표준관입시험 및 시추공 정보를 이용한 국내 전단파속도 예측

허기석,곽동엽 한국지반공학회 2022 한국지반공학회논문집 Vol.38 No.8

The national ground survey database (GeoInfo) distributes numerous ground survey data nationwide. Many standard penetration test results exist in this database; however, the number of shear wave velocity (VS) data is small. Hence, to use abundant standard penetration test-N values to predict VS, this study proposed a new empirical N-VS relationship model using GeoInfo data. The proposed N-VS model is a single equation regardless of geological layer types; the layer type only specifies the upper limit of VS. To validate the proposed model, residual analysis was performed using a test dataset that was not used for the model development. Therefore, this study’s proposed model performed better than N-VS models from previous studies. Since the N-VS model in this study was developed using sufficient data from GeoInfo, we expect that it is the most applicable to GeoInfo dataset for VS prediction.

사이클 타임 단축을 위한 로터리 트랜스퍼 머신의 인덱스 테이블 구동부 설계에 관한 연구

허기석,박용우,김동선,류성기 한국기계가공학회 2022 한국기계가공학회지 Vol.21 No.8

This study focuses on the driving control design of an index, which is a key component of a rotary transfer machine that is effective in improving productivity and reducing manufacturing costs by shortening cycle time. Although various index studies have been conducted on the rotation of workpieces such as general-purpose machine tools and tilting indices, the development of an index for rotary transfer machines for transfer is insufficient. The index consists of a body, table, hydraulic cylinder, motor, reducer, and curved coupling. The torque of the table for driving was selected, and the angular velocity and torque pattern were simulated using the motor manufacturer's program. The specifications of the drive motor were determined based on the selected torque.

Selective metal detection by modified Rhodamine dyes supported on silica surface

허기석,정민영,도정윤 한국공업화학회 2016 한국공업화학회 연구논문 초록집 Vol.2016 No.0

Rhodamine fluorophore has attracted considerable interest from chemists on account of its strong emission. A lot of Rhodamine-derivatives have been developed for the detection of metal ions. For the selective recognition of a heavy metal ions, a sulfur-based functional group and oxygen-based functional group were considered during Rhodamine derivation. Metal coordination opens the ring of Rhodamine-derivative to change absorptive property. The ring opening and ring closure reactions are reversible and controllable with several coordination conditions. We examine the coordination effect according to the number of heteroatom (O, S) bound to Rhodamine. Heterocycles such as 1,3-dioxolane and 1,3-dithiolane are expected to form the better metal coordination kinetically, compared to the corresponding acyclic system. Fluorescent silica nanoparticles were prepared using NH2-rich silica surface.

Streptococcal Gangrene 2예(例)

허기석,강종봉,김영표 대한피부과학회 1980 대한피부과학회 학술발표대회집 Vol.32 No.1

Metal detection by Rhodamine dyes supported on silica surface

허기석,김치관,도정윤 한국공업화학회 2016 한국공업화학회 연구논문 초록집 Vol.2016 No.1

Rhodamine fluorophore has attracted considerable interest from chemists on account of its strong emission. A lot of Rhodamine-derivatives have been developed for the detection of metal ions(Cu²⁺, Hg²⁺, Al³⁺, Ca²⁺). For the selective recognition of a heavy metal ions, sulfur-based and oxygen-based functional groups were considered during Rhodamine derivation. Metal coordination opens the ring of Rhodamine derivative to change absorptive and emissive properties. The ring opening and ring closure reactions are reversible depending on metal species and their concentration. We measured complex constants of Rhodamine and metal ions and compared according to the number of heteroatom (O, S) bound to Rhodamine. Rhodamine hydrazones with several sulfur groups exhibited a selective response to Hg²⁺. Fluorescent silica nanoparticles were prepared through covalent binding of the Rhodamine to NH₂-rich silica. The metal binding of silica particles viewing fluorescence is discussed.

Dependence of the Structural and Electrical Properties of Co-Sputtered Zn-Doped ITO Thin Films on the Composition and Oxygen Partial Pressure

허기석,김은미 한국세라믹학회 2013 한국세라믹학회지 Vol.50 No.4

Zn-In-Sn-O films were prepared at room temperature by combinatorial RF-magnetron co-sputtering system. The cationic contents of the films were varied using a compositionally combinatorial technique. The effects of the oxygen partial pressure and film compositionon the structural and electrical properties were investigated. The Zn-In-Sn-O films deposited at Ar gas atmosphere showed an amorphous phaseirrespective of the film composition. However, the amorphous Zn-In-Sn-O films with a Zn content below 30.0 at% were converted into a bixbyite type-ITO polycrystalline phase with an increase in the oxygen partial pressure. The resistivity, carrier concentration, and Hall mobility were strongly affected by the oxygen partial pressure and chemical composition of the film. At sufficiently high carrier densities above 5 × 1018 cm−3, the conduction behavior of amorphous Zn-In-Sn-O film changes from thermally activated to degenerate band conduction accompanied with high mobility.

최근(最近) 10여년간(餘年間)의 외래(外來) 라환자(癩患者)의 임상적(臨床的) 관찰(觀察)

허기석,이재승,전인기,김영표 대한피부과학회 1979 대한피부과학회 학술발표대회집 Vol.31 No.2

최근(最近) 10년간(年間)의 피부과(皮膚科) 외래환자(外來患者)에 대(對)한 분석(分析)

허기석,최유섭,김윤섭,강종봉 대한피부과학회 1981 대한피부과학회 학술발표대회집 Vol.33 No.2

인터넷을 활용한 영어 읽기: 한국 중학생 학습 사례 연구

허기석 ( Ki Seok Heo ) 한국중등영어교육학회 2010 중등영어교육 Vol.3 No.1

The purpose of this study is to examine whether learning reading in English using the Internet is effective for Korean middle school students. A 4-week reading program was developed and taught through an Internet homepage. A total of 26 students participated in pre-, while-, and post-reading activities with five different types of reading comprehension questions; main idea, reference, details, sentence completion, and inference. The effect of learning through the Internet was analyzed by student questionnaires and reading comprehension tests that were conducted before and after the study. Almost all the students improved in their interest in learning reading and found the use of Internet quite useful probably thanks to diverse use of audio-visual materials, active participation through group works and interactive search of information on the Internet. The posttest result also showed significant improvement when compared to that of the pretest regardless of the question types, students`` pretest scores, overall English proficiency level, and their gender. Based on these results, the Internet-mediated reading program incorporated in this study seemed to have positive effect on the development of young EFL learner``s reading skills and attitude. The Internet is now a part of daily work for most elementary and middle school students in Korea. They have quick access to vast amount of information and their chance of communicating with native English speakers through the Internet is also on the rise. Therefore, if on-line reading materials are used more actively and suitably in classrooms, it could make a very efficient resource for many EFL students.

고리형 황화물을 포함하는 폴리아크릴레이트 합성과 설폭사이드 및 설폰 변환을 통한 굴절률 변화

허기석(Gisuk Heo),김새미(Saimi Kim),도정윤(Jung Yun Do) 한국고분자학회 2016 폴리머 Vol.40 No.3

황을 포함하는 고리형 아크릴레이트 단분자를 사용하여 고굴절률의 공중합 아크릴고분자 4종을 합성하였다. 황을 포함한 7-각 고리, 1,3-dithiane, 1,3-dithiolane 유도체를 사용하여 4가지의 아크릴 단분자를 합성하였고, 이를 methyl methacrylate(MMA)와 중량비로 3:7의 공중합고분자를 합성하였다. 오존(O₃)과 3-chloroperoxybenzoic acid (m-CPBA)를 사용하여 고분자에 포함된 황을 산화시켜 각각 SO와 SO₂를 갖는 고분자를 얻었다. 적외선 흡수 분광법(FTIR)과 수소핵자기공명분광(1H NMR) 분석을 통해 이러한 산화반응이 선택적으로 잘 진행되었음을 확인하였다. 합성된 고분자에 포함된 황의 함량에 따라 굴절률이 증가되는 것을 관찰하였다. 황이 SO로 산화되었을 때는 고분자의 굴절률이 증가하였고 SO₂로 산화되었을 때는 크게 감소하였다. SO₂를 갖는 단분자로 합성된 고분자와, 고분자의 산화로 SO₂ 를 갖는 고분자가 서로 유사한 성질을 보임으로써 고분자에 존재하는 황이 대부분 산화되었음을 확인하였다. 황산화 반응을 통해 고분자의 Abbe number는 증가되었다. 파장에 따른 굴절률을 계산하였고 산화반응을 통한 굴절률 변화가 모든 파장에 대해 유사하게 일어났음을 확인하였다. Polyacrylates with pending alkylsulfur groups were prepared to examine the changes in refractive index (RI) induced by sulfur oxidation. Four methacrylate monomers having cyclic alkylsulfur groups, such as 1,3-dithiane and 1,3- dithiolane derivatives, and 3,6-dithiacycloheptanol were developed. The monomers were copolymerized with methyl methacrylate through a radical polymerization. Oxidation of the prepared sulfur-polymers by O₃ and 3-chloroperoxybenzoic acid led to the formation of the corresponding SO and SO₂-polymers, respectively. The selective transformation of sulfur occurred completely and confirmed by FTIR and 1H NMR analysis. The RI of the polymer increased and decreased due to the formation of SO and SO₂, respectively. The SO₂-polymer exhibited a RI comparable to a polymer that was prepared using a sulfone-monomer. The Abbe number of the polymer increased after oxidation. The RI dispersion over various wavelengths was compared before and after oxidation.