The Animal and Plant Quarantine Agency conducts a targeted sampling plan and analysis for veterinary drugs within the country every year. Target compounds included tetrachlorvinphos as an organophosphate, diminazene as an anti-infective medication, ketoprofen as a nonsteroidal anti-inflammatory drug, triclabendazole and clorsulon as flukicides in 2022. These compounds were not included in National Residues Program (NRP), despite their high sales ranking. A total of 94 bovine muscle samples and 20 equine muscle samples were collected from various locations across the country. The analysis of target compounds in muscle was performed using LC-MS/MS coupled with Food code 8.3.1 revised in 2022. A 2 g sample of muscle tissue was extracted using a water: acetonitrile (1:4, v/v) solution, then cleaned up with C18 and hexane saturated with acetonitrile. Compounds were separated with C18 column and mobile phases consisted of 0.1% formic acid in water (A) and 0.1% formic acid in acetonitrile (B). All analytes exhibited good linearity with correlation coefficients (R2) higher than 0.992. The limit of quantification (LOQ) of these compounds ranged from 0.21 to 2.79 μg/kg except for diminazene (3.85~6.86 μg/kg). The average recoveries of these analytes were 89.45~129.13% in muscle at spiked level of 10 or 20 μg/kg. Relative standard deviations (%) (intra-day and inter-day) were lower than 20% for all target compounds, except for diminazene and triclabendazole, whose intra-day RSD % was slightly higher than 20% in equine muscle. Testing confirmed that all 94 bovine and 20 equine muscle samples from 9 provinces were free from residues of veterinary drugs. Monitoring of compounds not included in the NRP should continue to ensure consumer health and food safety.

In order to investigate the optimum condition of the autofrettage process for the diesel engine fuel injection pipe, different values of autofrettage pressure, pressure rising time, pressure holding time, and repetition of autofrettage process were applied. Autofrettage was performed by applying the hydrostatic internal pressures of 604MPa, 535MPa, 500MPa on the fuel injection pipe, corresponding to theoretical 50%, 30%, and 20% overstrain levels, respectively. The autofrettage residual stresses in the injection pipe were experimentally determined by using X-ray diffractometer. As the overstrain level increased, the magnitude of compressive residual stress at the bore increased. It was found that the rising time to reach the autofrettage pressure, holding time at the autofrettage pressure, and repeated application of the autofrettage pressure on the pipe had no significant influence on the residual stress distributions.

현재, 국내에서는 가공식품인 식용유지에 대한 잔류농약 허용기준이 설정되어 있지 않아 잔류농약은 식용유 품질평 가의 사각지대라 할 수 있다. 본 연구에서는 식용유지에서 가열증류법을 이용하여 68종의 농약을 대상으로 추출 및 정 제법을 최적화하여 GC-MS/MS 분석법을 확립하였다. 가열 증류법은 가열온도 및 시간의 영향을 받았으며 이동상의 역 할을 하는 질소의 유량과 용출용매의 종류에는 큰 영향을 받지 않는 것으로 나타났다. 본 연구에서 잔류농약의 결정 계수(R2)는 0.99 이상으로 나타났고, 정량한계(LOQ)는 0.01- 0.02 mg/L이었으며, 대두유를 이용하여 0.01, 0.02, 0.1, 0.5 mg/L 수준으로 회수율 실험 결과 평균 회수율(n=5)은 66.1- 120.0%이었고 상대표준편차는 ±10%이하로 나타났다. 또한 실험실내 일간정밀도는 11%이하로 조사되어, 식품의약품안 전평가원의 ‘식품등 시험법 마련 표준절차에 관한 가이드라 인(2016)’에 적합한 수준임을 확인하였다. 따라서 본 연구에 서 개발한 시험법은 식용유지의 잔류농약 안전관리를 위한 시험법으로 활용이 가능할 것으로 기대된다.

This paper reports the results of an experimental examination using X-rays to test annealing materials for lapped bearing steel (STB2), to confirm the validity of the weighted averaging analysis method. The distribution behavior for the sin diagram and the presence or absence of differences in the peak method, half-value breadth method, and centroid method were investigated. When lapping the annealed bearing steel (STB2) material, a residual stress state with a non-directional steep gradient appeared in the surface layer, and it was found that the weighted averaging analysis method was effective. If there is a steep stress gradient, the sin diagram is curved and the diffraction intensity distribution curve becomes asymmetric, resulting in a difference between the peak method, half-value breadth method, and centroid method. This phenomenon was evident when the stress gradient was more than 2~3 kg/mm2/μm. In this case, if the position of the diffraction line is determined using the centroid method and the weighted averaging analysis method is applied, the stress value on the surface and the stress gradient under the surface can be obtained more accurately. When the stress gradient becomes a problem, since the curvature of the sin diagram appears clearly in the region of sin > 0.5, it is necessary to increase the inclination angle  as much as possible. In the case of a lapping layer, a more accurate value can be obtained by considering  in the weighted averaging analysis method. In an isotropic biaxial residual stress state, the presence or absence of  can be determined as the presence or absence of strain for sin≈0.4.

This study aims to establish a modified analytical method with sensitivity and reliability for streptomycin (STP) and dihydrostreptomycin (DHS) of residues level in pig tissues, plasma and urine by LC-MS/MS on the basis of previous studies. The mass parameters of quantitative and qualitative ions for STP and DHS were optimized using multiple reaction monitoring in positive mode. The separation of compounds was conducted using BEH Amide column according to material’s characteristics. The analytes in plasma were extracted with only organic solvents. In muscle and kidney, KH2PO4 buffer solution containing 2% CCl3COOH and EDTA-Na was used as extraction solvent. The WCX cartridege was selected as SPE cartridge in considering high recoveries for STP and DHS. The analytes in urine were extracted by organic solvents with acid and addition of EDTA. The limits of detection (LODs) in STP and DHS ranged 0.45~3.66 μg/kg and 0.22~0.78 μg/kg, respectively. The limits of quantification (LOQs) were 1.35~11.10 μg/kg in STP and 0.66~2.36 μg/kg in DHS. The recoveries (%) were 94.29~104.5% in STP and 92.32~108.45% in DHS except for plasma with lower values (61.45/68.5%, respectively). In the precision evaluation, the coefficient of variation (CV, %) of STP showed <10.50% on intra-day and <18.04% on inter-day. The CV (%) of DHS showed <8.42% on intra-day, whereas <17.98% on inter-day. The modified method is reliable for continuous residual monitoring in pig to ensure food safety for consumer’s health. In addition, this method could be used in study relation to residue depletion and pharmacokinetics of veterinary drug.

본 연구에서는 농산물 시료 중 GC-ECD/MS 분석법을 이용 하여 국내에서 사용금지된 잔류성 유기염소계 살충제 19종 (aldrin, α-BHC, β-BHC, γ-BHC, δ-BHC, cis-chlordane, trans-chlordane, p,p'-DDT, o,p'-DDT, p,p'-DDE, p,p'-DDD, dieldrin, endrin, δ-keto-endrin, heptachlor, heptachlor epoxide, α-endosulfan, β-endosulfan 및 endosulfan sulfate)에 대해 동시분석법을 확립하였다. 농산물 시료에 acetone을 가하여 추출된 대상농약 19종의 잔류분은 n-hexane 분배법과 florisil 흡착 크로마토그래피법으로 정제하여 분석대상 시료로 하였다. DB- 5 capillary column을 이용한 GC-ECD 분석 시 불순물의 간섭은 없었으며, 사과, 고추, 배추, 현미 및 콩을 포함한 5종의 대표 농산물 중 대상농약 19종 각각의 정량한계(LOQ)는 각 0.003~0.01 mg/kg 수준이었다. 5종의 대표 농산물에 대한 대상농약 전체의 회수율은 76.5~116.0%를 나타내었으며, 농산물 시료 및 처리수준에 관계없이 10% 미만의 분석오차를 나타내어 잔류분석기준 이내를 만족하였다. 본 연구에서 확립된 국내 사용금지 잔류성 유기염소계 살충제 19종의 동시분석법은 검출한계, 회수율 및 분석오차 면에서 국제적 분석기준을 만족할 뿐만 아니라, GC/MS SIM을 이용한 잔류분의 재확인 과정의 결과를 종합해 볼 때 분석과정의 편이성 및 신뢰성이 확보된 동시분석법으로 국내·외 수출입 및 유통 농산물의 잔류농약 검사에 사용 가능할 것이다.

본 연구에서는 농산물 시료 중 GC-NPD/MS 분석법을 이용하여 물리화학적 특성이 유사한 유기인계 살충제 chlorpyrifosmethyl, mecarbam, parathion-methyl, phenthoate, prothiofos, tebupirimfos, 유기인계 살균제 iprobenfos 및 유기인계 제초제 anilofos를 포함하는 8종의 유기인계 농약에 대해 동시 분석법을 확립하였다. 농산물 시료에 acetone을 가하여 추출된 대상 농약 8종의 잔류분은 n-hexane 분배법과 florisil 흡착 크로마토그래피법으로 정제하여 분석대상 시료로 하였다. DB-17 capillary column을 이용한 GC-NPD 분석 시 불순물의 간섭은 없었으며, 감귤, 고추, 배추, 현미 및 콩을 포함한 5종의 대표 농산물 중 대상농약 8종 각각의 정량한계(LOQ)는 tebupirimfos, chlorpyrifos-methyl 및 parathion-methyl은 0.004 mg/kg, 그 외 iprobenfos, mecarbam, prothiofos, phenthoate 및 anilofos는 0.008 mg/kg이었다. 5종의 대표 농산물에 대한 대상농약 전체의 회수율은 80.5~105.0%를 나타내었으며, 농산물 시료 및 처리수준에 관계없이 10% 미만의 분석오차를 나타내어 잔류분석기준 이내를 만족하였다. 본 연구에서 확립된 유기인계 농약 8종(anilofos, chlorpyrifos-methyl, iprobenfos, mecarbam, parathion-methyl, phenthoate, prothiofos 및 tebupirimfos)의 동시 분석법은 검출한계, 회수율 및 분 석오차 면에서 국제적 분석기준을 만족할 뿐만 아니라, GC/ MS SIM을 이용한 잔류분의 재확인 과정의 결과를 종합해 볼 때 분석과정의 편이성 및 신뢰성이 확보된 계열별 동시 분석법으로 국내·외 수출입 농산물 잔류농약 검사에 사용 가능할 것이다.

To improve life time of machine components, higher alloy grade materials are used by adding more metal alloy components and content. Also production processes are further complicated and subdivided such as the forging, preliminary heat treatment, quality heat treatment, rough machining and finished machining process. Those reasons become major cause of large stress in the materials, and the residual stress generated during the manufacturing process causes fatal defects, such as crack, surface tear, warping and deformation of the products. It is necessary to evaluate the residual stress on the entire processes, from forging process to final finished machining process. Also in order to avoid those problems caused by residual stresses, it is necessary to know in advance what process is important to be controlled and what parameters affect residual stress. By the hole drilling method, residual stress was measured in each manufacturing process step. In this study, the hardness of the surface, the cutting force test and the metal analysis were performed to clarify the influence of manufacturing process parameters.

In the seismic design of building structural members, due to the complexity of the placement of PC steels in prestressed concrete members, it is necessary to review and define the definition of member damage in comparison with reinforced concrete members.In this study, the results of past experiments compared with the calculation results by ‘section Analysis Method’, with the aim of reviewing the precision of calculation results when member damage evaluation is performed using the section analysis method. Furthermore, it is also compared with the calculation results by the ‘split Element Method’.In addition, parametric studies were carried out, and the influence of the difference between the amount of PC steels and reinforced bar on the residual strain was examined.

The residual stress analysis and fatigue test of a steel plate with a hole were performed in order to investigate the effects of the cold expansion on the fatigue life of the plate. The cold expansion method is a metal forming process by expanding a hole in order to induce compressive tangential residual stresses near the hole. In this research, a S45C steel plate of 3.2 mm thickness with a hole of 4.318 mm diameter was cold expanded by using a mandrel, resulting in a degree of expansion 1.47%. A significant amount of compressive tangential residual stress of 502 MPa at the hole surface was calculated using the finite element analysis and the compressive residual stress was more widely spreaded in the entry and exit planes than the mid plane in the plate thickness. The compressive tangential residual stresses showed a very beneficial influence on the fatigue life of the plate by increasing 1.2 to 2 times longer lives compared to the plate without cold expansion, depending on the applied load levels. Fatigue crack initiated and propagated at the hole surface of the mandrel entrance region, where relatively lower magnitude of compressive residual stress was found than the other region.

Carbon contamination from the binder resin is an inherent problem with the metal powder injection molding process. Residual carbon in the W-Cu compacts has a strong impact on the thermal and electric properties. In this study, uncertainty was quantified to evaluate determination of carbon in a W-15%Cu MIM body by the combustition method. For a valid generalization about this evaluation, uncertainty scheme applied even to the repeatability as well as the uncertainty sources of each analyse step and quality appraisal sources. As a result, the concentration of carbon in the W-Cu part were measured as 0.062% with expanded uncertainty of 0.003% at 95% level. This evaluation example may be useful to uncertainty evaluation for other MIM products.

최 등1)은 total lagrangian formulation에 근거한 증분 평형방정식을 적용하고, 강도행렬 산정시 회전각의 2차항을 포함시켜 기하학적 비선형 해석시 해의 수렴성을 향상시켰다. 또한 등매개 쉘 유한요소의 단점인 전단구속 현상과 제로 에너지 모드가 발생하는 문제를 극복하기 위하여 가정 변형률장을 적용하여 보강된 판 및 쉘 구조의 비선형 해석법을 개발하였다. 본 연구에서는 잔류응력을 고려한 쉘구조의 극한강도 해석을 수행하기 위하여, 대변형거동과 함께 소성붕괴거동을 추적할 수 있는 알고리즘을 제시한다. 잔류응력을 고려한 증분평형방정식에 return mapping algorithm을 이용한 탄소성 해석법을 결합시켜서 보강된 판 및 쉘구조의 극한거동을 파악한다. 수치해석 예제를 통하여 본 연구에서 제시된 유한요소 및 비선형 해석 알고리즘에 대한 효율성 및 적용성을 확인하였다.