• 한국산업보건학회지
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• 제20권1호
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• pp.47-52
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• 2010

Green tobacco sickness (GTS) is known as an occupational disease among tobacco harvesters, and a form of acute nicotine intoxication by the absorption of nicotine through the skin from the wet green tobacco plant. On the assumption that GTS may occur by inhalation as well as absorption of nicotine, we measured the airborne nicotine concentration in tobacco field and the processing room of tobacco leaves. We measured the airborne nicotine concentrations in the tobacco field and processing room between 13 and 30 July 2008. All sampling and analyses of airborne nicotine were conducted according to the manual of analytic methods of NIOSH 2551, and we sampled 2 times at 11 points in the tobacco field by area sampling. The sampling in the processing room of tobacco leaves was conducted at 3 points, and earlymorning dew was collected from the tobacco by wringing the moisture into specimen bottles. The airborne nicotine concentration [geometric mean (geometric standard deviation)] in the tobacco field in the P.M. was higher [49.2 mg/$m^3$ (1.3)] than the A.M. concentration [43.4 mg/$m^3$ (1.4)]. Similarly, the nicotine concentration in the processing room of tobacco leaves was 224.4 mg/$m^3$ (1.2), and the concentration of nicotine in the dew was 64.7 mg/${\ell}$ (1.7). Based on our results, the airborne nicotine concentration in the tobacco field and the processing room of tobacco leaves were 100 and 400 times higher than the occupational recommended values (TLV-TWA of 0.5 mg/$m^3$), respectively. In the future, it is hoped that epidemiologic studies and environmental measurements will be conducted for GTS which occurs by inhalation of nicotine. If GTS is confirmed to occur by inhalation of nicotine, respiratory and dermal protective equipment must be distributed.

• 한국학교수학회논문집
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• 제17권4호
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• pp.507-539
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• 2014

문자 기호 사용으로 대표되는 대수는 수학 전반에 그 영향력을 행사하는 중요한 도구로 자리매김하게 되었다. 이러한 대수를 적절히 활용하기 위해서는 무엇보다 주어진 문제 상황을 적합한 대수적 표상으로 전환하는 작업이 요구된다. 그러나 문장제에 관한 몇 가지 연구로부터 이러한 전환의 어려움이 보고되고 있다. 본 연구에서는 학생들이 주어진 문장 표상과 기하 표상 각각을 대수적 표상으로 전환 및 정교화하는 과정을 살펴보는데 초점을 두었다. 중학교 1학년 학생 29명을 대상으로 하여 문장으로 기술된 상황과 도형 표현이 추가된 상황을 제시하고 각 상황에서 요구하는 바를 대수적 표상으로 전환하는 능력을 조사한 결과 도형 표현을 대수적 표상으로 전환하는 하나의 문항을 제외하고 나머지 3개의 문항에서 10% 내외의 학생이 부적절한 응답을 하였다. 나아가 그 중 임의 추출한 네 명을 개별 면담함으로써 사고 특징 및 대수적 표상 정교화를 돕는 요인을 조사하였다. 그 결과, 대수 표상 정교화 과정은 급진적이 아닌 점진적 개선 과정임을 확인할 수 있었다. 그리고 대수적 표상 정교화를 요하는 문제에 대해 문제 요구 사항에 대한 오해가 있을 수 있음을 확인할 수 있었다. 또한 자신의 대수적 표상에 대한 설명과 구체적 수치 상황 제시가 정교화에 도움이 되는 요인으로 작용하는 것을 목격하였으며, 아울러 정교화의 경험은 전이력을 가질 수 있음을 확인할 수 있었다. 한편, 변수에 관한 오개념 등식 설정에 고착된 사고는 표상 전환의 방해 요소로 작용할 수 있음을 알 수 있었다. 이러한 결과로부터 대수적 표상 전환 및 정교화를 돕기 위한 몇 가지 교육적 시사점을 도출하였다.

• 한국농공학회지
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• 제40권5호
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• pp.91-99
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• 1998

The widespread use of thin shell structures has created a need for a systematic method of analysis which can adequately account for arbitrary geometric form and boundary conditions as well as arbitrary general type of loading. Therefore, the stress and analysis of thin shell has been one of the more challenging areas of structural mechanics. A wide variety of numerical methods have been applied to the governing differential equations for spherical and cylindrical structures with a few results applicable to practice. The analysis of axisymmetric spherical shell is almost an every day occurrence in many industrial applications. A reliable and accurate finite element analysis procedure for such structures was needed. Dynamic loading of structures often causes excursions of stresses well into the inelastic range and the influence of geometry changes on the response is also significant in many cases. Therefore both material and geometric nonlinear effects should be considered. In general, the shell structures designed according to quasi-static analysis may fail under conditions of dynamic loading. For a more realistic prediction on the load carrying capacity of these shell, in addition to the dynamic effect, consideration should also include other factors such as nonlinearities in both material and geometry since these factors, in different manner, may also affect the magnitude of this capacity. The objective of this paper is to demonstrate the dynamic characteristics of spherical shell. For these purposes, the spherical shell subjected to uniformly distributed step load was analyzed for its large displacements elasto-viscoplastic static and dynamic response. Geometrically nonlinear behaviour is taken into account using a Total Lagrangian formulation and the material behaviour is assumed to elasto-viscoplastic model highly corresponding to the real behaviour of the material. The results for the dynamic characteristics of spherical shell in the cases under various conditions of base-radius/central height(a/H) and thickness/shell radius(t/R) were summarized as follows : The dynamic characteristics with a/H. 1) AS the a/H increases, the amplitude of displacement in creased. 2) The values of displacement dynamic magnification factor (DMF) were ranges from 2.9 to 6.3 in the crown of shell and the values of factor in the mid-point of shell were ranged from 1.8 to 2.6. 3) As the a/H increases, the values of DMF in the crown of shell is decreased rapidly but the values of DMF in mid-point shell is increased gradually. 4) The values of DMF of hoop-stresses were range from 3.6 to 6.8 in the crown of shell and the values of factor in the mid-point of shell were ranged from 2.3 to 2.6, and the values of DMF of stress were larger than that of displacement. The dynamic characteristics with t/R. 5) With the thickness of shell decreases, the amplitude of the displacement and the period increased. 6) The values of DMF of the displacement were ranged from 2.8 to 3.6 in the crown of shell and the values of factor in the mid-point of shell were ranged from 2.1 to 2.2.

• 비교문화연구
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• 제39권
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• pp.219-240
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• 2015

The following summarized argument is the comparative research of the characteristics of automatic techniques demonstrated in the mixed expression of foreign language and Korean language in Lee Sang's poetry. Our research examines the use of foreign languages such as French and English shown in Lee Sang's poems, and then, recognized the characteristics of the automatic techniques demonstrated by the parallel marks and signs of Korean language. The automatical technique's element that Lee Sang made use of is a language of loanblend, consisting of free use of French, English, Japanese and Korean. The mathematical and geometric figures such as numbers and shapes can be seen as an important poetic language. In Lee Sang's poetry, the French words "AMOUREUSES" and "ESQUISSE" and English words "I WED A TOY BRIDE" are considered as parts of Korean language. The use of foreign language is seen by the readers as encodes of a unacquainted language and it provides rhetorical characteritstics that gives off profanatory feeling about the poetry. The poet is seen to have created a new poetic language that excess the standards of the limitations that Korean and Chinese marks have through the application of polysems and poliphonyic effects that foreign languages have. The mathematical and geometric signs are Lee Sang's special experimental elements that can't be seen in other literary poetries. They are conversational and the requirements for the expression of abstract artistry and esthetics. The language used in his poetry are external to those traditional poetic languages and they mix freely with other poetic elements to become an automatic technique used in the writing. Lee Sang's techniques can be considered as the pursuit of defiance and departure, freedom about literature and artistry. Moreover, the avant-garde expressionism is the literary form that demonstrated the sense of inferiority, nervousness and loneliness risen from physical pain and the abnormal relationship with women in the poet's personal life. The technique shows the longingness of the the Western culture and literature that lay dormant in the poet's consciousness and it is also the expression of ingenious that created the new guide in the Korean poetic literature, exceeding the European surrealism. Lastly, the automatic technique images that are demonstrated by the mixture of the foreign languages and Korean language are the creations of an innate poetic language and poetic literature that can't be imitated by anyone in Korean literature.

• International Journal of Control, Automation, and Systems
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• 제4권2호
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• pp.204-216
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• 2006

Latest advances in hardware technology and state of the art of mobile robot and artificial intelligence research can be employed to develop autonomous and distributed monitoring systems. And mobile service robot requires the perception of its present position to coexist with humans and support humans effectively in populated environments. To realize these abilities, robot needs to keep track of relevant changes in the environment. This paper proposes a localization of mobile robot using the images by distributed intelligent networked devices (DINDs) in intelligent space (ISpace) is used in order to achieve these goals. This scheme combines data from the observed position using dead-reckoning sensors and the estimated position using images of moving object, such as those of a walking human, used to determine the moving location of a mobile robot. The moving object is assumed to be a point-object and projected onto an image plane to form a geometrical constraint equation that provides position data of the object based on the kinematics of the intelligent space. Using the a priori known path of a moving object and a perspective camera model, the geometric constraint equations that represent the relation between image frame coordinates of a moving object and the estimated position of the robot are derived. The proposed method utilizes the error between the observed and estimated image coordinates to localize the mobile robot, and the Kalman filtering scheme is used to estimate the location of moving robot. The proposed approach is applied for a mobile robot in ISpace to show the reduction of uncertainty in the determining of the location of the mobile robot. Its performance is verified by computer simulation and experiment.

• 한국인터넷방송통신학회논문지
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• 제13권1호
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• pp.171-180
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• 2013

데이터의 보안은 항상 중요한 문제이다. 특히 현재 각광받고 있는 클라우드 컴퓨팅 시스템은 필연적으로 데이터 보안의 문제가 제기되고 있다. 그러나 단순한 보안방법으로는 더 이상 데이터가 안전하지 않으며, 데이터 보안을 위해서 보다 진보된 방법을 요구하고 있다. 본 논문에서는 기존의 텍스트 기반의 암호 방식보다 더 높은 레벨의 보안방식을 제시하기 위해 이미지 정보 기반의 데이터 내용 접근 제어 방식에 관하여 연구하였다. 원본 이미지에서 히스토그램 값을 이용하여 칼라키를 생성하고 이미지를 변환시켜 위치정보와 색상정보를 추출하여 보안 키를 생성하여 보안처리된 데이터 내용을 접근한다. 끝으로 본 몬문은 제안한 기법를 평가하기 위해 데이터 내용의 접근을 제어할 수 있는 인터페이스를 설계하고 구현하였다.

• 복식
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• 제67권3호
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• pp.133-148
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• 2017

The purpose of this paper is to develop waist coat designs that can be worn in the present day by researching design techniques and traditional waist coat forms shown on Korean patchworks called 'Jokakbo', which was commonly used in our traditional culture. By selecting patchwork as the primary motive in particular. The Bojaki, also known as deungguhli or baeguhli(背巨里), gives off a natural and vibrant color sensation. A new design that could be practically worn with modern clothing was developed by sufficiently reflecting this color sensation as well as the aesthetic quality of its geometric shape. On the basis of theoretical consideration of traditional cloth and vest, total of 7 points were designed and produced. These works contain diverse application of the traditional Bojaki and vest. The design of the Bojaki grants rhythmic sense to the side where diverse colors and formative patterns shown on the cloth can be seen as monotonous. The entire side opening of the traditional waistcoat can cover multiple sizes. Depending on the movement, the front and back naturally spreads. The vest can also be worn in layers or used as a cotton quilt depending on the season. And after minimal design alterations, it will be possible to wear the vest with diverse modern clothing due to its straight line and form.

• 대한조선학회논문집
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• 제54권3호
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• pp.267-273
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• 2017

Pressure hulls of submerged structures are generally designed as circular cylinders, spheres or cones with form of axisymmetric shell of revolution to withstand the high external pressure of deep ocean. The compressive buckling (implosion) due to hydrostatic pressure is the main concern of structural design of pressure hull and many design codes are provided for it. It is well-known that the buckling behavior of thin shell of revolution is very sensitive to the initial geometric imperfections introduced during the construction process of cutting and welding. Hence, the theoretical solutions for thin shells with perfect geometry often provide much higher buckling pressures than the measured data in tests or real structures and more precise structural analysis techniques are prerequisite for the safe design of pressure hulls. So this paper dealt with various buckling pressure estimation techniques for unstiffened circular cylinder under hydrostatic pressure conditions. The empirical design equations, eigenvalue analysis technique for critical pressure and collapse behaviors of thin cylindrical shells by the incremental nonlinear FE analysis were applied. Finally all the obtained results were compared with those of the pressure chamber test for the aluminium models. The pros and cons of each techniques were discussed and the most rational approach for the implosion of circular cylinder was recommended.

• 산업경영시스템학회지
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• 제39권4호
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• pp.1-6
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• 2016

As manufacturing industries become globalized, product design affects every area of organization. The design sets the goals for a number of different departments, so if it fails to effectively communicate these goals, the entire organization is less efficient. In addition, To communicate clearly, the design must represent a product that meets its technical specification. GD&T (Geometric Dimensioning and Tolerancing) is one of the most important factors, which has an effect on efficiency of manufacture system, in designing products. However, most of designers in different industries are prone to ignore the importance of GD&T. To analyse the importance of GD&T compliance with international standards for design drawing, a comparison analysis of the difference between two methods, composite profile control and multiple single segment profile control, is performed on three different cases and suggests how it used to be more suitable. Composite profile tolerance is specified by a dual feature control frame that has one profile symbol specified with two lines of tolerance information. Whereas a multiple single segment profile control is when two or more single segment profile callouts are used to define the location and/or orientation and/or size and/or form of a part feature. In this study, the following results will be provided : a clear definition and an obvious difference of the tolerance zone, datums and datums sequence and minimization of tolerances. On this study, composite profile tolerance and multiple single segment profile tolerance were discussed. Next steps of research will consist on reaching more accurate results for profile control. Further research will be focused on dealing with the remaining 14 symbols of GD&T.

• Tribology and Lubricants
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• 제32권2호
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• pp.56-60
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• 2016

Sapphire has a high hardness and strength and chemical stability as a superior material. It is used mainly as a material for a semiconductor as well as LED. Recently, the cover glass industry used by a sapphire is getting a lot of attention. The sapphire substrate is manufactured through ingot sawing, lapping, diamond mechanical polishing (DMP) and chemical mechanical polishing (CMP) process. DMP is an important process to ensure the surface quality of several nm for CMP process as well as to determine the final form accuracy of the substrate. In DMP process, the material removal is achieved by using the mechanical energy of the relative motion to each other in the state that the diamond slurry is disposed between the sapphire substrate and the polishing platen. The polishing platen is one of the most important factors that determine the material removal characteristics in DMP. Especially, it is known that the geometric characteristics of the polishing platen affects the material removal amount and its distribution. This paper investigated the material removal characteristics and the effects of the polishing platen groove in sapphire DMP. The experiments were preliminarily carried out to evaluate the sapphire material removal characteristics according to process parameters such as pressure, relative velocity and so on. In the experiment, the monitoring apparatus was applied to analyze process phenomena in accordance with the processing conditions. From the experimental results, the correlation was analyzed among process parameters, polishing phenomena and the material removal characteristics. The material removal equation based on phenomenological factors could be derived. And the experiment was followed to investigate the effects of platen groove on material removal characteristics.