본 연구는 지역별, 학교별, 계절별 고등학교 급식 식단의 미생물학적 안전성 관련 주요 영향 인자를 도출하고자 식단 데이터를 수집하고 요인을 분석하여 향후 안전관리 방향을 설정하기 위해 실시하였다. 급식식단 중 PHF(Potentially Hazardous Food) 해당여부, 사용빈도가 높은 엽경채류, 식단 조리방법에 관하여 빈도 분석과 다중대응분석(Multiple correspondence analysis, MCA)을 실시하였다. 중부지역과 남부지역의 각각 3개 고 교, 총 6개 고등학교의 3, 6, 9, 12월 제공된 총 1,945개 식단의 빈도분석 결과, PHF에 해당하는 식단은 데친 나 물류, 샐러드, 해조류, 닭튀김 등이 사용빈도가 높았다. 조리방법은 가열 여부에 따라 단순 가열, 단순 비가열, 혼합 여부에 따라 가열한 식재료와 가열한 식재료의 혼합, 비가열한 식재료와 비가열한 식재료의 혼합, 가열한 식재료와 비가열한 식재료의 혼합으로 구분하였는데, PHF 제품 내 단순 비가열과 가열한 식재료와 비가열한 식재료의 혼합과 같은 메뉴 유형도 33.1% 수준으로 나타났다. 사용빈도가 높은 엽경채류는 시금치, 부추, 상추, 양배추, 깻잎, 양상추, 치커리, 파, 브로콜리 순서로 나타났다. 전체 식단 중 사용빈도가 높은 엽경채류 14종 370개의 데 이터에 대한 MCA 결과 PHF에 해당하는 엽경채류에는 양상추, 청경채가, Non-PHF에 해당하는 엽경채류에는 브로콜리, 양배추, 치커리, 깻잎이 주로 사용되었다. 지역별로는 중부지역에서는 마늘쫑과 시금치가, 남부지역에는 미나리 사용빈도가 상대적으로 높았다. 향후 단체급식에서 농산물의 미생물학적 안전성을 높일수 있도록 생산단계에서 오염원 차단(GAP 인증), 저감 및 세척 공정 개발, 식재료별 조리방법에 따른 메뉴 데이터 베이스화, 미생물학적 안전성이 확보되는 조리방법을 활용한 식단 개발 및 검증이 필요하다.

PURPOSES: A tack coat has been utilized to increase the bond performance between the surface layer and base course (intermediate course) at various road pavement sites. This is similarly true in other nations. Based on this connection, the objective of the present study is to evaluate the properties of hot mix asphalt (HMA) mixtures with an RSC-4 or BD-Coat and determine the application rate of the tack coat. METHODS: The HMA specimens were manufactured using superpave gyratory compaction. The HMA mixtures were composed of a 5-cm thick surface layer and a 10-cm thick base course. An impact hammer resonance test (IHRT) and a static load shear test were conducted to evaluate the performance of the HMA mixtures with a tack coat. From these tests, the dynamic moduli related to the high-frequency resistance and interlayer shear strength (ISS) of HMA could be obtained. RESULTS: The results of the dynamic moduli of HMA are discussed based on the resonance frequency (RF). To check the accuracy of the IHRT, we conducted a coherence analysis. A direct shear test using the application of a static load test was carried out to evaluate the interlayer shear strength (ISS) of HMA. CONCLUSIONS: The maximum ISS was demonstrated at an RSC-4 application rate of 462 gsm, and the maximum dynamic modulus was demonstrated at an RSC-4 application rate of 306 gsm. By averaging the results of the ISS, the maximum ISS values were obtained when a BD-Coat application rate of 602 gsm was applied.

This study investigated the magnetic properties and frequency dispersion of complex permeability of Ni-Zn-Co ferrites used for magnetic shielding in near field communication (NFC) system. The sintered specimens of (Ni0.7Zn0.3)1-xCoxFe2O4 composition were prepared by the conventional ceramic processing. The coercive force and saturation magnetization were measured by vibrating sample magnetometer. The complex permeability was measured by RF impedance analyzer in the range of 1 MHz~1.8 GHz. The coercive force increased and saturation magnetization decreased with increasing the Co substitution. The real and imaginary parts of complex permeability decreased and the resonance frequency increased with Co substitution, which was attributed to the increase in crystal anisotropy field and reduction in saturation magnetization. The effect of Co substitution could be found in reducing the magnetic loss to nearly zero at the operating frequency of NFC (13.56 MHz).

We divided the sample into four groups by temperature regimes and comparing the Lethal effect after exposure to high room temperatures for 50~58 days. After inoculating Cnidium officinale Makino with Tribolium castaneum Herbst, the storage insects of medicinal herbs, was 20 respectively. The results of treating cut Cninium officinale Makino are listed below. Survival rate of group A by exposure of 5 times at 35~36.5℃ is less than 7.5%. Survival rate of group C by exposure of 5 times at 35.5~39.5℃ and group D by exposure of 23day at 37~44℃ is less than 2.5%. Especially in the case of group D, we found that complete eradication of the insect is difficult despite exposure high temperature for a long time. Also most of the grinded Cninium officinale Makino has the same patten but group B by relatively treated low temperature has a significant difference in mortality. Insect mortality in cut Cninium officinale Makino by exposure at 35℃ and 39.5℃ is 7.5% and the insect mortality in grinded Cninium officinale Makino by exposure at 39. 5℃ is only 75%. The reason is estimated that heat conduction of grinded Cninium officinale Makino is slow and it was less shocked by heat because The final core temperature of medicinal herbs is relatively low about 0.5~2℃. This means that storage insect(Tribolium castaneum Herbst) can be suppressed at mid-high temperature if it is to be treated more than 50 days without problem of quality deterioration of medicinal herbs that can be caused by high temperature.

In this study, to apply hydrogen energy to ship engine and to generate effective hydrogen production, we investigated the effects of high temperature H₂SO₄ feed rate and cooling water rate to pump parts with fixed frequency needed to reciprocate motion and a simulation was conducted at each condition. In the fixed frequency and cooling water inlet flow rate of 0.5 Hz and 3.9 kg/s, we changed the high temperature H₂SO₄ flow rate to 47.46 kg/s (it is 105 % of 45.2 kg/s), 49.72 kg/s (110 %), and 51.98 kg/s (115 %). Also, at 0.5 Hz and 45.2 kg/s of frequency and high temperature H₂SO₄ flow, the thermal hydraulic analysis was performed at the condition of 95 % (3.705 kg/s), 90 % (3.51 kg/s), and 85 % (3.315 kg/s). In overall simulation cases, the physical properties of materials are more influential to the temperature increase in the pump part rather than the changes on the feed rate of high temperature H₂SO₄ and cooling water. A continuous operation of pump was also capable even if the excess feed of high temperature H₂SO₄ of about 15 % or the less feed of cooling water of about 15 % were performed, respectively. When the increasing feed of high temperature H₂SO₄ of up to 5 %, 10 %, and 15 % were compared with base flow (45.2 kg/s), the deviation of time period rose to a certain temperature and ranged from 0 to 4.5 s in the same position (same material). In case of cooling water, the deviation of time period rose to a certain temperature and ranged from 0 to 5.9 s according to the decreasing feed changes of cooling water at 5 %, 10 %, and 15 % compared to a base flow (3.9 kg/s). Finally, the additional researches related to the two different materials (Teflon and STS for Pitch and End-plate), which are concerned about the effects of temperature changes to the parts contacting different materials, are needed, and we have a plan to conduct a follow-up study.

목 적: 13.56 MHz Radio Frequency(RF) 고주파 송수신 장치를 만들고, 이를 이용하여 ITO안경렌즈 코팅 막의 두께와 전면커브에 대한 유도기전력 감소를 관찰하여 ITO 박막두께 측정을 연구하였다. 방 법: 전자빔 증착 장치를 이용하여 안경렌즈 하드 코팅 막 위에 다층막 코팅(SiO2/ZrO2/SiO2/ZrO2/SiO2/ITO/발수코팅막)을 하였는데, 이 때 ITO 코팅 시 이온빔 보조 장치를 사용하였다. 광투과율측정기로 ITO 코팅 안경렌즈의 투과율을 확인하였고, 13.56 MHz 수정발진소자를 사용하여 RF 고주파 송수신 장치를 만들었으며, 이 송수신 장치로부터 ITO 박막의 두께와 안경렌즈 커브에 의한 유도기전력의 감소량을 측정하였다. 결 과: 광투과율 측정 장치를 이용하여 ITO 안경렌즈 박막 두께에 따른 투과율을 측정한 결과, 가시광선 영역에서 ITO 박막이 두꺼워짐에 따라 처음에는 약간 증가하다가 점차 감소하는 경향을 나타내었다. 또한 RF 고주파 송수신 장치에서 안경렌즈를 RF 송수신 코일 위에 놓았을 때 유도기전력의 감소량은, 각각의 커브에서 ITO 두께가 커짐에 따라 유도기전력의 감소량이 증가함을 알 수 있었다. 또한 안경렌즈를 RF 송수신 코일 위에 놓았을 때 유도기전력의 감소량이 안경렌즈를 RF 송수신기 코일 안에 놓았을 때 유도기전력의 감소량보다 큰 것을 알 수 있었다. 결 론: 13.56 MHz RF 고주파 송수신 장치를 만들고, 이를 이용하여 ITO 안경렌즈 코팅 막의 두께와 전면커브에 대한 유도기전력 감소를 관찰한 결과, 안경렌즈를 RF 송수신코일 위에 놓았을 때 유도기전력의 감소량은 각각의 커브에서 ITO 두께는 커짐에 따라, 안경렌즈 전면 커브는 작아짐에 따라 증가함을 알 수 있었다.

The current concern about these materials (MoSi2 and NbSi2) focuses on their low fracture toughness below theductile-brittle transition temperature. To improve the mechanical properties of these materials, the fabrication of nanostructuredand composite materials has been found to be effective. Nanomaterials frequently possess high strength, high hardness, excellentductility and toughness, and more attention is being paid to their potential application. In this study, nanopowders of Mo, Nb,and Si were fabricated by high-energy ball milling. A dense nanostructured MoSi2-NbSi2 composite was simultaneouslysynthesized and sintered within two minutes by high-frequency induction heating method using mechanically activated powdersof Mo, Nb, and Si. The high-density MoSi2-NbSi2 composite was produced under simultaneous application of 80MPa pressureand an induced current. The sintering behavior, mechanical properties, and microstructure of the composite were investigated.The average hardness and fracture toughness values obtained were 1180kg/mm2 and 3MPa·m1/2, respectively. These fracturetoughness and hardness values of the nanostructured MoSi2-NbSi2 composite are higher than those of monolithic MoSi2 orNbSi2.

Nanocrystalline materials have received much attention as advanced engineering materials with improved physical and mechanical properties, including high strength, high hardness, excellent ductility and toughness. In this study, nanopowders of Al2O3, MgO and TiO2 were prepared as starting materials by high energy ball milling for the simultaneous synthesis and sintering of the nanostructured compound Mg4Al2Ti9O25 by high-frequency induction heating process. The highly dense nanostructured Mg4Al2Ti9O25 compound was produced within one minute by the simultaneous application of 80MPa pressure and induced current. The sintering behavior, grain size and mechanical properties of the Mg4Al2Ti9O25 compound were evaluated.

고주파 처리는 파밤나방(Spodoptera exigua)의 생리변화를 유발시켜 섭식행동, 발육 및 면역반응의 변화를 초래한다. 본 연구는 이러한 고주파의 영향을 파밤나방의 생화학적 변화를 통해 분석했다. 고주파(5,000 Hz, 95 dB) 처리는 중장 상피세포의 단백질 합성과 분비를 억제시켰다. 또한 이 고주파 처리는 중장의 인지질분해(phospholipase ) 소화효소의 활성을 현격하게 억제시켰다. 고주파 처리는 세 종류의 열충격단백질과 지질운송단백질(apolipophorin III)의 유전자 발현을 변동시켰고 이러한 변화는 중장 조직에서 뚜렷했다. 혈림프 혈장에 존재하는 지질 및 유리당의 함량이 고주파 처리에 의해 현격하게 증가했다. 이러한 결과는 고주파 처리가 파밤나방의 체내 생화학적 변화를 유발시켜 생리적 교란을 유도하는 스트레스로 작용한다는 것을 제시하고 있다.

This study deals with the high frequency induction hardening (HF at 850℃, 120kHz & 50kW condition) SM45C steel. (1) The HF specimen, which was tempered at 150℃, did not show any tempering effect. A brittle fracture occurred at rounded area of the tensile specimen. AE (acoustic emission) amplitude distribution showed between 45dB and 60dB. (2) A slip and fracture occurred at the hole area of the HF specimen which was tempered at 300℃. As they pass the yield point, the AE energy is increased intermittently and AE amplitude distribution exists between 70dB and 85dB. In addition, after imposing the maximum tensile load, AE signals showed high amplitude and energy distribution. The AE amplitude showed between 45dB and 70dB. (3) A brittle fracture occurred at HF specimen which was tempered at 450℃ as if it is torn in the direction of 45° on parallel area over the both sides of the tensile specimen, which lead to several peak appeared in AE energy. It was found that the AE amplitude was relatively low and the AE energy was high.

This study is deal with the high frequency induction hardening (HF at 850℃, 120kHz & 50kW condition) SM45C steel. (1) The HF specimen which was tempered at 150℃, did not appear any tempering effect. A brittle fracture occurred at rounded area of the tensile specimen. AE amplitude distribution showed between 45~60dB. (2) The HF specimen which was tempered at 300℃, slip and fracture occurred at the hole area of the tensile specimen. As it passes the yield point, the AE energy increased intermittently and AE amplitude distribution showed between 70~85dB. In addition, after the maximum tensile load, it showed high amplitude and energy distribution. The AE amplitude showed between 45~70dB. (3) The HF specimen which was tempered at 450℃, a brittle fracture occurred as if it is torn in the direction of 45℃ on parallel area over the both sides of the tensile specimen, which led to several peak to be appeared in AE energy. It was found that the AE amplitude was relatively low and the AE energy was high.

Nanopowders of and FeAl were fabricated by high energy ball milling. Dense 4.25 composite was simultaneously synthesized and consolidated by high frequency induction heated combustion method within 2 min from mechanically activated powders. Consolidation was accomplished under the combined effects of a induced current and mechanical pressure of 80 MPa.

Nanostructured was synthesized to have high density via rapid and cost effective process named as high-frequency induction heated combustion synthesis(HFIHCS) method. For the process, mechanically activated Re-Si powder was used, which had been prepared by mechanical ball milling of Re and Si powders with mixing ratio of 1:1.75. Both combustion synthesis and densification were accomplished simultaneously by applying electric current and mechanical pressure of 80 MPa during the process. The average grain size, hardness, and fracture toughness of the compound were 210 nm, 1085 and 4 , respectively. The experimental results show that HFIHCS is a promising process for synthesis of nanostructured which has a potential for both high temperature and thermo-electric applications

Dense nanostructured was synthesized by high-frequency induction-heated combustion synthesis (HFIHCS) method within 1 minute in one step from mechanically activated Nb and Si powders. Highly dense with relative density of up to 99% was simultaneously synthesized and consolidated under the combined effects of an induced current and mechanical pressure of 60 MPa. The average grain size and mechanical properties (hardness and fracture toughness) of the compound were investigated

High temperature dielectric constants of the various ceramic materials have been measured using cavity perturbation method. The measurements were applied to refractory, traditional and fine ceramic powder compacts from room temperature to . Calibration constant in the equation suggested by Hutcheon et al., was determined from the dielectric constants of reference specimen (teflon and alumina) at room temperature. From these results, informations on the refectory materials were obtained for the microwave kiln design and understanding of the microwave heating effects of ceramics have been improved.

본 연구의 목적은 높은 진동수 성분의 진동원을 가지는 건축물의 바닥판을 효율적으로 해석하는 방법을 제시하는 것이다. 이를 위하여 고차진동하중을 받는 건축물의 바닥판에 적절한 요소분할 방법과 이에 따른 과도한 자유도를 줄이기 위한 자유도 선택방법에 대하여 연구하였다. 그리고 일반적으로 건축물의 바닥판의 경우에는 두께에 비하여 바닥판의 길이가 길기 때문에 전단변형이 고려되지 않은 판요소를 바닥판의 모형화에 많이 사용하는데 이에 대해서도 그 적절성을 검증하였다. 그리고 여러 개의 층으로 이루어진 건축물 바닥판을 기존의 방법을 이용하여 등가의 바닥판으로 치환하였으며 이 방법의 가능성과 한계를 검토하였고 마지막으로는 예제 구조물을 중심으로 제안한 모형화 방법의 효율성을 확인하였다.