• Food Science of Animal Resources
• /
• v.31 no.6
• /
• pp.893-898
• /
• 2011

Milk contains a number of nutrients required for human growth and development, such as disaccharide lactose which is significantly contained in milk and dairy products. About two thirds of world populations are reportedly suffering from lactose intolerance after drinking milk. Lactose intolerance is defined as a maldigestion of lactose in the human intestine with typical symptoms of abdominal pains, bloating, and diarrhea. In this study, incidence of lactose intolerance has been investigated for the elementary school children for 1 year from July, 2010 to June, 2011. It is found that about 70% of the total elementary students have joined the school milk program. Out of 636 total students that participated in this study, 449 were from the metropolis, 85 from middle-sized city, and 102 from the small town including rural areas (small town/rural areas). For distributions of lactose intolerance, 154 students (24.2%) were found to be positive among the total 636 subjects. Based on the size of the city, the symptoms were the most prevalent for the students in the small town/rural areas at 31.4% (32/102), followed by 30.6% (26/85) in middle-sized city, and 21.4% (96/449) in the metropolis. On the other hand, gender had no significant effect on the incidence of lactose intolerance, shown those for boys and girls were 24.8% (77/310), 23.6% (77/326), respectively. Further research is needed to confirm the correct incidence of lactose intolerance symptoms as the frequency is significantly affected by subject's digestive functions including irritable bowel syndrome.

• Journal of Korean Vacuum Science & Technology
• /
• v.2 no.2
• /
• pp.92-96
• /
• 1998

Ferroelectric Bi-layered oxides SrBi2Ta2O9 (SBT) thin films have been deposited on Pt/Ti/SiO2/Si substrates using multi-target sputtering. Structure, composition, and electrical properties have been investigated on films. The SBT films were deposited with the various bismuth sputtering powers. The SBT films deposited with the bismuth sputtering power of 20 W have the most dense microstructure and the remanent polarization (Pr) of 9.2 ${\mu}$C/cm and the coercive field (Ec) of 43.8 kV/cm at an applied voltage of 5V. The SBT films deposited with the bismuth sputtering power of 20W showed a fatigue-free characteristics up to 1.0${\times}$1010 cycles under 5V bipolar pulse and a leakage current density of 2.0${\times}$10-8 A/$\textrm{cm}^2$ at 200 kV/cm.

• Applied Microscopy
• /
• v.29 no.1
• /
• pp.95-103
• /
• 1999

Microstructural observations on the pseudo-brookite $MgTi_2O_5$ and the similar type of $(In_{0.36}Zn_{1.09})Ti_2O_{5.64}$ were carried out using a top-entry HRTEM working at 200 kV. The modulated structures were found in $(In_{0.36}Zn_{1.09})Ti_2O_{5.64}$, however, not in $MgTi_2O_5$. The electron diffraction patterns of sublattice in $(In_{0.36}Zn_{1.09})Ti_2O_{5.64}$ are quite similar to those of pseudo-brookite $MgTi_2O_5$. but the complicated superlattice reflections are present in the diffraction patterns. Four types of modulations have been found. The periodicities for the modulated structure are found to be 3.63 nm, 0.79 nm and 0.64 nm along [220] direction, and 0.81 nm along [420] direction. The phase transition from the modulated structure to the unmodulated one was also observed in situ due to the electron beam irradiation reversibly. Further damage by the electron beam made the crystal to be fragmented into many small crystals with the formation of the voids at the kinks in ledged structure of the surface. The anisotropic arrangements of In and O atoms in $(In_{0.36}Zn_{1.09})Ti_2O_{5.64}$ might cause the compound to be unstable under the electron beam.

• Polymer(Korea)
• /
• v.29 no.4
• /
• pp.418-421
• /
• 2005

Three-dimensional (3D) microfabrication process using two-photon polymerization (TPP) is developed to fabricate the curved microstructures in a layer, which can be applied potentially to optical MEMS, nano/micro-devices, etc. A 3D curved structure can be expressed using the same height-contours that are defined by symbolic colors which consist of 14 colors. Then, the designed bitmap figure is transformed into a multi-exposure voxel matrix (MVM). In this work a multi-exposure voxel matrix scanning method is used to generate various heights of voxels according to each laser exposure time that is assigned to the symbolic colors. An objective lens with a numerical aperture of 1.25 is employed to enlarge the variation of a voxel height in the range of 1.2 to 6.4 um which can be controlled easily using the various exposure time. Though this work some 3D curved micro-shapes are fabricated directly to demonstrate the usefulness of the process without a laminating process that is generally required in a micro-stereolithography process.

• Korean Management Science Review
• /
• v.9 no.1
• /
• pp.93-118
• /
• 1992

This paper addresses the problem of locating a telephone switching center at new establishing city or town. There have been several studies on the location of telephone switching center at an existing telephone network to cope with the expanding subsciber's demand, in most of which only the economic factors were considered and was determined where the switching center is established in order to minimize the total cost. This paper, However, deals with the social factors as well as the economic ones. We develop a location model considered these two factors simultaneously by using a fuzzy approach. Finally, we apply the model to locate a new telephone switching center at the Haeundae where the Pusan City intends to construct a new town.

• Proceedings of the Acoustical Society of Korea Conference
• /
• spring
• /
• pp.213-216
• /
• 2004

본 연구에서는 복잡한 형상을 가진 음원으로부터 방사하는 음장을 등가음원법 (equivalent source method)을 이용하여 재구성한다. 일반적인 등가음원법의 기본 원리는 진동하는 물체의 표면 또는 내부에 등가음원을 분포시켜서 등가음원의 강도를 계산하는 방법이다. 각 등가음원의 강도는 음원의 경계 조건이나 측정된 음장 음압을 통해서 구할 수가 있으며 사용된 등가음원의 차수, 개수 그리고 위치 등은 고려되어야 할 중요한 변수들이다. 기존의 HELS (Helmholtz equation least square) 방법은 한 곳의 위치에 다양한 차수로 이루어진 등가음원을 사용하여 각 차수의 계수를 구하는 방법으로써 구형에 가까운 음원에 대해서 좋은 결과를 보이나 음장의 결과가 최대 차수의 선택에 따라서 큰 오차를 유발하는 문제점이 있다. 따라서 정규화 기법을 사용하여 음장을 재구성하기 위해 필요한 등가음원의 최적 차수를 구하고, 음원 내부에 최적 차수로 이루어진 등가음원을 여러 개의 점에 위치시켜서 재구성 정확도를 향상시켰다. 정규화된 등가음원법의 타당성 검증을 위하여 표면 일부가 진동하는 구에 대한 수치 해석 및 청소기 모델에 대한 음장 재구성 실험 을 수행하였다.

• Proceedings of the Acoustical Society of Korea Conference
• /
• spring
• /
• pp.297-300
• /
• 2004

Perforated elements are extensively used in mufflers for the intake and exhaust systems of various fluid machines. Perforated elements are usually exposed to grazing flow or cross flow. For analyzing performances of mufflers, the impedance of perforated elements with mean flow is very important. The impedance of perforates under both conditions are measured with different experimental setups. Even if there is no flow, the preceding experimental method for grazing flow shows different values with both theoretical ones and measured under cross flow setup. Using high-order analysis considering phase differences, the experimental method for grazing flow can be modified. The acoustical impedance of perforated impedance contains interaction effects between orifices. After correcting these effects, the measured impedance with grazing flow setup show similar results with both theoretical impedance and measured ones under cross flow setup.

• Proceedings of the Acoustical Society of Korea Conference
• /
• autumn
• /
• pp.309-312
• /
• 2004

본 연구에서는 매미가 소형이면서도 광대역의 소리를 낼 수 있는 원리가 무엇인지를 파악하고 이중 음향 발생 장치 제작에 적용할 수 있는 요소를 도출하였다. 매미의 발음기관에서 가장 중요한 부분은 복부 공명실과 진동판이다. 복부 공명실은 위상 반전형 인클로져 시스템으로 모델링 할 수 있으며, 진동판은 돔 형태의 박판으로 볼 수 있다. 근육에서 발생된 입력 신호는 진동판의 곡면에 의해 판에 좌굴을 일으켜 높은 음압의 소리를 발생시킨다. 발생된 소리는 복부를 통해 위상이 반전되어 특정 대역이 강조된다. 진동판의 가장 큰 특징은 곡면구조에 의한 비선형적인 출력이며 이를 통하여 가진 주파수와 상이한 주파수 성분들을 효과적으로 발생시키게 된다. 이러한 구조를 음향 발생장치로 활용하기 위하여 단순한 곡면판의 기하학적 파라미터 변화에 따른 출력 변화 경향을 관찰 하였으며, 이러한 원리를 활용한 음향 발생장치를 구성하였다.

• Proceedings of the Technology Innovation Conference
• /
• 2006.02a
• /
• pp.150-169
• /
• 2006

Science & Technology (S&T) personnel have played a major role to develop our country since S&T is the most important factor to increase national competitiveness in the 21st century. Therefore, it is very essential to increase the welfare of S&T personnel in order to increase national S&T and economic competitiveness. However, the welfare of S&T personnel has not been discussed sufficiently not only in academic research, but also in actual S&T policies. It has caused many. social problems (for example, avoiding fields of S&T of young generation, low social recognition of S&T community and so on). Under this background, this paper aims at investigating how to effectively improve S&T personnel's welfare. For this purpose, we deal with a theoretical review on the welfare of S&T personnel. After that, we will suggest 'Comprehensive Welfare Town for S&T Personnel' as a method of improving the welfare of S&T personnel.

• Journal of Korea Technology Innovation Society
• /
• v.2 no.1
• /
• pp.58-73
• /
• 1999

The venture firms originating from the government-financed research institutes of Taeduk Science Town play a dominant role in Taejon. Those venture fm have the following characteristics. First, they are innovative in the growth stage, although not so innovative in the beginning stage. Second, they still largely depend on the domestic market because of their import-substitution strategy. Third, they mostly lack administrative capabilities. Finally, the infrastructure of venture firms is not good in spite of many supporting government policies. The efficient management of the existing business incubators, the establishment of special venture capital, and continuous supports by the incubating organizations should be warranted to encourage the spin-offs from the government- financed research institutes.