혼합용매법에 의한 Mullite 전미분체 생성기구에 관한 연구

황운연,이정운,박형상,김용렬,구기갑 한국화학공학회 2003 Korean Chemical Engineering Research(HWAHAK KONGHA Vol.41 No.4

Si-와 Al-알콕시드의 반응속도 차이를 조절하기 위한 부분 가수분해법과 입자 형태를 제조하기 위한 혼합용매법을 이용하여 구형의 미세한 mullite 전미분체를 제조하였다. Mie 이론을 적용시켜 반응시간에 따른 반응용액의 탁도 및 입자 수밀도의 변화를 측정하여 혼합용매법에 의한 입자 생성기구에 대하여 고찰하였다. 알콕시드와 옥탄올 용액에 아세토니트릴을 첨가하면 알콕시드의 용해도가 낮아지고 따라서 알콕시드의 일부가 액적을 형성하며, 액적은 안정화제 (HPC)에 의하여 구형을 유지하게 된다. 그리고 가수분해 및 축합중합 반응에 의하여 액적의 입자 크기는 감소하며, 동시에 혼합용액에 용해되어 있던 알콕시의 가수 분해 및 축합중합 반응에 의하여 미세 입자가 생성된다. 액적형태로 생성된 큰 입자와 미세 입자의 응집에 의하여 최종 입자가 생성되었다. In this study, spherical fine pre-mullite particles were prepared by partial hydrolysis method to control the reaction rate difference of two alkoxides, and by mixed solvent method to control the particle shape. Based on the adaptation of Mie theory, the formation mechanism of pre-mullite particle in alkoxide-octanol-acetonitile system has been investigated by measuring of the turbidity of solution, the number density and the size of the particles during the reaction. As the acetonitrile was added in the alkoxide-octanol solution, the solubility of the alkoxide decreased. A part of alkoxide was segregated from solution in the form of droplets. whereas the rest of the alkoxide existed as dissolved state in octanol. The droplets are stabilized with stabilizer (HPC). In the next step. hydrolysis and condensation reactions of the alkoxide droplets decrease the size of droplets and, at the same time, fine particles are formed from the alkoxide dissolved in octanol. Subsequently, the final particles are produced by aggregation between the large particles through the droplet form and the fine particles.

사춘기전 Ⅰ,Ⅱ급 부정교합 아동의 기도 면적, 혀의 위치와 안면 형태에 관한 연구

황용인,이규홍,이기준,김상철,조형준,천세환,박양호 대한치과교정학회 2008 대한치과교정학회지 Vol.38 No.2

본 연구는 사춘기 성장 이전의 I, II급 부정교합을 갖는 아동 환자들의 측모 두부 규격 방사선사진을 이용하여 두개 안면 형태를 조사하고 이들과 혀의 위치 및 면적, 기도의 면적과의 관계를 조사하여 비인두 기도 및 혀의 형태가 악골 및 부정 교합의 형태에 미치는 영향을 알아보았다. 9 - 11세의 교정환자 76명을 대상으로 측모 두부 규격 방사선사진상 ANB difference를 기준으로 대조군(I급 부정교합군: 0 ≤ ANB difference < 4.0)과 실험군(II급 부정교합군: ANB difference ≥ 4.0)으로 분류하였다. 혀 면적, 혀와 구개 사이의 면적, 비인두 기도 면적과 두개안면형태 항목을 측정하고 비교하여 다음과 같은 결과를 얻었다. 혀 면적, 혀와 구개 사이의 면적, 비인두 기도 면적은 II급 부정교합군과 I급 부정교합군 간에 유의한 차이를 보이지 않았다. Hyperdivergent안면 형태일수록 비인두 기도 면적이 좁았다. 안모의 전후방 수직 길이가 길수록 혀의 면적이 넓었고, 전안면 고경이 길수록 혀는 하방위치 하였다. 비인두기도 면적이 좁을수록 혀의 면적도 좁아졌다. 이상의 연구 결과 혀의 면적과 위치, 비인두 기도의 면적은 I급, II급 부정교합 간에 차이를 보이지 않으며 hyperdivergent 안면 형태 및 안모의 전후방 수직 길이와 관련이 있는 것으로 사료된다. Objective: This study examined the craniofacial morphology of young patients in their prepubertal stage showing class I, II malocclusion, by analyzing lateral cephalograms, and analyzed its relationship with tongue position, tongue space, and airway space in order to ascertain the effects of nasopharyngeal airway and tongue morphology on the form of the malocclusion. Methods: Seventy-six patients aging from 9 to 11 were divided into two groups depending on the ANB difference on the lateral cephalogram: Experimental grouP (CI II malocclusion group) showing 0 ≤ ANB difference < 4.0; Control group (CI I malocclusion group) showing 0 ≤ ANB difference < 4.0. The tongue space, space between palate and tongue, nasopharyngeal airway space and craniofacial morphology were compared between the two groups. Results: Tongue space, Palate-tongue space, nasopharyngeal airway space showed no significant differences between class I and class II malocclusion groups. Hyperdivergent faces were associated with smaller nasopharyngeal airway space. Longer anterior facial height and posterior facial height were associated with larger tongue space, and greater anterior facial height were associated with lower tongue position, Smaller nasopharyngeal airway space showed smaller tongue space. Conclusions: Tongue space and nasopharyngeal airway space showed no significant differences between class I malocclusion group and class II malocclusion group. Only anterior facial height and posterior facial height had an influence on tongue space and nasopharyngeal airway space.

TOD형 개발 촉진을 위한 통합교통서비스 지표의 개발

황기연(Hwang Kee Yeon),신상영(Shin Sang Young),조용학(Cho Yong Hak),손기민(Sohn Kee Min) 대한토목학회 2008 대한토목학회논문집 D Vol.28 No.1D

최근 서울시는 TOD 기법을 활용하여 도심을 재활성화하기 위한 대규모 사업을 추진하고 있다. 그런데 TOD형 개발은 고밀개발을 전제로 하기 때문에 교통혼잡이나 환경의 질에 영향을 끼친다. 본 논문의 목적은 도로 뿐 아니라 버스, 지하철 등의 용량을 함께 고려한 통합교통서비스지표를 개발하여 TOD 개발을 촉진하는데 있다. 이를 위해 외국사례를 검토하고, 새로운 통합교통서비스 지표를 개발하고 이를 활용하여 서울시 도심에서 TOD형 고밀개발이 일어났을 때 교통부분의 기대효과를 분석하였다. 본 연구에서 개발한 통합교통서비스지표는 승용차, 택시, 버스로 구성된 도로서비스환경지표와, 지하철서비스환경 지표로 구성되며, 두 개의 지표를 통합하는 방법은 각 교통존별 서비스환경에 각 죤별 수단분담률로 가중평균해서 계산하되, 각 수단분담률의 합은 1로 하였다. 이러한 통합교통서비스환경(ITLOS: Integrated Transportation Level Of Service)의 수치는 0에서 1사이의 값을 가지게 되며, 0에 가까울수록 개발에 필요한 교통여건이 좋은 것으로 해석된다. 본 연구에서 도심고밀개발에 따른 기대효과를 분석하기 위해 대중교통과 도로교통을 동시에 고려한 통합교통서비스지표와 도로 교통서비스 수준만을 고려하는 통행속도 지표를 활용했다. 두 지표 모두 도심 고밀 개발 시 교통서비스 수준은 악화되는 것으로 나타났고 서울시 전체의 교통서비스 수준은 개선되는 것으로 분석되었다. 하지만 통합교통서비스 지표를 사용할 경우 비율적으로 도심교통상황의 악화 정도는 평균속도지표의 경우에 비해 낮게 나타났고, 반면 서울시 전체적인 개선폭은 비율적으로 상당히 높게 분석되었다. Recently, the Seoul Metropolitan Government (SMG) bas initiated several urban redevelopment projects to revitalize the downtown well equipped for transit oriented development (TOD). Since, TOD should incur higher density development in our context, it has negative impacts on travel patterns, congestion, and urban environmental quality. The purpose of this study is to develop new transportation service index which can facilitate higher density TOD. This study includes relevant foreign case studies, the development of multimodal transportation index, and the impact analysis of TOD when it is applied in the downtown Seoul. In chapter Ⅲ, it developed a so-called ITLOS, new multimodal transportation service index which shows the possibility of accommodating further development by integrating roadway service index with public transportation service index. The study sets ten policy scenarios by varying densities, and run the Seoul Congestion Management Model (SECOMM) to estimate the sustainable transportation impacts of TOD in the downtown. Travel speed index that only represents the availability of road capacity for development reveal that higher density development in the downtown can deteriorate traffic congestion while improving region-wide transportation level of service in Seoul. Also, it is proved that higher density development is more feasible when using ITLOS as the index because it considers not only available road capacity but subway capacity in the analysis area.

Predictors for progression in immunoglobulin A nephropathy with significant proteinuria

HWANG, HYEON SEOK,KIM, BYUNG SOO,SHIN, YOUNG SHIN,YOON, HYE EUN,SONG, JOON CHANG,CHOI, BUM SOON,PARK, CHEOL WHEE,YANG, CHUL WOO,KIM, YONG SOO,BANG, BYUNG KEE Blackwell Publishing Asia 2010 Nephrology Vol.15 No.2

<P>ABSTRACT:</P><P>Aim: </P><P>Proteinuria is a primary factor requiring treatment in immunoglobulin (Ig)A nephropathy. The purpose of this study was to assess the relevance of treatment response and relapse of proteinuria with renal function decline.</P><P>Methods: </P><P>One hundred and twenty-five biopsy-proven primary IgA nephropathy patients who had more than 1.0 g/day proteinuria at the first assessment were studied. All patients underwent anti-proteinuric treatment, and the association of the rate of renal function decline with treatment responsiveness, clinical and laboratory data was investigated.</P><P>Results: </P><P>The treatment response of the patients was: 30.4% complete response (<0.3 g/day proteinuria), 32.8% partial response (0.3–1.0 g/day), 23.2% minimal response (decrement but not reduced to <1 g/day) and 13.6% no response (no decrement of proteinuria). The slope of renal function decline (−1.06 <I>vs</I>−1.24 mL/min per 1.73 m<SUP>2</SUP>/year, <I>P</I> = 0.580) was comparable between complete and partial response groups, but they were slower than those of minimal or non-response groups (<I>P</I> < 0.001). In multivariate analysis including other parameters, mean arterial pressure (MAP; &bgr; = –0.240, <I>P</I> = 0.004) during follow up, minimal (&bgr; = –0.393, <I>P</I> < 0.001) and non-response (&bgr; = –0.403, <I>P</I> < 0.001) were significant predictors. In further investigation of complete and partial response groups, MAP (&bgr; = –0.332, <I>P</I> = 0.001) and relapse of proteinuria (&bgr; = –0.329, <I>P</I> = 0.001) were independently associated with slope of renal decline.</P><P>Conclusion: </P><P>Achievement of less than 1.0 g/day proteinuria and MAP were important for limiting the loss of renal function, and relapse of proteinuria should be closely monitored in proteinuric IgA nephropathy.</P>

Biological control of sciarid fly, Lycoriella mali (Diptera: Sciaridae) using Steinernema carpocapsae in button mushroom cultivation house

Yong-Seok Choi,Hwa-Young Seo,In-Su Hwang,Deog-Kee Park 한국농약과학회 2018 한국농약과학회 학술발표대회 논문집 Vol.2018 No.10

Distribution of Metcalfa pruinosa (Hemiptera: Flatidae) in Chungnam proince and host preference of its nymphs

Yong-Seok Choi,Hwa-Young Seo,In-Su Hwang,Deog-Kee Park 한국농약과학회 2018 한국농약과학회 학술발표대회 논문집 Vol.2018 No.10

DFT Study for Substitution Patterns of C₂₀H₁₈X₂ Regioisomers (X = F, Cl, Br, or OH)

Hwang, Yong-Gyoo,Lee, Seol,Lee, Kee-H. Korean Chemical Society 2012 Bulletin of the Korean Chemical Society Vol.33 No.2

We used the hybrid density-functional (B3LYP/6-31G(d,p)) method to analyze the substitution patterns of $C_{20}H_{18}X_2$ derivatives (X = F, Cl, Br, or OH) obtained as disubstituted $C_{20}H_{20}$ cages. Our results suggest that the cis-1 regioisomers (1,2-dihalo derivatives) are less stable than the trans-1 regioisomers (1,20-dihalo derivatives), whereas in the case of the dihydroxy derivatives, the cis-1 regioisomer is more stable than the trans-1 regioisomer. This implies that in the dihalo-induced strain cages of $C_{20}H_{18}X_2$, the strain effect would affect the relative energies, while in the dihydroxide, the hydrogen bonds have a stronger effect on the relative energies in cis-1 regioisomer than the strain effect do. Thus this supports the experimental result in which the bisvicinal tetrol was of particular preparative-synthetic interest as a substitute for the lacking bisvicinal tetrabromide. Further, the topologies of the HOMO and LUMO characteristics of all $C_{20}H_{18}Cl_2$ and $C_{20}H_{18}Br_2$ regioisomers with the same symmetry are same, but they are different from those of $C_{20}H_{18}F_2$ and $C_{20}H_{18}(OH)_2$. This indicates that the five regioisomers of each $C_{20}H_{20}$ disubstituted derivative will have an entirely different set of characteristic chemical reactions.

Plasmonic stop band formation in a metal–insulator–metal ring with a narrow gap

Hwang, Yongsop,Kim, Jae-Eun,Park, Hae Yong,Kee, Chul-Sik IOP Publishing 2011 Journal of optics Vol.13 No.7

<P>Using finite-difference time-domain simulations it is shown that a metal–insulator–metal (MIM) ring with a narrow gap exhibits plasmonic stop bands (PLSBs) in a similar way that a microstrip ring with a narrow gap exhibits photonic stop bands. A narrow gap created in the middle of the upper half of a regular MIM ring causes plasmonic fields to experience multiple reflections at the discontinuity introduced by the gap, which results in the formation of PLSBs. The PLSBs appear as transmission dips around the resonant frequencies of the isolated MIM ring with the narrow gap. The centre frequency and the range of PLSBs are shown to be controllable by varying the width of the narrow gap. The proposed design for a MIM ring in which PLSBs exist is expected to reduce the size of the plasmonic devices.</P>

Occurrence and distribution of weed species on horticulture fields in Chungnam province of Korea

Hwang, Ki Seon,Eom, Min Yong,Park, Su Hyuk,Won, Ok Jae,Lee, In Yong,Park, Kee Woong The Ecological Society of Korea 2015 Journal of Ecology and Environment Vol.38 No.3

A survey of weed occurrence was conducted to identify problematic weed species in a horticultural crop field to get basic information for effective weed control. Surveys of weed species occurring in horticultural crop fields (garlic, onion, red pepper and Chinese cabbage) were conducted in Chungnam province of Korea from April to October in 2014. A total of 516 sites of the 17 regions were identified as having 114 weed species belonging to 32 families. The most dominant weed species in the horticultural crop fields were Chenopodium album var. centrorubrum (8.83%), followed by Digitaria ciliaris (5.71%), Conyza canadensis (5.46%) and Capsella bursa-pastoris (4.67%). Specifically, as a result of this study, the occurrence of 35 species of exotic weeds, such as Chenopodium album and Taraxacum officinale, were confirmed. Almost 68% of the investigation sites was determined under dominance value 1 (range of cover < 10; numerous individuals) by Braun-Branquet cover-abundance scale, indicating a proper weed control in horticultural crop field. As a result of scientific and technological advances, an improved cultivation method is changing the weed occurrence in agricultural land. Additional research needs to be undertaken for the development of weed control methods through such periodic monitoring of occurrence of weeds.

Belt Source and In-Line Manufacturing Equipment for Very Large-Size AMOLED

Hwang, Chang-Hun,Kim, Yong-Ki,Lee, Tae-Hee,Yu, Sin-Jae,Kim, Sung-Su,Shin, Kee-Hyun,Ju, Sung-Hoo,Kwon, Jang-Hyuk The Korean Infomation Display Society 2006 Journal of information display Vol.7 No.4

The inline manufacturing equipment using a combination of the belt source and LPS source which is innovatively designed is introduced for the large-size AMOLED. The features of the inline system include 60sec TACT time, 19 numbers of chambers, non-substrate bending and easy application to very thin TFT substrates for the $4^{th}$ - $8^{th}$ Generation AMOLEDs.