• 한국전통조경학회지
• /
• 제39권4호
• /
• pp.99-110
• /
• 2021

본 연구는 신라왕경 경주, 고려 개경, 조선 한양, 조선후기 신도시로 조성된 수원 화성을 중심으로 우리나라의 역사도시에서 나타난 도시수체계의 구성방법이 지니는 특성을 파악해보고자하는 목적을 지니고 있다. 특히 도시입지, 도로, 도시시설 배치 등을 중심으로 도시골격구조와 연계하여 물길이 지니는 의미를 살펴보고 수체계의 구성형태에 대한 해석을 통하여 도시 내 수공간 경영에 투입되었던 기술적, 계획적 요소와 함께 도시구조와의 관계를 분석하였다. 연구대상지에서는 자연수계를 기반으로 부분적인 하천 정비와 인공수계를 도입하여 도시수체계가 구축되고 있다. 특히 물과 자연수계는 도시의 입지를 결정하는 핵심요소로 작용하고 있으며 도시구조와 도시발달과정, 도시구조와 밀접한 관계를 지니고 있음을 알 수 있다. 여기에는 지리적 관념과 어우러져 물이 지니는 상징적 의미와 더불어 치수, 이수 등의 관점에서 요구되는 현실적 수요가 중요한 배경으로 자리하고 있다. 물 공간과 관련된 다양한 수요에 대응하기 위하여 도시 형성·발달과정에서 물 공간을 경영하기 위한 다양한 계획적, 기술적 요소가 도입되었다. 연구대상지에 대한 분석을 통하여 도시형성·발달과정에서 도시수체계가 지니는 계획적 요소를 종합해보면 다음과 같이 요약된다. 첫째로 연구대상지로 선정된 신라왕경 경주, 고려 개경, 조선 한양, 수원 화성의 도시수체계를 구축하는 과정에는 배수, 재해를 고려한 치수의 관점이 공통적으로 작용하고 있지만 수체계의 구축방법이나 활용성에서는 차이를 나타내고 있다. 둘째로 물과 자연수계는 도시입지의 상징적 요소로서, 그리고 지리적 관념과 어우러진 도시 입지를 결정하고 도시의 좌향을 결정하는 핵심요소로 작용하고 있다. 셋째로 도시가 형성되기 이전의 자연수계는 지형여건과 어우러져 도시 형성·발달과정에서 구축되는 도시수체계의 구성형태를 결정하는 기반으로 작용하고 있다. 넷째로 자연수계를 기반으로 구축된 도시수체계는 자연물길과 계획적 인공수로가 결합되어 도시구조의 일부로서 위계별 수계의 활용성이 차이를 나타내고 있다. 다섯째로 도시수체계는 배수체계와 재해를 고려한 치수의 관점 이외에 도시용지의 확보, 도시시설 배치와 영역 확보, 기능지역 구성, 토지구획과 연계하여 계획적으로 구축되고 있다.

• 한국세라믹학회지
• /
• 제47권2호
• /
• pp.117-121
• /
• 2010

$SnO_2-(1-x)P_2O_5-xB_2O_3$ glass system were prepared by melt-quenching technique in the compositional series containing 50, 55 and 60 mol% of $SnO_2$. Local structure of the glasses was investigated by Raman and FT-IR measurements. A large glass-forming region was found at the phosphate side of the ternary system with homogeneous glasses containing up to 5~25 mol% of $B_2O_3$. According as content of $B_2O_3$ increases, theraml expansion coefficient of glass decreased but transition temperature and softening temperature increased. Because these phenomenon changed local structure of glass. According as content of $B_2O_3$ increases, quantity of bridging oxygen increased. Also, according as content of $SnO_2$ increases, confirmed that quantity of non-bridging oxygen increases.

• 전자공학회논문지D
• /
• 제34D권3호
• /
• pp.60-73
• /
• 1997

By introducing a compressive-strained quanternary InGaAsP quantum-wells instead of a conventional ternary InGaAs quantum-wells in 1.55.mu.m DFB-LD, the lasing performances canb e improved and the problems caused by the thickness non-uniformity and the compositional abruptness among the hetero-interpaces canb e relaxed. In this paper, we investigated an iptimum InGaAsP/InGaAsP multiple-quantum-well(MQW) structure as an active layer in a direct-modulated 1.55.mu. DFB-LD from the view point of threshold current, chirping charcteristics, and resonance frequency. The optimum compressive-strained MQW structure was revealed as InGaAsP/InGaAsP structure with strain amount of about 1.2%, number of wells $N_{w}$ of 7, well width $L_{w}$ of 58.agns.. The threshold current density J of 500A/c $m^{2}$, the linewidth enhancement factor a of 1.8, and differential resonance frequency of d $f_{r}$/d(I-I)$^{1}$2/=2GHz/(mA)$^{1}$2/(atI=2 $I_{th}$) were expected in 1.55.mu.m .gamma./4-shifted DFB-LD with the cavity length of 400.mu.m long and kL value of 1.25. These values are considerably improved ones compared to those of 1.55um DFB-LD with InGaAs/InGaAsP MQW which have enhancement factor and the resonance frequence frequency by the detuning of lasing wavelength and gain-peak wavelength. It was found that the linewidth enhancement factor of 20% and differential resonance frequency of 35% without the degradation of the threshold current density could be enhanced in the range of -15nm~-20nm detuning which can be realized by controlling the thickness and Incomposition of InGaAsP well. well.and Incomposition of InGaAsP well. well.

• 한국항공우주학회지
• /
• 제34권1호
• /
• pp.65-73
• /
• 2006

무인항공기는 엔진에서 연료의 연소, 배기관에서 고온의 연소 배기 가스등으로 인하여 많은 부분에 고온이 발생한다. 이는 전체 구조물의 안정성에 심각한 영향을 미칠 수 있는 사항이다. 경사기능재료는 고온의 환경에서 열에 저항하기 위해 한쪽 재료는 세라믹으로, 다른 쪽 재료는 가볍고 구조적 강성을 지닌 금속재료로 점차적으로 변화된 재료를 사용한 일종의 복합재료이다. 경사기능재료는 뛰어난 내열성을 가지는 특성으로 고온 상태에서 많이 사용된다. 이에 따라 본 논문에서는 경사기능재료를 무인항공기의 엔진 배기 덕트에 적용하여 열적 거동을 고찰하였고, 경사기능 층이 20개, 40개, 60개, 80개, 100개인 경사기능재료를 덕트 구조물에 적용하여 각각의 열 및 열응력 해석을 수행하여 비교 분석하였다. 또한, 경사기능재료를 사용한 고온 내열 배기 덕트의 크리프 해석을 수행하여 그 특성에 대해 고찰하였다.

• Architectural research
• /
• 제15권4호
• /
• pp.183-190
• /
• 2013

The 'one-day-shopping' concept that we experience today in a modern mega mall changed the propensity to consume compared to the past. The idea of a mega mall originated in the U.S. and the first suburban shopping malls as we know them today were built in the 1950s. The convenience of these malls had a great impact not only on consumers but also on the retail industry in general and the new mega mall idea has since spread around the world, with the largest ones located in China and Southeast Asia. Meanwhile, Korea had the fastest-growing economy during the last three decades and with that boom the compositional structure of domestic retail facilities became extremely diverse. Today, there are 36 new mega mall development plans to be completed before 2016, which represent a rapid and dynamic change in consumerism lifestyle in Korea. In this regard, this study will re-evaluate the first mega mall in Korea, the COEX Mall, and identify initial errors regarding its circulation plan and provide an ideal design strategy for future commercial mega malls based on literature review and comparison analysis.

• Bulletin of the Korean Chemical Society
• /
• 제33권3호
• /
• pp.855-861
• /
• 2012

A pioneering version of an on-line management system for high-energy molecules (MS-HEMs) was developed by the ADD and BMDRC in Korea. The current system can manage the physicochemical and explosive properties of virtual and existing HEMs. The on-line MS-HEMs consist of three main routines: management, calculation, and search. The management routine contains a user-friendly interface to store and manage molecular structures and other properties of the new HEMs. The calculation routine automatically calculates a number of compositional and topological molecular descriptors when a new HEM is stored in the MS-HEMs. Physical properties, such as the heat of formation and density, can also be calculated using group additivity methods. In addition, the calculation routine for the impact sensitivity can be used to obtain the safety nature of new HEMs. The impact sensitivity was estimated in a knowledge-based manner using in-house neural network code. The search routine enables general users to find an exact HEM and its properties by sketching a 2D chemical structure, or to retrieve HEMs and their properties by giving a range of properties. These on-line MS-HEMs are expected be powerful tool for deriving novel promising HEMs.

• 한국결정성장학회지
• /
• 제19권2호
• /
• pp.66-69
• /
• 2009

The compositional dependence of bismuth iron oxides and effect of La-substitutions in the structure of $BiFeO_3$ compounds were investigated, which compounds were synthesized by conventional ceramic processing. It is shown that some of bismuth iron oxides including $BiFeO_3$ show the narrow single phase region. The effect of La-doping in $BiFeO_3$ was presented as disappearance of many impurity phases of Bi-Fe-O compounds. The lower electrical resistivity was obtained as those compositions of Fe deficient region and La-doped $BiFeO_3$. The saturation magnetization of La-doped $BiFeO_3$ was increased with La content. The dielectric dispersion was also observed for those Bi-Fe-O compounds with Fe deficient and La-doped $BiFeO_3$ at low frequencies under 1 kHz.

• 한국재료학회지
• /
• 제12권8호
• /
• pp.661-668
• /
• 2002

A study was made to examine the electrical, compositional, structural and morphological properties of Ag thin films deposited by DC magnetron sputtering in $O_2$ atmosphere with deposition temperature from room temperature to 15$0^{\circ}C$ using in-line sputter system. The Ag films deposited at temperature above $100^{\circ}C$ in oxygen atmosphere gave a similar specific resistivity to and even lower oxygen content than those deposited using pure Ar sputter gas The Ag films deposited with pure Ar gas was mainly composed of crystallites with [111] preferred orientation, while, for those deposited in oxygen atmosphere, more than 50% of the volume was composed of crystallites with [100] orientation. The difference in the micro structure did not cause any difference in the specific resistivity of Ag films. The results showed that the transparent conducting oxide films and the Ag films could be processed sequentially in the same deposition chamber with careful control of deposition temperature, which might result in a cost reduction for constructing the large scale in-line deposition system.

• 약학회지
• /
• 제38권6호
• /
• pp.782-785
• /
• 1994

Some traditional herbal drugs have been used after processing to modify its activities. For example, roasted 'chiyu' (Sanguisorbae radix) has been used as antihemorrhagics while raw one used as anti-emetics. The composition of herbal drug is expected to be changed during this process. We tried to reveal the compositional difference between raw and roasted 'chiyu', and isolated the compounds which are changed in their contents. The structure of the isolated compounds were elucidated as pomolic acid and 3-O-acetyl pomolic acid. The contents of pomolic acid and 3-O-acetyl pomolic acid in raw 'chiyu' were ca. $4.5{\times}10^{-3}%$, $7.2{\times}10^{-4}%$, respectively, and in roasted 'chiyu' were ca. $7.3{\times}10^{-3}%$ and $1.1{\times}10^{-3}%$, respectively.

• The Korean Journal of Ceramics
• /
• 제5권3호
• /
• pp.224-229
• /
• 1999

The preparation and toughening of SiC-AIN solid solution from powder mixtures of $\beta$-SiC, AIN and $\alpha$-SiC by hot-pressing were studied in the 1870 to $2030^{\circ}C$ temperature range. The reaction of AIN and $\beta$-SiC(3C) powders causing transformation to the 2H(wurtzite) structure appeared to depend on hot-pressing temperatures and an additive of $\alpha$-SiC. For the composition of 49wt% SiC with 2 wt% $\alpha$-SiC and 47.5 wt% AIN47.5wt% SiC with 5 wt % $\alpha$-SiC at 203$0^{\circ}C$ for 1 h, th complete solid solutions with a single phase of 2H could be obtained. The appreciable amount of $\alpha$-SiC could develop the columnar inter-grains of 4H phase and the stable 2H phase with the relatively uniform composition and grain size distributions. The effect of $\alpha$-SiC on the phases present and compositional microstructures with columnar inter-grains was invetigated using X-ray diffraction, scanning electron microscopy and transmission electron microscopy. The fracture toughness and Vickers hardness of the hot-pressed solid solutions wre examined by the indentation-fracture-test method.