The implementation work for MCNP and PHITS was conducted using the LATTICE, UNIVERSE, and FILL cards. The G4VNestedParameterisation class was used for Geant4. Then, organ dose coefficients (DCs) for idealized photon beams in the antero-posterior direction were calculated using the three codes and compared, showing excellent agreement (differences <3%). Additionally, organ DCs in other directions (postero-anterior, left-lateral, and right-lateral) were calculated and compared with those of the newborn and 1-year-old reference phantoms. Significant differences were observed (e.g., the stomach DC of the monkey was 5-fold greater than that of the 1-year-old phantom at 0.03 MeV) while the differences tended to decrease with increasing energy (mostly <20% at 10 MeV). The results of this study allows conducting MC simulations using the Visible Monkey to estimate organ-level doses, which should be valuable to support/improve monkey experiments involving ionizing radiation exposures.

• Journal of Haehwa Medicine
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• v.9 no.1
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• pp.547-594
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• 2000

I. Introduction The essence of Oriental medicine consists of ancient books, experienced doctors and succeeded skills of common society. Many famous doctors studied medical science by their fathers or teachers. So the history of medical science is long. $\ll$DangDaeMyeongIImJeungJeongHwa(當代名醫臨證精華)$\gg$ written by SaWoogWang(史宇廣) and DanSeoGeon(單書健) has many medical experience of famous doctors. So it has important historical value. Bi(痺) means blocking. BiJeung is one kind of symptoms making muscles, bones and jonts feel pain, numbness or edema. For example it can be gout or SLE etc. So I studied ${\ll}BiJeungJuJip{\gg}$. II. Final Decision Following decisions of Chinese doctors of 20th century are as follows ; 1. JuYangChun(朱良春) emphasized on IkSinJangDok(益腎壯督) to treat BiJeong. And he devided WanBi(頑痺) as PungHanSeup(風寒濕), DamEo(痰瘀), YeolDok(熱毒), SinHeo(腎虛). He used insects for medicine. 2. ChoSuDoek(焦樹德) introduced past prescription. He used ChiBiTang(治痺湯) to treat HaengBi(行痺), TongBi(痛痺), ChakBi(着痺). He insisted that Han(寒; coldness) and Seup(濕; dampness) be Eum(陰) and Pung(風; wind) can change his character to be Eum. After all BiJeung is usually EumJeung. So he used GaeJi(桂枝) and BuJa(附子). By the way he used ChungYeolSanBiTang(淸熱散痺湯) for YeolBi, BoSinGeoHanChiWangTang SaBok(王士福) emphasized on the importance of medicine. He introduced many treatments like CheongYeol(情熱) for YeolBi and YiO(二烏) for HanBi. And he divided BiJeung period for three steps. At 1st step, we must use GeoSa(祛邪), at 2nd step, we must use BuJeong(扶正) and at 3rd step, we must use BoHyeol(補血), he insisted. And he introduced many herbs to treat BiJeung. 4. JeongGwangJeok(丁光迪) said that GaeJi(桂枝), MaHwang(麻黃), OYak(烏蘖) and BuJa(附子) are very important for TongRak(通絡). And pain usually results from Han(寒), so he liked to use hot-character herbs. 5. MaGi(馬志) insisted that BiJeung usually result from ChilJeong(七情). And he liked to use insects for treatment of BiJeung. 6. WeolSeokMu(越錫武) introduced 8 kinds of treatments and divided BiJeung period. Also he divided BeJeung for PungBi(風痺), HanBi(寒痺) and SeupBi(濕痺). 7. SeoGeaHam(徐季含) observed many patients and concluded that 86.7% of BiJeung is HeuJeung(虛症). 8. YuJiMyeong(劉志明) said that YeolBi is important and CheongYeol is also important. So he emphasized on DangGyuiJeomTongTang(當歸拈痛湯) and SeonBiTang(宣痺湯). 9. WangLiChu(汪履秋) studied cause of WanBi. Internal cause is GiHyeolHeo(氣血虛) and GanSinHeo(肝腎虛) and external cause is SaGi(邪氣) he insisted. 10. WangSaSang(王士相) said that YeolBi can be SeupYeolBi or EumHeuYeolBi(陰虛熱痺) and HanSeupBi(寒濕痺) is rare. He use WooBangJaSan(牛蒡子散) and BangPungHwan(防風丸) for SeupYeolBi, DangGyuiSaYeokTang(當歸四逆湯) for HanSeupBi. 11. JinTaekGang(陳澤江) treated YeolBi with BaekHoGaGyeJiTang(自虎加桂枝湯) and SaMyoSan(四妙散). If they don't have effect, he tried to cure BiJeung step by step. And he used e term of GeunBi(筋痺) and BangGiMogwaEIInTang(防己木瓜薏苡仁湯) was good for GeunBi. 12. MaSeoJeong(麻瑞亭) said that PungSeupYeokJeul(風濕歷節) is BiJeung and it is related to GanBinSin(肝脾腎; liver, Spleen, Kindey). And he emphasized on balance WiGi(衛氣) and YoungHeul(營血). 13. SaJeJu(史濟桂) said that GeunGolBi(筋骨痺) is similar to arthritis and sometimes called ChakBi. And SinBi(腎痺) is terminal stage of ChakBi, he said. He also used insects for treatment. 14. JeongJeNam(丁濟南) tried to cure SLE and used GyeJi, CheonCho(川椒), SinGeunCho(伸筋草), SunRyeongBi(仙靈脾), HyconSam(玄蔘) and GamCho(甘草). 15. JinGYungHwa(陳景和) emphasized on diagnosis of tongue. If the color of tongue is blue, it usually has EoHyeol(瘀血), for example. And he also used insects. 16. JuSongI(朱松毅) tried to devide YeolBi with OnByeong(溫病), Wi(衛), Gi(氣) and Hyeol(血). 17. RuDaBong(蔞多峰) said that JyeongHeo(正虛), OiSa(外邪) and EoHyeol are closely related. And he explained BiJeung by deviding the body into the part, for example head, neck, shoulder, waist, upper limb and lower limb. 18. YuMuBo(劉茂甫) defined PungHanSyubBi as chronic stage and YeolBi as acute stage.

• Korean Journal of Materials Research
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• v.4 no.6
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• pp.681-686
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• 1994

Microwave Detector Using $YBa_{2}Cu_{3}O_{7-x}$, Grain Boundary Junction $YBa_{2}Cu_{3}O_{7-x}$ superconductor thin films were deposited on $LaAIO_{3}$ (100) single crystal substrates using a metal organic chemical vapor deposition (MOCVD) method. These films showed the critical temperature of about 9OK and critical current density of over $10^5/A \textrm{cm}^2$at 77K. These films showed granular structure with 0.5~1.5$\mu \textrm{m}$ grains. Bridge-type junctions, 6$\mu \textrm{m}$ in width and 6pm in length, were fabricated using the photolithography and the Ar ion milling techniques. Current-voltage (I-V) characteristics of these junctions with the microwave irradiation at 77K were studied. The critical current densities decreased as the irradiated microwave power increased. When microwaves were irradiated on the bridge at 77K. the I-V charateristics showed constant voltage stcp(Shapiro steps) at $\Delta$=nho/2e.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.22 no.1
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• pp.11-14
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• 2012

The AlGaN layer has direct wide bandgaps ranging from 3.4 to 6.2 eV. Nowadays, it is becoming more important to fabricate optical devices in an UV region for the many applications. The high quality AlGaN layer is necessary to establish the UV optical devices. However, the growth of AlGaN layer on GaN layer is difficult due to the lattice mismatch and difference thermal expansion coefficient between GaN layer and AlGaN layer. In this paper, we attempted to grow the LED structure on GaN template by mixed-source HVPE method with multi-sliding boat system. We tried to find the optical and lattice transition of active layer by control the Al content in mixed-source. For the growth of epi layer, the HCl and $NH_3$ gas were flowed over the mixed-source and the carrier gas was $N_2$. The temperature of source zone and growth zone was stabled at 900 and $1090^{\circ}C$, respectively. After the growth, we performed the x-ray diffraction (XRD) and electro luminescence (EL) measurement.

• MALSORI
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• no.27_28
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• pp.27-56
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• 1994

Processes involving the change of vowel height are natural enough to be found in many languages. It is essential to have a better feature specification for vowel height to grasp these processes properly, Standard Phonology adopts the binary feature system, and vowel height is represented by the two features, i.e., [\pm high] and [\pm low]. This has its own merits. But it is defective because it is misleading when we count the number of features used in a rule to compare the naturalness of rules. This feature system also cannot represent more than three degrees of height, We wi31 discard the binary features for vowel height. We consider to adopt the multivalued feature [n high] for the property of height. However, this feature cannot avoid the arbitrariness resulting from the number values denoting vowel height. It is not easy to expect whether the number in question is the largest or not It also is impossible to decide whether a larger number denotes a higher vowel or a lower vowel. Furthermore this feature specification requires an ad hoc condition such as n > 3 or n \geq 2, whenever we want to refer to a natural class including more than one degree of height The altelnative might be Particle Phonology, or Dependency Phonology. These might be apt for multivalued vowel height systems, as their supporters argue. However, the feature specification of Particle Phonology will be discarded because it does not observe strictly the assumption that the number of the particle a is decisive in representing the height. One a in a representation can denote variant degrees of height such as [e], [I], [a], [a ] and [e ]. This also means that we cannot represent natural classes in terms of the number of the particle a, Dependency Phonology also has problems in specifying a degree of vowel height by the dependency relations between the elements. There is no unique element to represent vowel height since every property has to be defined in terms of the dependency relations between two or more elements, As a result it is difficult to formulate a rule for vowel height change, especially when the phenomenon involves a chain of vowel shifts. Therefore, we suggest a new feature specification for vowel height (see Chapter 3). This specification resorts to a single feature H and a few >'s which refer exclusively to the degree of the tongue height when a vowel is pronounced. It can cope with more than three degrees of height because it is fundamentally a multivalued scalar feature. This feature also obviates the ad hoc condition for a natural class while the [n high] type of multivalued feature suffers from it. Also this feature specification conforms to our expection that the notation should become simpler as the generality of the class increases, in that the fewer angled brackets are used, the more vowels are included, Incidentally, it has also to be noted that, by adopting a single feature for vowel height, it is possible to formulate a simpler version of rules involving the changes of vowel height especially when they involve vowel shifts found in many languages.