Gamma-ray spectroscopy, which is an appropriate method to identify and quantify radionuclides, is widely utilized in radiological leakage monitoring of nuclear facilities, assay of radioactive wastes, and decontamination evaluation of post-processing such as decommissioning and remediation. For example, in the post-processing, it is conducted to verify the radioactivity level of the site before and after the work and decide to recycle or dispose the generated waste. For an accurate evaluation of gamma-ray emitting radionuclides, the measurement should be carried out near the region of interest on site, or a sample analysis should be performed in the laboratory. However, the region is inaccessible due to the safety-critical nature of nuclear facilities, and excessive radiation exposure to workers could be caused. In addition, in the case of subjects that may be contaminated inside such as pipe structures generated during decommissioning, surveying is usually done over the outside of them only, so the effectiveness of the result is limited. Thus, there is a need to develop a radiation measurement system that can be available in narrow space and can sense remotely with excellent performance. A liquid light guide (LLG), unlike typical optical fiber, is a light guide which has a liquid core. It has superior light transmissivity than any optical fiber and can be manufactured with a larger diameter. Additionally, it can deliver light with much greater intensity with very low attenuation along the length because there is no packing fraction and it has very high radiation resistant characteristics. Especially, thanks to the good transmissivity in UV-VIS wavelength, the LLG can well transmit the scintillation light signals from scintillators that have relatively short emission wavelengths, such as LaBr3:Ce and CeBr3. In this study, we developed a radiation sensor system based on a LLG for remote gamma-ray spectroscopy. We fabricated a radiation sensor with LaBr3:Ce scintillator and LLG, and acquired energy spectra of Cs-137 and Co-60 remotely. Furthermore, the results of gamma-ray spectroscopy using different lengths of LLG were compared with those obtained without LLG. Energy resolutions were estimated as 7.67%, 4.90%, and 4.81% at 662, 1,173, and 1,332 keV, respectively for 1 m long LLG, which shows similar values of a general NaI(Tl) scintillator. With 3 m long LLG, the energy resolutions were 7.92%, 5.48%, and 5.07% for 662, 1,173, and 1,332 keV gamma-rays, respectively.

Recently, an international issue due to the discharge of contaminated water from the Fukushima has been highlighted. Since the Fukushima nuclear power plant accident in japan, marine environmental radioactivity survey has been strengthened with increased sampling frequency and range for seawater in territorial waters. And a stationary underwater radiation monitoring system including floating equipment-based system such as oceanographic buoys, tidal stations have been deployed on-site to detect abnormal radiological events. However, stationary monitoring systems may be insufficient for the early detection of abnormal radioactivity over a wide area, since it is a passive way of waiting for radioactive materials to spread in the ocean. So, our team developed a ship-mounted seawater gammaray monitoring system that can be operated remotely and in real time. In this study, it includes a detailed description of the design, installation, monitoring method, and operation of the system.

To obtain the gamma-ray energy spectrum of artificial radionuclides which is difficult to obtain practically, virtual gamma-ray energy spectrum simulator program was developed. It can be applied for the predetermined measurement condition for which the database was developed through computational simulation and actual measurement of background radiation. For gamma spectrometry training for KHNP HPGe detectors using this program, the database for KNPG HPGe detectors was developed. First, the geometry of the detector in the simulation was adjusted to resemble the real structure by comparing the actually measured net counts rate at the main gamma peak with the value simulated by MCNP6. The Certified Reference material (CRM) of 137Cs and 60Co were used for verification. The comparison was made with respect to the situation where CRM was attached to the top and side of the detection part of the considered detector. The geometry structures of detectors were simulated by reflecting the design drawing of the products, and the simulation was performed for several thicknesses of the Ge/Li dead layer in consideration of the change in the thickness over time. As the results, the simulation geometry was tuned so that the results for 137Cs showed a difference within 10% for all detectors. At this time, in some detectors, the result for 60Co shows a 10% higher error, which is estimated to be due to the random summing. It was not considered in tuning the simulation geometry, but it was found that improvements were needed to reflect the coincidence summing when construction the virtual spectrum in the future. The determined simulation geometry was applied to generate theoretical gamma-ray energy spectra of representative artificial radionuclides. In order to create a virtual spectrum similar to the real one, the background spectrum was measured for each detector without a source, and the simulation results were calculated in the form of having the same energy channel as the background spectrum. The background spectrum and theoretical spectra of artificial radionuclides for each detector were databased so that virtual spectra could be generated under desired conditions. The virtual spectrum was generated by adding a background spectrum and a spectrum obtained by multiplying the spectrum of the desired nuclide by the concentration of the nuclide. The validity of generated virtual spectra was verified using the pre-developed gamma spectrometry program. As a results of gamma spectrometry of virtual spectra, the virtual spectra was verified by showing a difference within 20% from the radioactivity value input when generating the virtual spectra.

Using I-band images of 35 nearby (z < 0.1) type 1 active galactic nuclei (AGNs) obtained with Hubble Space Telescope, selected from the 70-month Swift-BAT X-ray source catalog, we investigate the photometric properties of the host galaxies. With a careful treatment of the point-spread function (PSF) model and imaging decomposition, we robustly measure the I-band brightness and the effective radius of bulges in our sample. Along with black hole (BH) mass estimates from single-epoch spectroscopic data, we present the relation between BH mass and I-band bulge luminosity (MBH–MI,bul relation) of our sample AGNs. We find that our sample lies offset from the MBH–MI,bul relation of inactive galaxies by 0.4 dex, i.e., at a given bulge luminosity, the BH mass of our sample is systematically smaller than that of inactive galaxies. We also demonstrate that the zero point offset in the MBH–MI,bul relation with respect to inactive galaxies is correlated with the Eddington ratio. Based on the Kormendy relation, we find that the mean surface brightness of ellipticals and classical bulges in our sample is comparable to that of normal galaxies, revealing that bulge brightness is not enhanced in our sample. As a result, we conclude that the deviation in the MBH–MI,bul relation from inactive galaxies is possibly because the scaling factor in the virial BH mass estimator depends on the Eddington ratio.

분화국화 ‘솔라에그(등록번호 8569)’는 2015년 경상남도농 업기술원 화훼연구소에서 분홍색 ‘포인트에그’를 감마선 처리 를 하여 육성하였다. 특성검정과 형질 안정성은 2017년에서 2018년까지 3회를 수행하였다. ‘솔라에그’는 분홍색 꽃잎(54D) 과 적자색 중심부(59B)를 가진 ‘아네모네’ 형태이다. 꽃과 잎 색깔과 모양에서는 ‘솔라에그’와 ‘포인트에그’ 간의 차이는 거 의 없었다. ‘솔라에그’의 식물체와 개화 연구에서 조명과 억제 재배를 했을 때 약 42일로 개화소요시간은 비슷했다. 그러나 초장, 꽃 크기, 꽃 중심부 크기와 착화수에서 ‘포인트에그’와 비교했을 때 차이가 있었다. 특히, 자연재배조건에서 꽃 크기 는 4cm으로 대조품종과 비교했을 때 컸다. 국화 품종에서는 꽃의 크기가 상업적으로 중요한 형질이다. ‘솔라에그’의 표현 형과 개화기 연구와 비교하여 배수성, RAPD, 세포 크기 및 수 분석을 하였다. 이들 결과에서는 표현형의 변화는 작은 유전 적 변이와 세포 분열 증가와 관련이 있을 것이라고 추정하고 있다. 중형 크기의 ‘솔라에그’는 분화국화로 이용되며 농가의 평균소득 증대를 기대할 수 있다.

Despite having a low electrical conductivity, graphene oxide (GO) is used as an anode material in lithium-ion batteries (LIBs) owing its good processability in large quantities. GO is reduced by chemical or thermal treatments to enhance its electrical conductivity. In this study, high-performance GO anodes with polydopamine (PDA) and polyethylenimine (PEI) as binders were fabricated. Gamma (γ)-ray irradiation was applied to the GO–PDA–PEI hybrid sheets to covalently cross-link the GO sheets and binders with an amide bond. The covalent crosslinking was confirmed by Fourier-transform infrared spectroscopy analysis. Further, X-ray photoelectron spectroscopy results showed that γ-ray irradiation produced a reduced GO sheet, which resulted in an increase in the electrical conductivity by 30%. By characterizing the electrochemical properties, we found that the γ-ray irradiation facilitates the stability and increases the charge/discharge capacity by crosslinking GO and PDA–PEI binders and reducing the GO sheets.

Lately, Raman spectroscopy has become powerful tool for quality assessment of graphene analogues with identification of intensity ratio of Raman active D-band and G-band ( ID/IG ratio) as a vital parameter for quantification of defects. However, during chemical reduction of graphitic oxide (GrO) to reduced GrO (RGrO), the increased ID/ IG ratio is often wrongly recognized as defect augmentation, with “formation of more numerous yet smaller size sp2 domains” as its explanation. Herein, by giving due attention to normalized peak height, full-width half-maxima and integrated peak area of Raman D- and G-bands, and compliment the findings by XRD data, we have shown that in-plane size of sp2 domains actually increases upon chemical reduction. Particularly, contrary to increased ID/ IG ratio, the calculated decrease in integrated peak area ratio ( AD/AG ratio) in conjunction with narrowing of D-band and broadening of G-band, evinced the decrease in in-plane defects. Finally, as duly supported by reduction induced broadening of interlayer-spacing characteristic XRD peak and narrowing of ~ 43° centered XRD hump, we have also shown that the sp2 domains actually expands in size and the observed increase in ID/ IG ratio is indeed due to increase in across-plane defects, formed via along-the-layer slicing of graphitic domains.

Metal three-dimensional (3D) printing is an important emerging processing method in powder metallurgy. There are many successful applications of additive manufacturing. However, processing parameters such as laser power and scan speed must be manually optimized despite the development of artificial intelligence. Automatic calibration using information in an additive manufacturing database is desirable. In this study, 15 commercial pure titanium samples are processed under different conditions, and the 3D pore structures are characterized by X-ray tomography. These samples are easily classified into three categories, unmelted, well melted, or overmelted, depending on the laser energy density. Using more than 10,000 projected images for each category, convolutional neural networks are applied, and almost perfect classification of these samples is obtained. This result demonstrates that machine learning methods based on X-ray tomography can be helpful to automatically identify more suitable processing parameters.

본 논문은 1939-1941년까지 듀크 엘링턴(Duke Eliington) 밴드에서 베이스를 담당하던 지미 블 랜튼(Jimmy Blanton)과 그의 연주를 영향 받은 거장 베이스 연주자 레이 브라운(Ray brown)의 즉 흥연주 비교 논문이다. 이 연구의 목적은 재즈 더블 베이스의 역할의 다양성과 라인의 변화가 어 떻게 시작되었고 발전되어 왔는지를 인지할 수 있도록 하고, 그것으로 인해 연주자들이 다양한 음악적인 접근과 시도로 음악적의 넓은 접근을 할 수 기여할 수 있도록 하는 데 목적이 있다. 지미 블랜튼은 처음으로 모던한 재즈 베이스 연주 스타일을 선보였던 베이스 연주자이며 레이 브라운은 모드 스케일의 사용과 잦은 반음사용이 특징인 비밥 시대를 대표하는 베이스 연주자였 다. 본 논문은 먼저 1930년대 스윙시대의 음악적 배경, 지미 블랜튼과 레이 브라운의 생애와 연주 스타일을 살펴보았고, 두 연주자가 듀크 엘링턴과 연주한 공통적인 연주곡인 <Pitter Panther Patter> 을 각 마디별로 나타난 특징을 분석하여 비교하였다. 그 결과 지미 블랜튼과 레이 브라운 의 즉흥연주 공통점은 잦은 코드톤의 사용과 다양한 스케일의 사용, 패턴의 사용, 선행음의 사용, 리듬의 변화를 통한 다이나믹 연출 등이 분석되었다. 또한 레이 브라운의 연주에서 나타난 특징인 특징음을 코드톤과 연결하여 사용하여 마이너적인 느낌의 연주를 하는 것이 지미 블랜튼의 연주에 서 시작되었다는 결론이 도출되었다. 그러나 <Pitter Panther Patter>곡의 특성상 패턴적인 멜로 디와 짧은 솔로 브레이크로 좀 더 다양한 특징이 분석되지 못한 것이 본 논문의 한계점이라 할 수 있다.