This study investigates the thermal shock property of a polycrystalline diamond compact (PDC) produced by a high-pressure, high-temperature (HPHT) sintering process. Three kinds of PDCs are manufactured by the HPHT sintering process using different particle sizes of the initial diamond powders: 8-16 μm (D50 = 4.3 μm), 10-20 μm (D50 = 6.92 μm), and 12-22 μm (D50 = 8.94 μm). The microstructure observation results for the manufactured PDCs reveal that elemental Co and W are present along the interface of the diamond particles. The fractions of Co and WC in the PDC increase as the initial particle size decreases. The manufactured PDCs are subjected to thermal shock tests at two temperatures of 780oC and 830oC. The results reveal that the PDC with a smaller particle size of diamond easily produces microscale thermal cracks. This is mainly because of the abundant presence of Co and WC phases along the diamond interface and the easy formation of Co-based (CoO, Co3O4) and W-based (WO2) oxides in the PDC using smaller diamond particles. The microstructural factors for controlling the thermal shock property of PDC material are also discussed.

The present study deals with the effects of micro-alloying elements such as Ni, V, and Ti on the recrystallization behavior of carbon steels at different strain rates. Eight steel specimens were fabricated by varying the chemical composition and reheating temperature; then, a high-temperature compressive deformation test was conducted in order to investigate the relationship of the microstructure and the recrystallization behavior. The specimens containing micro-alloying elements had smaller prior austenite grain sizes than those of the other specimens, presumably due to the pinning effect of the formation of carbonitrides and AlN precipitates at the austenite grain boundaries. The high-temperature compressive deformation test results indicate that dynamic recrystallization behavior was suppressed in the specimens with micro-alloying elements, particularly at increased strain rate, because of the pinning effect of precipitates, grain boundary dragging and lattice misfit effects of solute atoms, although the strength increased with increasing strain rate.

PURPOSES: This study was initiated to analyze the characteristics of bus traffic accidents, by bus types, using the decision tree in order to establish customized safety alternatives by bus types, including the intra-city bus, rural area bus, and inter-city bus. METHODS: In this study, the major elements involved in bus traffic accidents were identified using decision trees and CHAID algorithm. The decision tree was used to identify the characteristics of major elements influencing bus traffic accidents. In addition, the CHAID algorithm was applied to branch the decision trees. RESULTS : The number of casualties and severe injuries are high in bus accidents involving pedestrians, bicycles, motorcycles, etc. In the case of light injury caused by bus accidents, different results are found. In the case of intra-city bus accidents, the probability of light injury is of 77.2% when boarding a non-owned car and breaching of duty to drive safely are involved. In the case of rural area bus accidents, the elements showing the highest probability of light injury are boarding an owned car, vehicle-to-vehicle accidents, and breaching of duty to drive safely. In the case of intra-city bus accidents, boarding owned car, streets, and vehicle-to-vehicle accidents work as the critical elements. CONCLUSIONS: In this study, the bus accident data were categorized by bus types, and then the influential elements were identified using decision trees. As a result, the characteristics of bus accidents were found to be different depending on bus types. The findings in this study are expected to be utilized in establishing effective alternatives to reduce bus accidents.

Activated carbons (ACs) have been used as EDLC (electric double-layer capacitor) electrode materials due to their high specific area, stability, and ecological advantages. In order to prepare ACs with high density and crystallinity, coal tar pitch (CTP) was activated by K2CO3 and the textural and electrochemical properties of the obtained ACs were investigated. Although the CTP ACs formed by K2CO3 activation had much smaller specific surface area and pore volume than did the CTP ACs formed by KOH activation, their volumetric specific capacitance (F/cc) levels as electrode materials for EDLC were comparable due to their higher density and micro-crystallinity. Structural characterization and EDLC-electrode performance were studied with different activation conditions of CTP/K2CO3 ratio, activation temperature, and activation period.

노후 원전 해체의 경우 부지 특성 및 최종 상태 조사 보고서에 해당 부지내 잔존가능성이 있는 방사성 핵종 정보에 대한 내용 을 포함하여야 한다. 미국 NRC의 경우 이에 해당하는 해체기술관련문서(DTBD)를 부지 특성 조사시에 부지이력조사(HSA) 와 같이 사업자 측이 제출하도록 규제하고 있다. 또한 해체기술관련문서는 방사선학적 부지 조사와 해체완료계획서에 포함 되어야 하는 내용으로써 부지 규제 해제와 재이용에 관해서 중요한 자료를 제공한다. 이 논문은 부지 별 잠재적 핵종에 대해 미국 원전의 해체 사례중 부지 특성 및 최종 상태조사 과정에서 결정하는 방법론을 분석하고 2017년 고리 1호기의 영구 운 전정지 후 이루어질 해체 과정에 필수적인 규제 지침과 기술적 근거 수립에 도움이 되고자 한다.

사회적기업에 대한 전 세계적 관심은 다양한 영역에서 확산되고 있으며, 우리나라 역시 사회적기업에 대한 정책적, 실무적 및 학문적 관심이 증가하고 있다. 그럼에도, 기존연구는 조직관리 혹은 인적자원관리 이슈들을 다루는데 소홀해왔고, 종사자를 대상으로 한 실증연구와 논의 역시 초기 단계이다. 사회적기업 은 영리조직보다 종업원의 동기를 유발시키는 것이 더 중요할 수 있고, 자기결정이론(Self determination theory)은 사회적기업 종업원들의 직무동기와 조직 유효성 관계를 설명하는데 유용한 틀을 제공할 수 있 다. 이에 본 연구는 사회적기업 종업원의 직무동기가 조직몰입 및 조직시민행동에 미치는 영향과 이 관계 에서 민주적 의사결정의 조절역할을 분석하고자 한다. 실증분석결과는 다음과 같다. 첫째, 직무동기(외재 적, 투사적 및 내재적 동기)는 조직몰입과 조직시민행동에 모두 정(+)의 영향을 미치는 것으로 나타났다. 내재적 동기는 조직몰입과 조직시민행동에 모두 유의적인 정(+)의 영향을 미쳤다. 반면, 투사적 동기는 조직시민행동에 유의미한 영향을 미치지만 조직몰입에는 한계적 수준으로 영향을 미쳤고, 외재적 동기는 조직몰입에 유의미한 영향을 미치지만 조직시민행동에는 한계적 수준으로 영향을 미치는 것으로 나타났 다. 둘째, 민주적 의사결정의 조절역할과 관련하여, 민주적 의사결정은 내재적 동기와 조직 유효성(조직몰 입, 조직시민행동) 간 관계를 조절하였으나 외재적 동기와 투사적 동기와 조직 유효성 간 조절효과가 나 타나지 않았다. 사회적기업가들은 종업원의 내재적 동기를 강화시키기 위한 다양한 비금전 인센티브 등 이 중요함을 시사하였다. 결론에는 연구결과, 시사점 및 연구의 한계점 등이 논의 되었다.

본 연구는 여자 아이돌 그룹에 대한 선호도 및 팬덤 활동 참여 의도 결정 요인을 살펴보기 위한 것이다. 주요 연구 결과들은 다음과 같다. 첫째, 여자 아이돌 그룹 유형별 선호도 결정 요인 을 일반 기획사 및 메이저 기획사 소속 아이돌에 대한 선호도로 구분해 살펴보았다. 일반 기획사 소속 여자 아이돌 그룹 선호도 결정 요인은 외부 선호도와 여성적 매력이 정적으로 영향을 미치 는 것으로 나타났다. 성별 요인은 남자 응답자들의 선호도가 높은 것으로 나타났다. 메이저 기획 사 소속 여자 아이돌 그룹 선호도의 경우, 음악성 및 여성적 매력이 통계적으로 의미 있는 설명 요인으로 나타났다. 둘째, 여자 아이돌 그룹 팬덤 활동 참여 의도를 결정하는 요인을 살펴본 결 과, 음악성을 포함해 외부 선호도와 여성적 매력 요인들이 포함되는 것으로 나타났다. 또한, 여 자보다는 남자 응답자들의 팬덤 활동 참여 의도가 증가하는 것으로 나타났다.

본 연구는 코칭과 자기결정성이론의 관계를 고찰하고 적용점을 탐색하기 위한 목적으로 실 시하였다. 이를 위해 자기결정성 이론을 이루고 있는 인지평가이론, 유기체통합이론, 인과성지 향이론, 기본심리욕구이론, 목표내용이론 및 관계동기이론의 핵심적인 내용을 기술하고, 코칭 과의 관련성 및 적용점을 제시하였다. 첫째, 자기결정성 이론의 인간관은 인본주의 철학을 기 반으로 한 코칭 패러다임과 맥을 같이하며, 자기결정성 이론이 코칭철학에 심리학적 근거를 제공할 수 있음을 논의하였다. 둘째, 코칭 과정에서 자기결정성 이론을 고객과의 관계 맺기 및 목표 설정에 활용할 수 있음을 보여주었다. 셋째, 자기결정성이론으로 코칭의 중요 기술인 경청, 질문, 피드백과 고객의 기본심리욕구와의 관계를 설명하였다. 코치의 개입은 고객의 자 율성, 유능성, 관계성을 충족시키는 차원에서 활용할 때 효과적이다. 마지막으로 코칭 환경과 코치 자신에 대한 이론의 적용과 관련하여, 단기성과에 대한 압박의 해결과 코치 자신의 심리 적 욕구를 보살피는 노력의 필요성에 대해 논의했다. 자기결정성이론은 코칭의 학문적인 토대 를 강화하고, 실제 코칭의 효과성을 높이기 위해 주목해야 할 이론이다.

It is important to select proper ground motions for obtaining accurate results from response history analyses. The purpose of this study is to propose an accurate and efficient method that does not require excessive computation for selecting and scaling ground motions to match target response spectrum mean and variance. The proposed method is conceptually simple and straightforward, and it does not use a simulation algorithm that requires a sophisticated subroutine program. In this method, the desired number of ground motions are sequentially scaled and selected from a ground motion library. The proposed method gives the best selection results using Sum of Square Error and has the smallest value(=0.14). Also, The accuracy and consistency of the proposed method are verified by comparing the selection results of the proposed method with those of existing methods.

Recently, pollution problem in coastal water has become more serious and pollution including red tide serves as a main reason for reduction of fishes resources. Particularly, nutrients such as nitrogen and phosphorus are the most serious pollutants. Normally, biological wastewater treatment process is used in removing such nutrients. However, it is difficult to adopt the biological wastewater treatment process to a small-scale fish processing factory in case of using seawater as wash water. Thus, removing nutrients through struvite crystallization is investigated in this study for treating shrimp processing wastewater. Experiments were conducted by varying molar ratio of Mg2+:NH4-N:PO4-P from 1:1:1 to 2:1:1. It can be concluded that optimum molar ratio is 1:1:1. Struvite crystallization process is compared with chemical coagulation process using PAC and struvite crystallization process is proven as the more effective process in removing nutrients from wastewater. In view of results obtained from these experiments, struvite crystallization process is a promising method in removing nitrogen and phosphorus from wastewater; however, not so good in removing organics. Thus, struvite crystallization process is suitable as the pre-treatment process in treating shrimp processing wastewater and additional biological process is needed to remove organics.

With the increase in installed solar energy capacity, comparison and analysis of the physical property values of solar cells are becoming increasingly important for production. Therefore, research on determining the physical characteristic values of solar cells is being actively pursued. In this study, a diode equation, which is commonly used to describe the I-V behavior and determine the electrical characteristic values of solar cells, was applied. Using this method, it is possible to determine the diode ideality factor (n) and series resistance (Rs) based on light I-V measurements. Thus, using a commercial screen-printed solar cell and an interdigitated back-contact solar cell, we determined the ideality factor (n) and series resistance (Rs) with a modified diode equation method for the light I-V curves. We also used the sun-shade method to determine the ideality factor (n) and series resistance (Rs) of the samples. The values determined using the two methods were similar. However, given the error in the sun-shade method, the diode equation is considered more useful than the sun-shade method for analyzing the electrical characteristics because it determines the ideality factor (n) and series resistance (Rs) based on the light I-V curves.

Ni(OH)2 hollow spheres have been prepared by solvent displacement crystallization using a micro-injection device, and the effect of process parameters such as concentration and the relative ratio of the injection speed of the precursor solution, which is an aqueous solution of NiSO4·6H2O, to isopropyl alcohol of displacement solvent have been investigated. The crystal phases after NaOH treatment are in the β-phase for all process parameters. A higher concentration of NiSO4·6H2O aqueous solution is injected by a micro-injection device and bigger Ni(OH)2 hollow spheres with a narrower particle size distribution are formed. The crystallinity and hardness of the as-obtained powder are so poor that hydrothermal treatment of the as-obtained Ni(OH)2 at 120oC for 24 h in distilled water is performed in order to greatly improve the crystallinity. It is thought that a relative ratio of the injection speed of NiSO4·6H2O to that of isopropyl alcohol of at least more than 1 is preferable to synthesize Ni(OH)2 hollow spheres. It is confirmed that this solution- based process is very effective in synthesizing ceramic hollow spheres by simple adjustment of the process parameters such as the concentration and the injection speed.

Muffin was developed using blueberry powder and the shelf life of the muffin packaged in modified atmosphere was determined. Blueberry was freeze-dried and milled to prepare powder. As the concentration of blueberry powder increased from 0 to 15% (w/w), hardness and gumminess also increased (p<0.05). The Hunter L and b values of the crust and crumb of muffin decreased as the concentration increased, while their Hunter a values increased. Blueberry powder concentrations of 10 and 15% resulted in high preference in taste, texture, and overall acceptability. Blueberry muffin containing powder at 10% was packaged in modified atmosphere (MA). The optimum gas for modified atmosphere packaging (MAP) of the muffin was the mixture of carbon dioxide (CO2) and nitrogen (N2) (7:3), which improved microbial stability without altering muffin hardness. The shelf life of modified atmosphere packaged blueberry muffin was determined using the accelerated life test. The shelf life values for MA packaged blueberry muffin stored at 25 and 35°C were predicted as 21 and 5 d, respectively. Further, the Q10 values for 25- 35°C and 35-45°C were determined as 4.2 and 2.9, respectively. The MAP can preserve blueberry muffin for 3 weeks at 25°C, without the external addition of preservatives.

URPOSES: The objective of this study was to develop an impact resonance (IR) test procedure for thin disk-shaped specimens in order to determine the ⎢E*⎢ and phase angle values of various asphalt mixtures. METHODS: An IR test procedure was developed for evaluating thin disk-shaped specimens, in order to determine the dynamic modulus (⎢E*⎢) of various asphalt mixtures. The IR test method that was developed to determine the elastic modulus values of Portland cement concrete was evaluated, which method uses axisymmetric flexural vibration proposed by Leming et al. (1996). The IR tests were performed on three different mixtures of New York with varying nominal maximum aggregate sizes (NY9.5, NY19, and NY25) at six different temperatures (10 - 60℃). The ⎢E*⎢ values obtained from the IR tests were compared with those determined by the commonly used AASHTO T342-11 test. RESULTS AND CONCLUSIONS : The IR test method was employed to determine the ⎢E*⎢ values of thin-disk-shaped specimens of various asphalt mixtures. It was found that the IR test method when used with thin disk-like specimens is a simple, practical, and cheap tool for determining the ⎢E*⎢ values of field cores. Further, it was found the ⎢E*⎢ values obtained from the IR tests using thin disk-like specimens were almost similar to those obtained using the AASHTO T342-11 test.

본 연구는 두 나라로 구성된 개방 경제를 가정한 DSGE 모형을 통해 환율과 거시경제변수간의 단절현상(exchange rate disconnect)에 대한 분석과 이론적 근거를 제시하고자 한다. 기존의 DSGE 모형에 금융중개기관(financial intermediation sector)을 추가하여 환율결정과정에서 의 은행의 역할을 강조하였다. 2007년 국제금융위기이후로 최근의 자산가격연구(asset pricing theory)의 중요한 흐름은 자산가격형성에 있어서 은행이 가지는 자금조달제약(financial constraint) 의 영향을 강조하는 것이다. 본 연구에서도 은행은 1. 자국의 가계로부터의 예금조달만 가능하며 (segmented global deposit market), 2. 예금조달은 순자산 규모에 제약을 받는다(balancesheet constraint)는 두 가지 자금조달제약을 가정하였다. 이 두 가지 제약으로 인해 국가 간 소 비의 차이가 환율과 연결되지 않는다는 것을 이론적으로 분석함으로써, 환율과 거시경제변수간의 단절현상 중 하나인 배커스-스미스 퍼즐(Backus-Smith puzzle)에 대한 하나의 근거를 제공하였 다. 모형을 미국과 캐나다의 주요 거시 경제 변수 moment 들에 맞춘 실증 분석 결과, 두 나라의 소비 차이와 환율의 상관계수는 -0.25로 나타나 일반적으로 두 변수간 음(-)의 상관계수를 보이는 배커스-스미스 퍼즐과 부합하였다.

This paper analyzed what factors affect increased import from ASEAN agricultural products. This study uses multi-countries gravity model approach with a dataset of agricultural import for the period of 2004 - 2014 and several explanatory variables, and then estimate it using the random-effect panel Tobit. The results revealed that agriculture trade in Korea is influenced by the trade partner’s per capita GDP, population, distance from Korea, FTA preferential taxrate, trade percentage of GDP, agriculture percentage of GDP, the number of immigrants from ASEAN countries, and normal track dummy variables etc. It is found that FTA taxrate affect trade between both partners that can occur loss in agricultural industry. Therefore, applying deliberate standards strategies for normal track selection for future FTA negotiation.

풍하중에 취약하며, 모니터링에 다양한 모드가 고려되어야하는 초고층 빌딩에서 최적 센서의 위치 및 최적 개수를 결정하는 문제는 매우 중요하다. 본 논문에서는 고층빌딩의 모니터링을 위한 센서의 최적 개수 및 최적 위치의 결정 방법에 대해 제안한다. Kammer에 의해 제안된 유효영향법(Effective Influence Method)을 이용하여 특정 수의 센서가 설치될 최적의 위치를 결정하며, 추정 모드형상의 정확도에 관한 모니터링 목표 수준을 달성할 수 있는 최소의 센서수를 결정한다. 제안된 알고리즘의 사례연구로 25층의 건 물모형인 켄틸레버 구조물을 선정하여 수치해석을 수행하였다. 해석 결과 센서의 최적 위치 및 최적 개수, 계측 가능한 모드는 합리적으로 결정되는 것을 확인하였다.