Detecting Bitcoin Transactions Related to Illicit Behaviors on Dark-web Marketplace

Terresa Kim,Yongmu Suh 한국경영정보학회 2017 한국경영정보학회 학술대회논문집 Vol.2017 No.12

The anonymity of Bitcoin transaction has let Bitcoin be used as a medium of illicit activities in the dark-net marketplace that are related to crimes such as selling drugs, weapon, etc. Detecting illicit Bitcoin transaction has been drawing attention from government agencies and academia, since FBI’s investigation from 2011 to 2013, when FBI seized a marketplace, SilkRoad, which trades illicit goods and services only with Bitcoin. However, little research has been conducted to detect illicit Bitcoin transactions. In this paper, we applied data mining approach to detect illicit Bitcoin transaction using a dataset which consists of illicit Bitcoin transaction data released by FBI and legal Bitcoin transaction data. We built several classification models such as RandomForest, Decision Tree(C5.0), and SVM. 10-fold cross-validation reveals that RandomForest outperforms the other two. It is expected that we can reduce the investigation time and cost to detect illicit Bitcoin transactions.

The Weathering Resistance of Sol-Gel Derived Anti - Reflective SiO₂-TiO₂ Thin Films

Sangmoon Kim(김상문),Yongmu Lim(임용무),Kyuseog Hwang(황규석) 한국안광학회 1998 한국안광학회지 Vol.3 No.1

A transparent and colorless 80 SiO₂-20TiO₂(mol%) thin films on soda-lime-silica slide glass and sapphire substrate were obtained by spin-coating technique using tetraethyl orthosilicate and titanium trichloride as starting materials. The prepared film annealed at 750℃ showed a high transmittance and a low reflectance. For the SiO₂-TiO₂ films on slide glasses, a strong interaction between the sodium ion and oxygens is properbly the origin of the good stability to the high temperature and the high humidity.

Preparation of SiO₂-TiO₂-M<SUB>x</SUB>O<SUB>y</SUB> ( M = Co , Cr or Cu ) Thin Films by the Chemical Solution Process

Sangmoon Kim(김상문),Yongmu Lim(임용무),Kyuseog Hwang(황규석) 한국안광학회 1998 한국안광학회지 Vol.3 No.1

Glass films of SiO₂-TiO₂-M_mO_y (M = Co, Cr or Cu) have been prepared on soda-lime-silica slide glasses by the chemical solution method using a spin-coating technique. Commercially available tetraethyl orthosilicate, titanium trichloride, and cobalt-, chromium- and copper-nitrates were used as starting materials. No crystalline segregations of Co₃O₄, Cr₂O₃ and CuO were observed by X-ray diffraction θ -2 θ scans. From the optical transmission analysis, cobalt existed as Co^(2+) in tetrahedral coordination, chromium as Cr^(h+) in tetrahedral symmetry and copper as Cu^(2+) in octahedral coordination. Films with a crack-free and no texture exhibited homogeneous interfaces between the films and the substrates along the cross-section.

졸-겔법에 의한 SiO₂-TiO₂-M<SUB>x</SUB>O<SUB>y</SUB>(M = Cu , Co , Cr ) 계 박막의 제조 및 색상에 관한 연구

김상문(Sangmoon Kim),임용무(Yongmu Lim),황규석(Kyuseog Hwang) 한국안광학회 1998 한국안광학회지 Vol.3 No.1

This paper reports the preparation and characterization of colored coatings of SiO₂- TiO₂-M_xO_y (M = Co, Cr or Cu). Films of different compositions ranging from a molar content of transition metals of 5% to 20% have been prepared on soda-lime-silica slide glasses by the sol-gel process. The films have been characterized by a photospectroscopy. The color and reflectance of the films was expressed in Lab color chart and on spectra plot. `L` as lightness and all reflectance decreased with increase of the content of transition metals. The coating of Co, Cu and Cr cotaining system showed light blue, green and lemon-yellowish color, respectively.

용액법에 의한 SiO₂-TiO₂-AgO 계 박막의 제조 및 특성에 관한 연구

김상문(Sangmoon Kim),심문식(MoonSik Shim),임용무(Yongmu Lim),황규석(Kyuseog Hwang) 한국안광학회 1998 한국안광학회지 Vol.3 No.1

Coating films of SiO₂TiO₂AgO have been prepared on soda-lime-silica slide glasses and single crystal silicon wafer by the sol-gel method using a spin-coating technique. Commercially available tetraethyl orthosilicate, titanium trichloride, and silver-nitrates were used as starting materials. The heat treatment temperature of this coating films was 500 properly, obtained from TG-DTA result. The films with thickness of 310 nm were prepared by 5 times coating. In the case of l0 mol% AgO, the film showed a crack-free and smooth surface, but the higher Ago content exhibited the more pin hole and the segregated cluster of AgO. The IR absorbance of the films decreased in the range of 400 nm to 700 nm with the increase of annealing temperature. And the reflectance of the coating films decreased and the color was changed light yellow to white yellow with the increase of Ago content.

The Weathering Resistance of Sol-Gel Derived Anti-Reflective SiO₂-Tio₂ Thin Films

김상문,임용무,황규석,Kim, Sangmoon,Lim, Yongmu,Hwang, Kyuseog 한국안광학회 1998 한국안광학회지 Vol.3 No.1

A transparent and colorless $80SiO_2-20TiO_2$(mol%) thin films on soda-lime-silica slide glass and sapphire substrate were obtained by spin-coating technique using tetraethyl orthosilicate and titanium trichloride as starting materials. The prepared film annealed at $750^{\circ}C$ showed a high transmittance and a low reflectance. For the $SiO_2-TiO_2$ films on slide glasses, a strong interaction between the sodium ion and oxygens is properbly the origin of the good stability to the high temperature and the high humidity. $80SiO_2-20TiO_2$(mol%)의 무색투명한 비정질 박막을 현미경용 슬라이드 유리판과 사파이어 위에 tetraethyl orthosilicate와 titanium trichloride의 전구체 용액을 사용하여 스핀코팅방법으로 제조하였다. 코팅 후 $750^{\circ}C$에서 열처리된 박막은 높은 투과율과 낮은 반사율을 보였다. 슬라이드 유리판에 코팅한 $SiO_2-TiO_2$ 박막의 경우에 나트륨이온과 산소 간의 강한 상호작용에 의하여 고온과 높은 습도에서도 안정성이 우수하였다.

A Scenario-based Exposure Assessment on Polybrominated Diphyenyl Ethers (PBDEs)

Seulki Lee,Heeju Choi,Yongmu Kim,Da-In Kim,Haejung Yoon,Yun-Sook Kang 한국식품영양과학회 2021 한국식품영양과학회 학술대회발표집 Vol.2021 No.10

PBDEs are one of the flame retardants widely used in consumer products like plastics, textile, wire cable, electrical and electronic equipments. PBDEs are non-biodegradable, long distance movable, liphophilic substances wiith strong toxicity; these are registered Persistent Organic Pollutants at the Stockholm Convention. Since PBDEs detection in human was reported, there are some studies found that PBDEs in dust, air and even in food have been detected recently. In this study, we have assessed the exposure of PBDEs in Korean population. First, we identify exposure media and routes to make exposure scenario. To determine exposure parameter, we collected monitoring data in various media and selected data which are acceptable for criteria for data appropriateness. For other exposure paramenter, guidances in Korea were given priority, and if not available, foreign data were taken. Later on, we will identify a correlation between the estrimated exposure and human biomonitoring-based exposure and conclude whether the Korean are safe from PBDEs.

Preparation of SiO₂-TiO₂-M_xO_y ( M = Co, Cr or Cu ) Thin Films by the Chemical Solution Process

김상문,임용무,황규석,Kim, Sangmoon,Lim, Yongmu,Hwang, Kyuseog 한국안광학회 1998 한국안광학회지 Vol.3 No.1

$SiO_2-TiO_2-M_xO_y$ (M = Co, Cr or Cu)계의 비정질 박막을 현미경용 슬라이드 유리판 위에 전구체 용액을 스핀코팅방법으로 제조하였다. 전구체 용액은 tetraethyl orthosilicate, titanium trichloride, 그리고 코발트질산염, 크롬질산염, 구리질산염을 사용하여 합성하였다. X-선 회절분석 (${\theta}-2{\theta}$ scan)을 통하여 박막내에 $Co_3O_4$, $Cr_2O_3$, CuO 결정의 석출이 없는 비정질 박막임을 확인하였다. 코발트는 4면체배위의 $ Co^{2+}$로, 크롬은 4면체정배위의 $Cr^{6+}$로, 구리는 8면체배위의 $Cu^{2+}$로 존재하였다. 이 비정질박막의 표면에서 crack과 texture는 발견할 수 없었으며 파단면에서 박막악과 유리판 간의 계면은 균일한 조직을 보였다. Glass films of $SiO_2-TiO_2-M_xO_y$ (M = Co, Cr or Cu) have been prepared on soda-lime-silica slide glasses by the chemical solution method using a spin-coating technique. Commercially available tetraethyl orthosilicate, titanium trichloride, and cobalt-, chromium- and copper-nitrates were used as starting materials. No crystalline segregations of $Co_3O_4$, $Cr_2O_3$ and CuO were observed by X-ray diffraction ${\theta}-2{\theta}$ scans. From the optical transmission analysis, cobalt existed as $ Co^{2+}$ in tetrahedral coordination, chromium as $Cr^{6+}$ in tetrahedral symmetry and copper as $Cu^{2+}$ in octahedral coordination. Films with a crack-free and no texture exhibited homogeneous interfaces between the films and the substrates along the cross-section.

용액법에 의한 SiO₂-TiO₂-AgO계 박막의 제조 및 특성에 관한 연구

김상문,심문식,임용무,황규석,Kim, Sangmoon,Shim, Moon-Sik,Lim, Yongmu,Hwang, Kyuseog 한국안광학회 1998 한국안광학회지 Vol.3 No.1

$SiO_2-TiO_2-AgO$ 코팅박막을 졸-겔법으로 현미경용 슬라이드 유리판과 씰리콘 기판에 제조하였다. 이 박막의 열처리온도는 $500^{\circ}C$가 적절하였으며 5회 반복코팅한 박막의 두께는 310nm였다. AgO가 10mol% 첨가된 박막의 표면은 균일한 구조를 보였으나 첨가량이 많아질수록 박막의 표면에 pin hole과 AgO의 석출에 기인한 cluster를 보였다. 열처리온도의 증가에 따라 IR흡수의 정도가 점차 감소하였고, AgO 첨가량의 증가에 따라 반사율은 점차 감소하였으며 색상은 light yellow에서 무채색 쪽으로 점차 전이하였다. Coating films of $SiO_2-TiO_2-AgO$ have been prepared on soda-lime-silica slide glasses and single crystal silicon wafer by the sol-gel method using a spin-coating technique. Commercially available tetraethyl orthosilicate, titanium trichloride, and silver-nitrates were used as starting materials. The heat treatment temperature of this coating films was $500^{\circ}C$ properly, obtained from TG-DTA result. The films with thickness of 310 nm were prepared by 5 times coating. In the case of l0 mol% AgO, the film showed a crack-free and smooth surface, but the higher Ago content exhibited the more pin hole and the segregated cluster of AgO. The IR absorbance of the films decreased in the range of 400 nm to 700 nm with the increase of annealing temperature. And the reflectance of the coating films decreased and the color was changed light yellow to white yellow with the increase of Ago content.

A study on the determination of a Health based Guidance Value of Formaldehyde

Hyeonji Oh,Heeju Choi,Yongmu Kim,Seo Yun Kim,Jae-Hong Park,Haejung Yoon,Yun-Sook Kang 한국식품영양과학회 2021 한국식품영양과학회 학술대회발표집 Vol.2021 No.10

Formaldehyde can be exposed through various routes, including the environment such as air and water, food and cosmetics. Therefore, a risk assessment is necessary to identifiy and manage human health effect. This study aims to identify the relationship between formaldehyde exposure and adverse effects as a hazard characterization step in the risk assessment process and to establish and propose a Health based Guidance Value. In order to carry out ther research, we used some online databases to find scientific papers, reports and opinions published by other institutions. Data for dose-response assessment were selected and classified, as properties of toxicity, and then the most appropriate study for establishing Health based Guidance Value was finally decided. Til et al (1989), 2-years carcinogenicity study with rats, was the optimal toxicity data. As the toxicity endpoint, the Health based Guidance Value TDI 0.15 mg/kg bw/day was proposed by applying an uncertainty factor of 100(interspecies difference 10, intraspeices difference 10) to NOAEL 15 mg/kg bw/day for chronic atrophic gastritis, focal ulceration and glandular hyperplasia in the landular forestomach.