대표적인 상업화된 박테리오신인 나이신은 Listeria monocytogenes 및 Staphylococcus aureus와 같은 병원성 세균에 대해 강력한 항균 활성을 보인다. 본 연구에서는 시판되는 나이신 제품을 박테리오파지 SAP84와 함께 병용 처리했을 때 S. aureus 억제에 대한 상승효과에 대하여 평가했다. S. aureus KCTC 3881 균주에 대해 나이신은 농도의존적으로 생균수를 감소시켰으며 18 IU/mL의 나이신은 대조구와 비교하여 6시간째에 4.03 Log CFU/mL의 균수가 감소된 반면, 동일 용량의 나이신이 박테리오파지 SAP84 (0.1 MOI)와 병용처리 되었을 때 5.54 Log CFU/mL의 생균수 감소가 관찰되었다. 또한 나이신과 SAP84 의 조합은 양상추에서 S. aureus 균주를 효과적으로 제어하는데 성공적으로 적용되었다.

일부 대장균 균주는 독성을 가지고 있으며 이들을 제어 하기 위해 박테리오파지와 같은 대체 항균물질에 대한 연구가 활발히 진행되고 있다. 본 연구에서는 E. coli DH5α 균주를 모델로 이 균주의 생육을 억제하는 박테리오파지 ECP27과 병용처리했을 때 상승효과를 나타낼 수 있는 항균물질을 탐색하였다. 후보물질로는 CaCl2, 젖산, 구연산 이 사용되었다. CaCl2의 경우 6시간째 농도 의존적으로 생육억제 상승효과가 나타났으나 12시간째 E. coli DH5α의 생균수가 회복되는 추세를 보였다. 그러나 30mM 농도에 서 젖산과 구연산은 박테리오파지 ECP27과 병용처리 했을 때 E. coli DH5α의 생육저해에 대하여 6시간째 상승 효과를 보였으며 12시간째 생균수가 검출되지 않았다. 또한 젖산과 구연산을 단독으로 처리했을 때 12시간째 E. coli DH5α의 생균수가 확인되지 않아 독자적으로도 항균력이 우수하였다. 따라서 박테리오파지와 유기산을 병용 처리하는 것은 대장균의 생육을 효과적으로 억제하는 좋은 전략이 될 수 있을 것이다.

The effect of physical and chemical treatments to reduce staphylococcal phages was investigated. To determine impact of physical treatment on viability of phages, two staphylococcal phages (SAP84 and SAP89) were treated with multiple heat (55oC and 60oC) and pH (pH4, 7, 10) conditions. Viability of SAP 84 was dramatically reduced at 60C and SAP 89 was completely inactivated at 60C within 25 min. Overall, the two phages were stable under all the pH conditions tested except for the SAP 89 at pH 10. Treatments, a 10% FAS (Ferrous Ammonium Sulfate) solution and various density of ethanol and sodium hypochlorite were used to reduce the two phages. SAP 84 was unstable in 50% and 70% ethanol. However, SAP 84 and SAP 89 showed high tolerance after exposure to 100 ppm of sodium hypochlorite which is known as an effective sterilizer. As soon as the two phages were treated with 10% FAS, which is used as a virucidal agent, they were inactivated and did not form any plaque. The result of this study provides additional evidence that staphylococcal phages can be controlled by various physicochemical treatments.

This study investigated the effects of the mixing ratio of tofu paste and normal corn starch on the characteristics of gluten-free (GF) muffins. Soft wheat flour for wheat flour-based muffins (control) was replaced with the mixture of tofu paste and normal corn starch (NCS). The mixing ratios of tofu paste and NCS were 1:6.4 (S100), 1:5.1 (S80), 1:3.8 (S60), 1:2.6 (S40), 1:1.3 (S20), and 1:0 (S00), based on their total solid contents. GF muffins of S40- S100 developed the porous, sponge-like structure without crumb collapse. The weight and baking loss did not significantly differ in the control and GF muffins. By decreasing NCS in GF muffin batters, the moisture content, firmness, and crumb redness/yellowness of GF muffins increased, while their volume, specific volume, and crumb lightness decreased. Nevertheless, these characteristics (except for firmness) of S100 were much closer to those of the control. In the preference test, however, S60 (possessing lower attributes than S100 and S80) was most favored among GF muffins, and was very similar in all evaluations (except for appearance) to the control. Overall, the mixture of tofu paste and NCS would be a potential material to replace soft wheat flour in muffins.

This study examined the effectiveness of integrated language instruction using dictogloss on vocabulary knowledge and retention. Forty EFL students from two classes of an elementary school participated in the study. The integrated language class and segregated language class were examined by looking into the effect of each instructional type on the vocabulary knowledge development and retention. A total of 10 target words were selected from a storybook related to their textbook. Four types of vocabulary knowledge were measured: passive recognition, passive recall, active recognition, and active recall. The pretest and posttest were performed to measure the vocabulary growth. The retention rate of each instruction was examined by conducting a delayed posttest on the same words after two weeks. The results of this study indicate that integrated language instruction using dictogloss works better in vocabulary retention. They also suggest that further classroom research is required to prove that dictogloss is an effective way for vocabulary learning.

There has been an accelerating increase in water reuse due to growing world population, rapid urbanization, and increasing scarcity of water resources. However, it is well recognized that water reuse practice is associated with many human health and ecological risks due to numerous chemicals and pathogenic microorganisms. Especially, the potential transmission of infectious disease by hundreds of pathogenic viruses in wastewater is one of the most serious human health risks associated with water reuse. In this study, we determined the response of different bacteriophages representing various bacteriophage groups to chlorination in real wastewater in order to identify a more reliable bacteriophage indicator system for chlorination in wastewater. Different bacteriophages were spiked into secondary effluents from wastewater plants from three different geographic areas, and then subjected to various doses of free chlorine and contact time at 5˚C in a bench-scale batch disinfection system. The inactivation of φX174 was relatively rapid and reached ∼4 log10 with a CT value of 5 mg/L*min. On the other hand, the inactivation of bacteriophage PRD1 and MS2 were much slower than the one for φX174 and only ~1 log10 inactivation was achieved by a CT value of 10 mg/L*min. Overall, the results of this study suggest that bacteriophage both MS2 and PRD1 could be a reliable indicator for human pathogenic viruses for chlorination in wastewater treatment processes and water reuse practice.

Cronobactersakazakii is a newly emerging high hazard pathogen, which causes encephalomeningitis and necrotic colitis. Recently, successful biocontrol of harmful microorganisms in several foods through the use of bacteriophages has been reported. In this study, bacteriophages were isolated from kimchi and sewages. Morphological analysis by TEM indicated that phages belonged to the Myoviridae family. In case of heat stability, KCES2 and ESP 2949-2 phages were susceptible to temperatures above 70oC. KCES2 and ESP 2949-2 phages inhibited the growth of C. sakazakii in culture broth. When KCES2 and ESP 2949-2 phages were applied to biofilm-formed C. sakazakii, C. sakazakii was efficiently reduced. Therefore, newly isolated KCES2 and ESP 2949-2 phage for C. sakazakii might effectively reduce C. sakazakii in various foods.

The aim of study was to investigate the virulence profile of Escherichia coli O157:H7 bacteriophages isolated from sewage and livestock stools. Among 23 E. coli O157:H7 bacteriophages, 14 strains were isolated from sewage and 9 were from animal stools collected from 10 livestock farms in Korea. For each bacteriophage DNA sample, the presence of stx1, stx2, eae, aafII, ial, elt, estI, estII, astA, afa, and cnf was examined by polymerase chain reaction. The detection rate of eae, stx2, estI, astA, and ial was 100%, 69.6%, 13.0%, 13.0%, 8.7%, respectively. While all E. coli O157:H7 bacteriophages isolated from stools carried eae+stx2, stx2+eae, eae+astA, eae, stx2+eae+estI, eae+estI, stx2+eae+ial, and eae+ial were observed in bacteriophages isolated from sewage. As several plasmid-carrying virulence factors (estI, astA, and ial) were found in E. coli O157:H7 bacteriophages obtained from sewage and stools, the microbial safety of bacteriophages should be investigated in further study.

본 연구에서는 7차 교육과정에서 크게 대두되고 있는 새로운 형태의 교수?학습방법의 한 형태인 e-Learning이 학습자의 파지에 어떠한 영향을 주는지 알아보고자 e-Learning을 이용하여 중학생들이 ‘지각의 물질’ 단원에서 장?단기 파지에 미치는 영향에 대해 알아보았다. 이를 위하여 경상남도 양산시의 중학교 1학년 2개 학급 72명을 대상으로 e-Learning을 활용한 수업 전-후에서 과학 학업 성취도와 e-Learning에 대한 인식을 조사해 본 결과는 다음과 같다. 첫째, e-learning 활용수업은 학습자의 단기파지에 효과를 나타내지 못하였다. 둘째, 장기파지에 미치는 효과는 유의수준 .05에서 유의미한 차이가 있는 것으로 나타났다. 셋째, e-Learning을 활용한 수업이 장기파지에 긍정적인 반응을 하는 것으로 나타났다.

본 연구의 목적은 '날씨와 기후' 단원에 대한 수업 후, 수업방법(설명식 수업과 발견식 수업)과 학습자의 인지양식에 따른 학업파지 효과를 조사하는 것이다. 연구대상은 광주에 있는 남자고등학교의 1학년 185명과 남여공학고등학교의 1학년 189명을 대상으로 하였다. 연구대상 학생들 중 남자고등학교의 92명과 남여공학고등학교의 95명을 설명식수업집단으로, 그리고 남자고등학교의 93명과 남여공학고등학교의 94명을 발견식 수업집단으로 선정하였다. 모든 학생들은 그들의 인지양식에 따라 장 독립적 학습자, 중간적 학습자, 장 의존적 학습자로 분류되었다. 연구 결과는 다음과 같이 요약할 수 있다. 첫째, 지구과학 학습내용의 수업 3주일 후 학업파지검사에서 발견식 수업방법이 설명식 수업방법에 비해 이해와 적용영역에서 더 효과적인 것으로 나타났다. 그러나 지식영역에 있어서는 유의미한 차이가 없었다. 둘째, 학업파지검사에서 장 독립적 인지양식의 학습자들이 장 의존적 인지양식의 학습자들에 비해 이해와 적용영역에서 더 효과적인 것으로 나타났다. 셋째, 학업파지검사에서 수업방법과 학습자의 인지양식 간의 상호연관성에 대한 유의미한 차이는 없었다.

In this paper, we present a learning platform for robotic grasping in real world, in which actor-critic deep reinforcement learning is employed to directly learn the grasping skill from raw image pixels and rarely observed rewards. This is a challenging task because existing algorithms based on deep reinforcement learning require an extensive number of training data or massive computational cost so that they cannot be affordable in real world settings. To address this problems, the proposed learning platform basically consists of two training phases; a learning phase in simulator and subsequent learning in real world. Here, main processing blocks in the platform are extraction of latent vector based on state representation learning and disentanglement of a raw image, generation of adapted synthetic image using generative adversarial networks, and object detection and arm segmentation for the disentanglement. We demonstrate the effectiveness of this approach in a real environment.

In robotic harvesting, a gripper to manipulate the fruits needs to be attached to the robot system. We proposed a flexible robot gripper that can actively respond to the shape of an object such as fruits in the previous work. However, we found that there is a possibility of not being reliably gripped when the object slides during contact with a finger. In this paper, the improved gripper design is proposed to fundamentally solve the problems of the previous gripper. The position of the finger and the maximum closed position are changed, and the design improvement is performed to increase the grip stability by changing the installation angle of the link portion of the finger. Based on the improved design, a modified gripper is fabricated by 3-D printing, and then gripping experiments are performed on spherical object and fruit model object. It is shown that the gripper can stably grip the objects without excessive bending of the finger link of the gripper. The contact pressure between the finger and the surface of the object is measured, and it is verified that it is a sufficiently small pressure that does not cause damage to the fruit. Therefore, the proposed gripper is expected to be successfully applied in harvesting.

This paper presents a control and operation system for a remotely operated vehicle (ROV). The ROV used in the study was equipped with a manipulator and is being developed for underwater exploration and autonomous underwater working. Precision position and attitude control ability is essential for underwater operation using a manipulator. For propulsion, the ROV is equipped with eight thrusters, the number of those are more than six degrees-of-freedom. Four of them are in charge of surge, sway, and yaw motion, and the other four are responsible for heave, roll, and pitch motion. Therefore, it is more efficient to integrate the management of the thrusters rather than control them individually. In this paper, a thrust allocation method for thruster management is presented, and the design of a feedback controller using sensor data is described. The software for the ROV operation consists of a robot operating system that can efficiently process data between multiple hardware platforms. Through experimental analysis, the validity of the control system performance was verified.

The optimal grasping point of the object varies depending on the shape of the object, such as the weight, the material, the grasping contact with the robot hand, and the grasping force. In order to derive the optimal grasping points for each object by a three fingered robot hand, optimal point and posture have been derived based on the geometry of the object and the hand using the artificial neural network. The optimal grasping cost function has been derived by constructing the cost function based on the probability density function of the normal distribution. Considering the characteristics of the object and the robot hand, the optimum height and width have been set to grasp the object by the robot hand. The resultant force between the contact area of the robot finger and the object has been estimated from the grasping force of the robot finger and the gravitational force of the object. In addition to these, the geometrical and gravitational center points of the object have been considered in obtaining the optimum grasping position of the robot finger and the object using the artificial neural network. To show the effectiveness of the proposed algorithm, the friction cone for the stable grasping operation has been modeled through the grasping experiments.

Continuous outbreaks of Shigella spp. have raised concerns about the lack of rapid and on-site applicable biosensor method for Shigella detection. Since a bacteriophage has recently been employed as an emerging bio-recognition element in biosensor method, Shigella sonnei-specific bacteriophage was isolated and purified from a slaughterhouse with the final concentration of 2.0×1012 PFU/mL in this study. Analysis of purified S. sonnei-specific bacteriophage using transmission electron microscopy indicated that it possessed an icosahedral head with a relatively long non-contractile tail. It was therefore classified as a member of the Siphoviridae family. Head width, head length, and tail length were 69.9±11.2 nm, 77.5±8.8 nm, and 264.4±33.9 nm, respectively. The genomic DNA size of the S. sonnei-specific bacteriophage was determined to be approximately 25 kb by using 0.4% agarose gel electrophoresis. In specificity test with 43 food-associated microorganisms, the S. sonnei-specific bacteriophage exhibited a clear plaque against S. sonnei only. In addition, the S. sonnei-specific bacteriophage was stable within a wide range of pH values (pH 3-11) and temperatures (4-37 ). Thus, the present study demonstrated the excellent specificity and stability of the S. sonnei-specific bacteriophage as a novel bio-recognition element for S. sonnei detection in foods.

이전에 학습한 자료에 대하여 시험을 쳐 보는 것은 강력한 학습 이벤트로 작용할 수 있다. 이를 시험 효과라고 하는데, 본 연구에서는 시험 효과 검정을 위한 중세국어-현대국어 단어쌍을 개발하 여 사용하였다. 본 연구에서는 이를 활용하여 초기 테스트, 단서 회상 테스트, 단기 파지 간격에 따른 집단 간의 차이를 살펴보았다. 그 결과, 초기 테스트 집단이 매우 유의미한 결과를 나타내었 다. 이것은 학습 후 빠른 시간 안에 초기 테스트가 필요함을 강력히 지지한다. 그리고 단서 회상 테스트가 주어질 경우 더욱 그 효과가 뛰어났다. 그러므로 실제 교실 수업에서도 학습 후 테스트나 퀴즈의 형태를 통해 학습자의 학습을 도울 수 있으며, 형성평가 등을 적극 활용한 교수․학습을 설계할 것을 제안한다.

This paper dealt with a pincers-type gripper being able to grip a heavy-weighted cylindrical object having various size with itself. This gripper should be designed to seize the objects without any change of jaw shape. Grasping achieved equilibrium after the object slipped on the jaw while grasping it. To cope with this situation, we suggested the slip considered gripper design procedure based on grasping equilibrium. The obtained slip condition can provide a limit friction coefficient depending on the contact angle when initiating contact between jaw and object. Consequently, the gripping force and the required actuating force can be calculated. In order to verify the proposed slip condition, the simulations were performed using a dynamic software.

최근 유산균을 이용한 다양한 발효 식품들이 연구, 개발되고 있으며, 유산균 발효 식품은 건강 증진 측면에서 효용성을 인정받아 전세계 인구가 섭취하고 있다. 이러한 유산균 발효 식품에 있어서 성공적인 제품 생산을 위해 박테리오파지의 중요도가 지속적으로 증대되고 있다. 특히, 발효 식품들 중 유제품에 대한 박테리오파지의 여러 가지 제어 연구가 다수 수행되었으며, 물리적, 화학적 위생처리를하거나 각각의 방법을 혼합하여 유제품 발효를 보다 성공적으로 수행하도록 하여 왔다. 또한, 최근에는 국내에서도GMP(Good Manufacturing Practice), CIP, SSOP(SanitationStandard Operating Procedures) 등을 유제품 생산 공장에적용하여 보다 효과적인 유제품 생산을 도모하고 있다.