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황희진,신기일,Hwang, Hee-Jin,Shin, Key-Il 한국통계학회 2009 응용통계연구 Vol.22 No.2
국내외적으로 지역통계에 관한 관심이 높아지고 있으며 이와 관련하여 소지역 추정에 관한 많은 연구가 진행되고 있다. 소지역 추정에 사용되는 추정량의 대부분은 MSE(moan squared error)를 최소화하여 얻어진다 (Rao, 2003). 최근 황희진과 신기일 (2008)은 MSPE(mean squared percentage error)를 최소화하는 추정량을 사용한 소지역 추정법을 제안하였다. 본 논문에서는 노동통계 중 지청별 일인당 평균 임금총액 추정에 황희진과 신기일 (2008)이 제안한 방법을 적용하여 보았으며 2007년 매월 노동통계 자료를 이용하여 기존의 MSE를 최소화 하여 얻어진 여러 추정량과 우수성을 비교해 보았다. 또한 노동통계를 위 한 소지역 추정의 실제 사용 가능성을 살펴보았다. Many researches have been devoted to the small area estimation related with the area level statistics. Almost all of the small area estimation methods are derived based on minimization of mean squared error(MSE). Recently Hwang and Shin (2008) suggested an alternative small area estimation method by minimizing mean squared percentage error. In this paper we apply this small area estimation method to the labor statistics, especially monthly wages by a branch area of labor department. The Monthly Labor Survey data (2007) is used for analysis and comparison of these methods.
황희진,Sunhui Han,전상옥,서조은,Dong-Ho Oh,Seong-Wan Cho,최영욱,이상길 대한화학회 2014 Bulletin of the Korean Chemical Society Vol.35 No.8
For the present study, rhEGF was encapsulated into solid lipid nanoparticles (SLNs). The SLNs were prepared by the W1/O/W2 double emulsification method combined with the high pressure homogenization method and the physical properties such as particle size, zeta-potential and encapsulation efficiency were measured. The overall particle morphology of SLNs was investigated using a transmission electron microscopy (TEM). The percutaneous skin permeation and accumulation property of rhEGF was evaluated using Franz diffusion cell system along with confocal laser scanning microscopy (CLSM). The mean particle size of rhEGF-loaded SLNs was 104.00 ± 3.99 nm and the zeta-potential value was in the range of −36.99 ± 0.54 mV, providing a good colloidal stability. The TEM image revealed a spherical shape of SLNs about 100 nm and the encapsulation efficiency was 18.47 ± 0.22%. The skin accumulation of rhEGF was enhanced by SLNs. CLSM image analysis provided that the rhEGF rat skin accumulation is facilitated by an entry of SLNs through the pores of skin.
Low-Z particle EPMA 단일입자 분석법을 이용한 지하철 승강장에서 미세입자 특징 분석
황희진,오미정,강선이,김혜경,노철언 한국대기환경학회 2005 한국대기환경학회지 Vol.21 No.6
A single particle analytical technique, named low-Zparticle electron probe X-ray microanalysis (EPMA), wasapplied to characterize samples collected at a subway station and ambient samples in Seoul. According to theirchemical composition, many distinctive particle types were identied. For samples collected at the subway stationplatform, the major chemical species are carbon-rich, organic, aluminosilicates (AlSi), AlSi/C, AlSi/CaCO3,CaCO3, SiO2, and Fe2O3. For outdoor samples, carbon-rich, organic, AlSi, CaCO3, SiO2, NaNO3,(Na,Mg)NO3, Na(CO3,NO3,SO4), and (NH4)2SO4 high contents of Fe2O3, both in coarse and fine fractions, which come from brake block, subway train wheel,electric contact materials, etc. It is demonstrated that the single-particle characterization using this low-ZparticleEPMA technique provided detailed information on various types of chemical species in indoor and outdoor samples.
황희진,니암게렐 얄랄트,이정훈 한국지구과학회 2021 한국지구과학회지 Vol.42 No.4
Several studies investigating the behavior and environmental distribution of rare earth elements (REEs) have been reviewed to determine the geochemical processes that may affect their concentrations and fractionation patterns in groundwater and whether these elements can be used as tracers for groundwater-rock interactions and groundwater flow paths in small catchments. Inductively coupled plasma-mass spectrometry (ICP-MS), equipped with an ultrasonic nebulizer and active-film multiplier detector, is routinely used as an analytical technique to measure REEs in groundwater, facilitating the analysis of dissolved REE geochemistry. This review focuses on the distribution of REEs in groundwater and their application as tracers for groundwater geochemistry. Our review of existing literature suggests that REEs in ice cores can be used as effective tracers for atmospheric particles, aiding the identification of source regions.
소결과정에서 Fe_2O_3-CaO-Al_2O_3-SiO_2계로부터 Calcium-Ferrite 생성거동에 미치는 염기도의 영향
黃熙鎭,車榮宰,兪炳敦,韓晶煥,李始衡,許完旭 대한금속재료학회 2002 대한금속·재료학회지 Vol.40 No.5
The effect of the basicity on the formation behaviour of calcium ferrites was investigated in the sintering process of Fe_2O_3-CaO-Al_2O_3-SiO_2 system. In the system of Fe_2O_3-CaO-Al_2O_3, the mineral structure consists of iron oxide particles and matrix phase, which is likely to be CF(calcium ferrite). When SiO_2 is added into Fe_2O_3-CaO-Al_2O_3 system, the area fraction of CF decreases sharply. When the basicity(CaO/SiO_2) decreases below the unity, CF does not form, and the mineral structure is composed of iron oxide particles and the silicate slag. The iron oxide particles are mainly magnetite in the temperature range higher than 1300℃, while they consist of both magnetite and hematite at the temperatures below 1250℃. When SiO_2 is added into Fe_2O_3-CaO-Al_2O_3 system, the formation of hematite is promoted in the lower temperature range. The increase of SiO_2 content tends to change the composition of CF from hemi-CF to mono-CF. The solubility of solutes such as CaO, Al_2O_3 and SiO_2 in CF increase with the increase of SiO_2 content in the system.
Boron Nitride Nanofibers by the Electrospinning Technique
황희진,Nasser A. M. Barakat,Muzafar A. Kanjwal,Faheem A. Sheikh,김학용,M. F. Abadir 한국고분자학회 2010 Macromolecular Research Vol.18 No.6
An interesting boron nitride ceramic was introduced in nanofibrous form. Boron nitride nanofibers were prepared using a simple and cheap strategy. Calcination of poly(vinyl alcohol) electrospun nanofibers embedded with boron nitride nanoparticles resulted in a nanofibrous form. The electrospun nanofiber mats were prepared by electrospinning of a colloidal solution composed of an aqueous poly(vinyl alcohol) solution and boron nitride nanoparticles. Calcination of the obtained BN/PVA nanofiber mats in an argon atmosphere at 1,000 oC for 5 h resulted in boron nitride nanofibers. The boron nitride nanofibers showed a higher band gap than the nanoparticles; the latter showing a band gap of 2.75 eV. however, the nanofibrous shape enhanced the band gap to 4.52 eV.